LNW80 Microcomputer Operations Manual

By CiarŠn McManus First Edition - October, 1982 All rights reserved. Reproduction or use, without express permission is prohibited. While every effort was taken in the preparation of this book, the publisher assumes no liability for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein. Copyright © 1982, LNW RESEARCH CORP. TABLE OF CONTENTS SECTION 0: INTRODUCTION TO THE LNW80 OWNERS' MANUAL ...... 5 * Documentation * What is a Computer? * I/0 Devices * CPU * Memory * Computer Languages * What is an Operating System? * Utility Programs * Application Programs SECTION 1: UNPACKING THE HARDWARE ....................... 13 SECTION 2: DESCRIPTION OF THE LNW80 ..................... 14 * General Description * Keyboard * Changing Key Definition * Z80A Microprocessor * ROM * RAM * Parallel Printer Interface * Cassette Interface * RS232C Interface * Floppy Disk Controller * I/0 Panel SECTION 3: VIDEO DISPLAY ................................ 22 * Introduction * Monitors for the LNW80 * Connecting a Monitor * Connecting an RGB Monitor * Using the Monitor With BASIC SECTION 4: CASSETTE INTERFACE ........................... 27 * Hooking up a Cassette Recorder * Using a Cassette Recorder * Transfer Speed * Saving a BASIC Program * Loading a BASIC Program * So, it Wonít Load * Verifying a Load * Loading a Machine-language Program * Lower-case with Cassette Based System * Complete Lower-case Program SECTION 5: DISK INTERFACE ............................... 33 * Introduction * What Kind of Disk Drives You Should Use * Configuring 5-1/4" 6 8" Drives * Connecting a 5-1/4" Drive * Connecting 8" Drives * Disk Drive Set-up 6 the 5/8 Switch * Other Considerations * Disk Descriptions * Disk Care SECTION 6: POWER ON ..................................... 41 * Connecting AC Power * Power-up 6 Reset for Non-Disk Owners * Power-up a Reset for Disk Owners * Disk Power-up Malfunctions * Monochrome Monitor Adjustments * NTSC Monitor Adjustment * Monochrome Operation * Color Operation * RGB Monitor Adjustment a Operation * Power Off * Memory Test * High Speed / Low Speed Test * Graphics Test SECTION 7: LNW80 GRAPHICS ............................... 47 * Introduction * Graphics Modes * Mode 0 * Mode 1 * Mode 2 * Mode 3 * Machine-language Overview * Mode 0 Addressing * Mode 1 Addressing * Mode 2 Addressing * Mode 3 Addressing SECTION 8: LINE PRINTER INTERFACE ....................... 70 * Line Printer Types * Outputting to the Printer Using BASIC * Page Length * Line Count * Printer Availability * Adjusting Printer Controls SECTION 9: RS232C INTERFACING ........................... 74 * History of Serial Data Communication * RS232C Standard * RS232C Operation * Connecting Equipment to the RS232C * The Baud * Transmission Techniques * Transmitting and Receiving * Setting Transmit and Receive Rates * Setting Parity * Setting Word Length * Setting Stop Bits * Getting the Most From RS232C * Modem SECTION 10: MEMORY UTILIZATION .......................... 90 * A Look at Memory in a Non-disk System * A Look at Memory in a Disk System * High Memory Protection SECTION ll: CHOOSING AND USING A DISK OPERATING SYSTEM .. 92 * Introduction * Important Aspects of o DOS * Brief History of TRS80 Model I Operating Systems * Looking at the Various DOSes * Top Five DOSes * TRSDOS 2.3 * DOSPLUS 3.4 * NEWDOS80 2.0 * LDOS 5.0/5.1 * MULTIDOS SECTION 12: COMPATIBILITY FEATURES OF THE LNW80 ......... 106 * DOSPLUS 3.4 CONVERT Command * LNWBASIC 6 TRS EXTENDED COLOR BASIC SECTION 13: LNW80 DETAILED DESCRIPTION & SPECIFICATIONS . 111 * General * CPU * Memory * Keyboard * MICROSOFT BASIC Interpreter * Other Features * Video Display Specifications * Floppy Disk Interface * Printer Interface * Cassette Interface * RS232C Interface * Terminal Emulation Capability * Expansion Port * Real-time Clock * LNWBASIC SECTION 14: SHOOTING TROUBLE ............................ 120 * Symptoms, Causes, Cures * Outside Interference APPENDIX A: A BUYERíS GUIDE TO MONITORS ................. 122 * Introduction * Monochrome Monitors * Recommended List of Monochrome Monitors * NSTC Video Color Monitors * RGB Color Monitors APPENDIX B: DISK DRIVE TUTORIAL ......,....,............. 125 * The History of the TRS-80 Disk * Termination Resistors * Drive Selection & Pulled Pin Cables * Double-sided Disk Drives * Double-density Catches On * Configuring 5-1/4" Disk Drives * Eight-inch Drives * Configuring 8" Disk Drives APPENDIX C: MODE 1 DRAWING PROGRAM ...................... 139 APPENDIX D: VIDEO DISPLAY DIAGRAM ....................... 142 APPENDIX E: GLOSSARY .................................... 145 INDEX: .................................................. 157 USER'S RESPONSE SHEET ................................... 167 SECTION 0: INTRODUCTION TO THE LNW80 OWNER MANUAL Congratulations! You have purchased one of the finest personal and small business computers available - the LNW80. The LNW80 is software and hardware compatible with the TRS80 Model I computer. This means that one of the largest and most mature libraries of software will run on the LNW80 without modification. It also means that a huge selection of hardware accessories, such as disk drives, printers, printers, modems, video monitors, data acquisition equipment and much more will plug right in and run. But the LNW80 is more than just a TRS80 work-alike. The LNW features high resolution graphics, color, the interfaces for RS232, 5" and 8" single and double-density floppy disk drives, printer and cassette. The LNW80 comes complete with 12K ROM, 48K RAM and a 74-key keyboard with numeric entry pad. The LNW80 also comes complete with the DOSPLUS 3.4 Disk Operating System (TRSDOS compatible), Advanced Disk Basic (LNWBASIC) and complete documentation. It is housed in a sleek steel case with a cooling fan for increased reliability. This owner manual was written to make your first experience with the LNW80 a pleasant one. It also provides the link between your computer and the following other documentation: 1. Level 2 BASIC Manual Level 2 BASIC is the microsoft BASIC-88 interpreter written for the LNW80. It is the BASIC which is compatible with the TRS-80 Model I LEVEL 2 computer. This BASIC is "BUILT IN" to the LNW80 and is permanently stored an ROM. 2. DOSPLUS 3.4 Disk Operating System Manual DOSPLUS 3.4 is a DOS (Disk Operating System) which is compatible with TRSDOS (Model I). It is authored by Microsystem Software Inc. 3. LNWBASIC Advanced Disk BASIC Manual LNWBASIC (written by Nodular Software Associates) is an extension to the Disk BASIC Interpreter supplied in DOSPLUS 3.4, or to NEWDOS80 version 2.0, LDOS 5.1 and TRSDOS 2.3. This is the part that has graphics, color, programmable key functions and some other advanced features. 4. LNW80 Technical Reference Manual This ls the Service manual for the LNW80. This manual is intended for those technically- inclined individuals. Theory of operations, logic diagrams, trouble-shooting tips, test programs, parts lists, disaasembly and re-assembly instructions are provided. If you are a first-time computer owner -- sit back, relax and read the following section before proceeding to tear the wrapping off your LNW80 computer. If you have owned a TRS-80 or another personal computer (or if you just cannot wait to get your hands on your LNW80) proceed to section 1, entitled "Unpacking the Hardware". What is a Computer? Twenty years ago, the word "COMPUTER" meant an air-conditioned room full of electronics costing millions of dollars. Today the word "computer" can mean anything from a 10 million dollar mainframe computer to the "chip" inside the electronics of your microwave oven. A computer is a machine which can automatically do arithmetic and make logical decisions. Input Output (I/0) Devices The computer can also make data available to and from us via input and output, devices. A KEYBOARD (typewriter style keys) is an INPUT device because it allows us to type information into the computer. This information can then be used by the computer to tell it what you want it to do, or it could be data for calculations or even a typed letter. An OUTPUT device is one that allows the computer to make information available to us. A video display is an output device because it allows the computer to "write" to us via the display screen. This display is fast and can be written over and over again, It has a disadvantage that there is no permanent "record" of this information. Once it "ROLLS" off the screen (SCROLLS), it is lost. A printer is also an output device. It "writes" on paper the information that the computer would like to communicate to us in a more permanent manner. Central Processing Unit (CPU) To make a computer useful, we must have input devices, output devices, and we must perform computations (arithmetic and logical decisions). The device which performs the computation is called the "CENTRAL PROCESSING UNIT" or CPU. The CPU in the LNW80 is the Z80A MICROPROCESSOR. It is the world's most popular 8-bit microprocessor (small processor) and can do thousands of computations in one second. In order for the CPU to do computations, the CPU must be told what it should do in a step-by-step fashion. Each step is an addition, subtraction, logical operation, or input/output operation. These step-by-step operations are called "instructions," or to be more exact, MACHINE LEVEL INSTRUCTIONS. Memory These instructions are stored in main computer storage before being executed. The main computer storage is called MEMORY. Memory as analogous to 65536 mailboxes in a row on a very long street. Each mailbox has an address marked on it from 0 to 65535. Each mailbox may look different on the outside, but can only hold the same amount of materia1 inside. Each location of a mailbox as called a "memory location," or "memory ADDRESS". For an 8-bit CPU, each address can contain a number from 0 to 255. This corresponds to 2 to the eighth power or 2exp(8) or 2x2x2x2x2x2x2x2=256. The reason that there are 65536 memory locations as due to the memory addressing capability of the Z80 microprocessor. Most of the eight-bit microprocessors have this home addressing capability. Smaller CPU's (4-bit) address fewer locations, and larger CPU's (minicomputers and some 16-bit. CPUís) can address much larger memories (sometimes millions of locations). The advantage of larger memories is the ability to have much larger programs. Since memory is not cheap, this does cost money. There are techniques of storing large programs in modules so that only a few modules need to be in main computer storage at any time, thus allowing larger programs to run in a smaller address space. This as called memory management, or as it is more commonly referred to an the microcomputer world - OVERLAYS. OVERLAYS are just come of the programming techniques made easy by LNWBASIC, and DISK BASIC. In the LNW80, memory takes two different forms. There is ROM (Read Only Memory) which as a "hard wired" memory that cannot be changed, and there is RAM (Random Access Memory - also called Read/Write Memory), which can be changed, but will disappear when power is removed from the computer. Instructions, when executed as a group to perform a desired function are called PROGRAMS. Computer Languages Just as people developed a variety of languages to communicate with each other, so there would become a variety of languages to communicate with computers. COMPUTER LANGUAGES are machine level programs that make communication between us and computer easier. Hundreds of computer languages have been developed, and with time, even dialects of languages developed. Cobol, Snobol, Algol, Fortran 4, Fortran 77, BASIC, Tiny BASIC, Extended BASIC, Level 2 BASIC, Disk BASIC and Advanced Disk BASIC are dialects of some fundamental computer languages. These languages are called HIGH-LEVEL LANGUAGES. By high-level we mean that a single high-level language instruction is translated into multiple machine-level instructions. This reduces the amount of time required to tell the computer what to do - which simplifies programming. This translation can occur during the time that the program is being run (RUN-TIME), or the translation can be done in advance, with the final translated version of the program (COMPILED OBJECT CODE) stored for later execution. A run-time translator is known as an INTERPRETER. One of the advantages of an interpreted high-level language is the reduced memory requirement for storing and executing the program. Since the high-level language is in memory during the execution, the program also can take advantage of the error recovery facilities of the high-level language. This makes interpretive languages qenerally easier to program and easier to get the "bugs" out of the program (DEBUG) to make it operational. All the levels of BASIC supplied with the LNW80 are interpretive. A translator that does the translating in advance of execution is commonly referred to as a COMPILER. A compiler has the advantage of execution speed since it has all the instructions, translated in advance and can directly execute the translated instructions. Assembly-Language Assembly-language was the first of the computer languages developed. It allows symbolic notation to represent machine-language instructions. This makes for an easier way of programming machine level instructions. This is sometimes confusing to first-time computer owners, since much literature is written using the terms MACHINE-LANGUAGE and ASSEMBLY- LANGUAGE interchangably. The program that compiles the assembly-language program is called an ASSEMBLER. For more details concerning assembly-level programming, we recommend the following book, available from Radio Shack: TRS80 Assembly-Language Programming by William Barden Jr. BASIC The most popular language used on the LNW80 computer is BASIC. BASIC (Beginner's All-purpose Symbolic Instruction Code) was developed at Dartmouth College in 1965. It has since become the most widely used language of microcomputers and small business computer systems. Both interpretive and compiled forms of BASIC are commonly used. The LNW80 is supplied with four levels of interpretive BASIC: 1. Level II BASIC (FOOTNOTE - if you are wondering what happened to level 1, it is a small, very limited BASIC that was originally sold on the TRS80 Model I and Model III) occupies 12K (12 X 1024) bytes of memory, and is permanently stored in ROM. It has full line editing features, string variables, multiple dimension arrays, 14-digit accuracy, low resolution graphics, cassette I/0, Video I/0, Printer I/0, scientific functions, string-handling operations, etc. 2. DOSPLUS 3.4 TINY DISK BASIC - This is supplied on the DOSPLUS 3.4 diskette and provides an extension to the above BASIC. It adds floppy disk file handling, advanced keyboard I/0, in-string search command, programmer-defined BASIC instructions, and loading, saving, killing, merging BASIC programs to and from the floppy disk drive. 3. DOSPLUS 3.4 EXTENDED DISK BASIC - This BASIC adds to the above BASIC the following features: 1. Execute DOS commands from BASIC 2. Advanced editing features 3. Program line renumbering 4. BASIC array sort verb 5. Controlled screen input routine 4. LNWBASIC Advanced Disk BASIC - This adds even more commands to the above BASIC and is supplied on a 35-track single-density data disk. It can be used with either Extended Disk BASIC or Tiny Disk BASIC. It adds up to 40 new commands to BASIC. It has a "creator" mode which allows the programmer to create the BASIC he wants by selecting from a menu of new commands which include: 1. High resolution graphics and color commands 2. Programmable keyboard features 3. Programming shorthand notation 4. Machine Language "CALL" command 5. Sound command 6. RS232 communications from BASIC 7. Printer Spooler 8. Execute string as BASIC statement 9. Block and blinking cursor 10. Do/Until Construct and Much more... BASIC Compilers There is quite a variety of BASIC Compilers available for the LNW80 computer. The biggest disadvantage of most of these compilers is the lack of compatibilty with their interpretive counterparts. The Compiler BASIC available from Radio Shack is not compatible at all. The Microsoft BASIC Compiler (for the R/S Model I) is almost completely compatible with the DOSPLUS 3.4 Tiny Disk BASIC (including disk I/0), but it does have its limitations and cannot take advantage of some of the advanced features of DOSPLUS 3.4 Advanced Disk BASIC or LNWBASIC. There are other compilers that vary in price and features end can be found advertised in the computer magazines or available from your local computer dealer. Other Languages One of the reasons for the many computer languages is that the high-level language programmers have different needs as to the high-level instructions they would prefer to use. For example, scientific applications require fast data computation, scientific accuracy, easy formula evaluation and special scientific functions (trigonometry functions, etc.) FORTRAN (FORmula TRANslation) provides this by having instructions which can do these types of functions easily. Fortran is not a good language for business since it does not have some of the high-level instructions for manipulating business data. Cobol (COmmon Business Oriented Language) was developed for this purpose. Both Fortran and Cobol are compiler languages. FORTRAN, COBOL and ASSEMBLER are available for the LNW80 from a variety of sources including RADIO SHACK. Some of the other languages that run on the LNW80 are PASCAL, FORTH, "C" and many others, What is an Operating System? The Level II BASIC ROM in the LNW80 computer has a CASSETTE OPERATING SYSTEM built in. This means that it provides a method for loading, storing, and executing BASIC programs to and from cassette and the loading and executing of machine level programs from cassette. It also provides the overhead functions, such as communicating with the keyboard and the video display. In addition, it provides a method of loading in from disk, the DISK OPERATING SYSTEM (DOS). This loading of the DOS from the disk drive is called the BOOTSTRAP LOADER. This is commonly referred to as "booting the disk." When the disk is "booted," the first 256 memory locations on the disk drive are loaded into main memory and executed. These first 256 locations are called the BOOT SECTOR. This 256-byte program then loads the rest of the operating system from the disk into main memory where it can be executed. The disk operating system supplied with the LNW80 is DOSPLUS 3.4. This is a very powerful, yet easy-to-use system that provides the following functions: 1. Keeps track of programs and data (sometimes referred to as FILES) stored on the disk. A DIRECTORY of programs and data is kept. DOSPLUS allocates space on the disk for programs and data, and the DIR command allows the operator to view the contents of the disk at any time. 2. Provides a set of functions that the operator can use to manipulate the programs and data on the disk and other useful tasks. This set of commands is called the LIBRARY of disk commands. The LIB command will display all available functions. Here are a few examples of these functions: COPY - Allows the transfer of a program or data from one diskette to another. AUTO - Automatically execute an application program when the disk is "booted." DIR - Display the contents of a selected disk. CLOCK - Display the time of day on the screen. RENAME - Change the name of a file. KILL - Delete a file from the disk. BUILD - Create a file that is a series of DOS commands or programs to be linked together to run automatically. 3. Provides some specialized utility programs such as: BACKUP - Duplicate the entire contents of one disk onto another disk. FORMAT - Initialize a blank diskette in such a way that it has a directory of disk space and contains fields designed for storing information. DEBUG - Display and manipulate the contents of memory and display the contents of the internal Z80A CPU registers. Debug also provides the abilty to set stopping points to assist in getting a machine level program to work. DISKZAP - Display, modify or verify the contents of the diskette itself. SPOOL - Store what would nomally print on the printer in main memory and print as a background function (the printer is usually very slow) while the operator is running another program. DO - Execute a BUILD file. A build file is a series of DOS commands or programs which can be linked together (using the BUILD command) to operate automatically. In the larger computers this program control language is called a Job Control Language (JCL) and is used to link programs together to increase the efficiency of running a computer. 4. Provides the following BASIC interpreters: TBASIC - The TRSDOS 2.3 compatible BASIC BASIC - The Extended Disk BASIC For more details concerning the above features of DOSPLUS 3.4, refer to the manual entitled: USER MANUAL Ver A.x for DOSPLUS 3.4 DISK OPERATING SYSTEM Utility Programs These are generally (but not necessarily) written in machine-language and provide some useful function for programmers. An example of a utility program available from your dealer is CHARM. This program allows the you to create new character sets for use in BASIC programs. As mentioned earlier, there are many utility programs supplied with DOSPLUS 3.4. Application Programs An application program is a program which is written in machine-language or a high-level language that performs some specialized application. Games, accounting and financial programs, word processing and text editing programs, and specialized industrial or business programs are all examples of application programs. The entire manuscript of this manual was prepared using the ELECTRIC PENCIL program. The ELECTRIC PENCIL is a word processing and text editing program available from your local dealer. SECTION 1: UNPACKING THE HARDWARE Now that the LNW80 Computer is in your possession, let's get it out of the box and have a look at it. Decide where you are going to put the computer before unpacking. Avoid the temptation of setting it up on the floor, where the wayward foot is a very plausible source of destruction! Clear a space on a convenient table or desk that is near a power plug. You should also have a power strip or plug bar for the various pieces of equipment that will need 110V AC power. The LNW80 is packed within a special protective foam cushion. Fold back the packing, lift out your LNW80 Computer and set it on the desk or table top. After you have removed the computer, you will notice that there is a package of printed material on the bottom of the carton. This package contains your warranty information. Read it carefully; fill out the warranty card and then mail it as soon as possible. This packing list contains the equipment list. To ensure that you have everything, check the list now. If you do not have all of the equipment listed, notify your dealer immediately. Now that your LNW80 Computer has been unleashed from its package, letís sit back for a minute and describe the LNW80 in a little more detail. Note: Keep all packing materials. In the event that you have to transport your computer, the packing material will help to ensure safe passage. SECTION 2: A DESCRIPTION OF THE LNW80 COMPUTER The LNW80 computer comes to you with keyboard encased in a steel housing. At first sight the most conspicuous features are the 62-key keyboard and the 12-key numeric pad. Above the numeric pad is the POWER-ON light. The input/output (I/0) panel (for connecting peripheral equipment) is situated at the rear of the housing. The following is a list outlining the main features of the LNW80 Computer: * 74-key keyboard (including a 12-key numeric pad) for inputting data and programs. * Z80A microprocessor with a 4Mhz clock. * 12K Read Only Memory (ROM) containing the Microsoft BASIC Language interpreter. * 48K Random Access Memory (RAM) to store your programs and data. * Real time clock. * Parallel Printer interface. * Cassette interface. * RS232C communications interface. * Single and double-density floppy disk controllers with 5-1/4 and 8 inch drive zero switch. * 24 by 80 character screen capability. * High resolution graphics in color and b/w. * Upper and lower case character sets. * 4MHz or 1.77MHz processor speeds. * Cassette I/0 at either 500 or 1000 baud. * Three video output jacks. * Heavy duty power supply. * All gold-plated edge card connectors. All of these components are housed in a single steel case and are powered by a single power cord. Figure 2.0 - 3/4 Front view of the computer.

Figure 2.1 - 3/4 Rear view. Keyboard The LNW80 keyboard is pictured in Figure 2.2. The keyboard allows you to interact with the computer. You enter data, programs and control characters by typing on the computer keyboard. The main section of the keyboard is similar to that of a typewriter, with some extra keys which relate strictly to computer functions. To the right of the keyboard is a numeric pad to facilitate data entry in accounting or mathematical applications. Figure 2.2 - Photo of LNW80 Keyboard

RESET - There are two reset keys, one on each side of the main part of the key board. The RESET keys are used to reset the computer AFTER it has been initially turned on. If you donít have disks, reset the system by holding down the BREAK key and then pressing both RESET keys simultaneously. If you have disks, reset the system by pressing both RESET keys. ENTER - When you type or enter data into the computer, you must press the ENTER key to signal the computer that you are finished with your input. The computer will then process the data you have entered. BREAK - This key generates an escape code which is used by the BASIC interpreter to stop execution of a program. It is also used in word processing applications and in some system programs, e.g., DISKZAP, which comes with the DOSPLUS disk operating system. BREAK will not usually return control to you when the system 'hangs.' For example, if you try to CLOAD a program from cassette and itís not set up correctly, the system hangs. It will now ignore your incessant pounding on the BREAK key until you either hook-up the cassette recorder correctly or RESET the system. CONTROL - This key is used to generate special codes when used with another key. It is especially useful in data communications and word processing. HIGH/LOW - Ordinarily the LNW80 Computer runs at a clock speed of 4MHz (4 million cycles per second). Certain input/output (I/0) situations may require a slower processing cycle, in which case, this key may be pressed to give a clock speed of 1.77MHz. The 4MHz speed is over twice the speed of the TRS80 Model I. When programs written for the Model I are run on the LNW80, they may run up to twice as fast. Since this may not always be desirable, just press the HIGH/LOW key down to return to TRS80 model I speed. The HIGH/LOW key also serves to select the data transfer rate for the cassette interface. When the H/L key is in the HIGH position, data as SAVERS or LOADed at 1000 baud. With the key down, data transfer is at 500 baud (TRS80 model I compatible). The processing speed of the computer is also affected by the AUTO SWITCH (see Figure 2.3) . With the AUTO SWITCH in the ON position (up) and the HIGH LOW key in the HIGH condition (up), the LNW80 will automatically switch to the 1.77MHz processing speed for ALL disk input/output operations. It will automatically return to HIGH speed when the disk operation is complete. This allows programs written on TRSDOS 2.1 & 2.3 (as well as NEWDOS 2.1 and operating systems listed in Section 11, Table 11.0 which have a NO in the '4MHz OK' column) to operate at the high CPU speed except for disk I/0. If these operating systems are run at 4MHz during disk I/0, a "DISK ERROR" message will be displayed. Note: NEWDOS80 2.0 will run at 1.77MHz all the time if the AUTO SWITCH is ON (up). RIGHT ARROW - Tab key. Tabs 8 spaces to the right. LEFT ARROW - Backspace one position and delete. CLEAR - Clears screen, homes cursor, switches to 64 characters per line. Fl and F2 - The Fl key generates a down arrow. The F2 generates a right arrow. Disk operators use key to effect same; otherwise, Fl generates an elongated colon (|) which can be used to make lines down the page, and the F2 key generates the Yen character These characters may by used for normal input or as special program keys in applications programs since they generate normal ASCII characters. These ASCII codes are: Down arrow 92 Right arrow 94 Elongated colon 124 Yen character 126 Since these keys are not present in the TRS80 Model I, they can be reprogrammed using LNWBASIC while still maintaining the normal functions of all the standard keys. (See DEFKEY in the LNWBASIC Manual). CAPS LOCK - This key provides you with a means of locking all the alphabetic keys into upper case. Fl, F2, "0" and the underscore key (to the left of the down arrow) are also affected. Fl generates a down arrow, F2 generatee a right arrow, "0" generates "0" and the underscore key generates an underscore when the CAPS LOCK is down. The CAPS LOCK is only sensed by programs which use it during the program LOAD. For example, when DOSPLUS is first booted, the switch is sensed. If the CAPS LOCK is down, all alphabetic characters will appear as upper case characters, regardless of the SHIFT key operation. The same applies to application programs such as Visicalc, where it is useful if you only want to make your entries in upper case. The CAPS LOCK is similarly sensed in Electric Pencil, ST80 and many other application programs. Note: Set the CAPS LOCK just prior to loading your program. Changing the setting while the program is running will give rise to unintelligible displays and may cause data loss. The SHIFT Key: As with a typewriter, the SHIFT key is used to print the upper symbol on dual-symbol keys. The SHIFT key is, in fact, used in a number of combinations as listed below in DOSPLUS, BASIC (all kinds), Electric Pencil and most application programs: KEY FUNCTION <SHIFT><right Switches to 32 charaters/line arrow> <SHIFT><left Backspace to beginning of line & erase arrow> <SHIFT><@> Stalls program execution, e.g., a listing. Hit any key to continue <SHIFT> 0 Toggle between: (a) capitals only, or (b) capitals and lower case on the A - Z keys. In mode (b), switch from upper to lower, or vice versa using . Available to disk operators only. Changing key definition Using the LNWBASIC command DEFKEY, you may redefine any 10 keys as strings of ASCII character codes of length 1 or more. You may also use the Quickey option in LNWBASIC to enter entire commands by just pressing one key. See the LNWBASIC manual for more details. Z80A Microprocessor Often called the Central Processing Unit (CPU), this is the focal point of all events taking place within the computer. All the calculations and logical operations are carried out here and then routed or addressed for storage, video display, printing, etc. Sometimes the CPU is referred to as the "brains" of the computer. The microprocessor has two operating speeds. The higher operating speed is 4MHz. A lower operating speed is obtained at the flick of a switch, as explained in the HIGH-LOW notes above. The Z80A belongs to the 8080 family of microprocessors. It has 158 machine-language instructions (including all 78 8080 instructions) and 16 internal registers, It is capable of processing approximately 400,000 instructions per second. ROM ROM stands for Read Only Memory. The ROM memory is preprogrammed. There is 12K of ROM in your LNW80 Computer. The "K" unit refers to 1024 single units of storage. These units are known as "bytes." The ROM contains the MICROSOFT BASIC and other information required by the CPU. As the name implies, information may only be read from ROM. You cannot write or store information in ROM. RAM RAM refers to Random Access Memory. A more accurate name would be Read/Write Memory. As this latter name suggests, RAM can be either written to or read from. It is true that RAM is accessed randomly, but so is ROM. However, unlike ROM, RAM loses the information stored in it when the power to the computer is turned off. The contents of RAM can also be changed at any time, whereas those of ROM cannot be changed. You can address a total of 65K of memory address space in the LNW80 computer. Of this, 48K is available for programming use; 16K x 6 bits is used for graphics, and the remaining 1K is tied up for video use. Parallel Printer Interface The parallel printer interface allows you to attach any Centronics-compatible parallel printer and get a "hard copy" of your programs and other files. It is invaluable if you intend to use your computer for word processing, invoicing or other applications where the printed word is a must. Cassette Interface If you do not intend to use disk drives, the need will arise for you to store your programs for later recall. You will also find that many programs (even programs for disk) are distributed on cassettes. A cassette player can be attached to your LNW80 computer that will allow you to read and write programs and data to cassette tape. The LNW80 allows you to output data to tape at either 1000 or 500 baud (bits per second). The baud rate is controlled by the HIGH/LOW speed switch. In the HIGH position, the tape is recorded at 1000 baud; and in the LOW position, it is recorded at 500 baud. Standard TRS-80 Model I cassette tapes are recorded at 500 baud. RS232C Communications Interface This interface will allow you to communicate via a modem and telephone with any other computer similarly equipped. It also serves as a serial printer interface. The RS232C port may be configured to the various settings required by serial devices by setting switches located on the rear panel (see Figure 2.3) or by software. Expansion Port The expansion interface is located on the I/0 panel at rear. This interface allows you to connect such devices as speech and music synthesizers to your LNW80 computer. For more details see section 13 and the LNW80 Technical Reference manual. Single- & Double-Density Floppy Disk Controller Your LNW80 Computer has a single/double-density disk controller that will support 5-1/4 and 8 inch, dual or single headed, floppy disk drives. 5-1/4 and 8 inch drives may be hooked up in any order on the disk drive cable. When applied to storage on disks, density refers to the amount of information that, can be stored on a storage medium. Specifically, in the case of floppy disks, it refers to the number of bits per track. Double-density offers 80% more capacity and twice the data transfer rate of single-density. Single-density is retained for compatibility reasons. To take advantage of this increased potential for storage, a microcomputer must have, as part of the hardware, a double-density floppy disk controller (as does the LNW80). Also, the disk operating system (DOS) used in a disk drive system must take advantage of this hardware. The big advantage of double-density storage is that it helps to reduce costs by minimizing the number of disk drives required. The Input/Output Panel At the opposite end of the computer from the keyboard is the input/output (I/0) panel. It is to this panel that all of the peripheral devices are connected. And, as a picture is worth a thousand words, see Figure 2.3. Figure 2.3 The I/0 Panel

SECTION 3: VIDEO DISPLAY Introduction You will require a video display unit (VDU or monitor) to operate your LNW80 Computer (The video display is sometimes called a CRT or Cathode Ray Tube). Your selection of VDU will no doubt depend on what you want from your computer. If color graphics is your bag, then a color monitor of some sort is required. An ordinary color TV (NTSC) will suffice, but there are some limitations when using a TV set as a monitor. The resolution of a TV set is not sufficient for the display of text unless the display is set for a screen width of 32 characters. Also, you will need to attach an R/F modulator between your LNW80 and the TV set. TV sets arenít very good monitors, and because of the low resolution, graphics displays are rather fuzzy. An NSTC color monitor, with composite video input, will provide good color graphics and text an 32 characters per line mode. An RGB (Red Green Blue) color monitor will provide excellent resolution for graphics and text. See Appendix A, "A Buyer's Guide to Monitors". Connecting a Monitor Set the monitor on top of the computer and locate the three monitor jacks on the I/0 panel at rear (see Figure 3.1). Notice there are separate jacks for B/W, color TV with RF modulator or color monitor, and RGB monitors. Attach your monitor with the appropriate cable. The B/W and color TV cables are standard computer-to-monitor connector cables. Connecting an RGB Monitor The RGB monitor has a separate gun for each of the three colors red, green and blue. Each gun requires a distinct signal, and hence, the computer-to-monitor cable is a little more sophisticated. You will notice that the RGB jack is a six-pin DIN type female connector. A mating connector for this jack is provided; however, you will have to provide the cable and connector for the RGB monitor. Below are the pin specifications for the monitor and RGB connectors: LNW80 RGB Connector Signal Monitor Connector Pin 1 Vertical Sync Pin 8 Pin 2 Blue Pin 4 Pin 3 Green Pin 3 Pin 4 Red Pin 2 Pin 5 Horizontal Sync Pin 7 Pin 6 Ground Pin 5,6 The RGB interface is shown below with pin numbering. Figure 3.1 - LNW80 RGB Monitor Jack

Figure 3.2 - LNW80 Video Display

Note: For "First Time Through The Manual" People . . . If this is your first time reading through the manual, please move on to the next section at this point. When you have made your way through Section 6, entitled "Power On," the rest of this section will make more sense.

Using the Monitor with BASIC Cursor After performing an operation, BASIC announces its return to the immediate mode as follows: READY >_ ( ">" = PROMPT, "_" = CURSOR ) The cursor may be moved along the line by the space bar or the right arrow, which tabs eight spaces to the right. Scrolling When the cursor is positioned on the bottom line of the display and ,you depress the ENTER key, another line is added to the display. At the same time, all the lines currently displayed move upwards, and the line at the top is erased. Inverse Video Inverse video can be generated by the following program. You may have to brighten the screen to observe the effect. (Results can vary with different monitor types). 10 A=INP (254) 20 A=A OR 1 30 OUT 254,A Inverse video is only good for black and white. It is not defined for color. Text Characters The BASIC program below displays the text characters together with their ASCII codes that are available from the character generator. 10 '......TEXT GENERATOR 15 CLS: X=0 20 FOR K=32 TO 127 30 PRINT @ (X),Z; CHR$(Z) 40 LET X=X+8 50 NEXT Z You may alter the text and graphics characters by using the CHARM program, which is available from your dealer. Graphics Characters The low-resolution graphics characters available from the character generator and their accompanying ASCII codes are displayed by this next program. 10 í.....GRAPHICS GENERATOR 20 CLS: X=0: Y=0 30 FOR Z=128 TO 191 40 PRINT @ (X),Z; CHR$(Z) 50 LET X=X+8: LET Y=Y+1 60 IF Y/8=INT(Y/8) THEN X=X+64 70 NEXT 80 GOTO 80 to exit program. You can display any of the characters yourself by typing: PRINT CHR$(nnn) ... where nnn is a whole number from 128 to 191 inclusive. Character Size 32 Characters per Line: The 32 characters per line mode can be effected from the keyboard by using the combination. Return to 64 c.p.l. by CLEARing the screen. 80 Characters per line: This feature is only available to Disk Operating Systems (DOS) owners. The program to generate this display, called a "driver," is loaded from disk after booting up the system. These drivers are available from your dealer. Before trying to load the drivers, read Section 5 concerning the disk interface. Drivers are available to generate both an 80xl6 and an 80x24 display. These drivers have limitations, however, in that they cannot be used (to date) in word processing applications. 40 Characters per line: Depending on which 80x24 driver is in use (or up), using introduces the 40x24 display mode. Programmable Character Font With the use of CHARM (available from your computer dealer) the LNW80 can have user programmable character sets. The user can program foreign language, scientific and even special graphics symbols, and then save them to disk. CHARM features three display formats: 80 x 24 80 x 16 and 64 x 16. CHARM also features standard video as well as inverse video on a character by character basis. SECTION 4: CASSETTE INTERFACE Hooking up a Cassette Recorder Any good quality cassette tape unit may be attached to the LNW80 Computer with a cassette cable (Figure 4.0). The cassette cable is available from your local Radio Shack store (Radio Shack Catalog No. 26-1207). A cassette player is not required for immediate operation. However, if you have one available and intend to store programs and data on tape, now would be an appropriate time to attach it to the computer. The cable has a DIN plug at one end and three color-coded miniature phone plugs at the other. The DIN plug is attached to the cassette jack on the I/0 panel (Figure 4.0). The DIN plug may be attached to the computer only one way, so there is no danger of plugging it in backwards. Figure 4.0 - Cassette Cable Attachment

The phone plugs are connected to the cassette player by color code as follows: GREY - connects to the AUXillary input SMALL GREY - connects MIC REMote control BLACK - connects to the EAR phone input The AUX line carries information from the computer to the cassette tape. The EAR line carries information in the other direction, from the cassette to the computer. The MIC REM line carries a signal from the computer which controls the motor in the cassette player. Using a Cassette Recorder A cassette player provides a handy, low-cost method of loading and storing programs. If this is your first computer, experiment to get familiar with cassette player operation before storing any close-to-your-heart programs. Before playing with the cassette recorder, it would be a good idea to clean the tape heads and the rubber pinch roller with isopropyl alcohol. An alcohol swab after every few hours of use, will keep the heads and roller clean. So called "cleaning tapes" are not recommended, as their abrasive action may damage the heads. Cheap tapes are not recommended. Transfer Speed Programs and data can be transferred to and from the tape surface at two different transfer speeds. The faster transfer rate is 1000 bits per second (baud), and the slower rate is 500 baud. By using the key, you switch to fast or slow, respectively. The faster transfer rate (1000 baud) allows you to save and load programs twice as fast as the slower rate, and in addition it saves tape. The faster rate is also more sensitive to tape noise while loading. For this reason, the tape should be well erased (see below) before SAVEing programs or data to it. Always note at which speed a program was saved, as programs saved at one speed cannot be loaded at the other speed. SAVEing a BASIC Program Begin with a blank tape. To blank a tape, run a commercial tape eraser slowly over the surface of the cassette a few times. Alternatively, you may put a shorting plug in the AUX input, insert the cassette and place the recorder in record mode. 1) Mount the cassette in the recorder and run it forward a little to clear the non-magnetic strip at the ends of the tape. Note position of tape counter and transfer speed. 2) Put recorder in record mode. 3) Type: CSAVE"N" where N is a one-character name of the program. LOADing a BASIC Program 1) Mount cassette and set recorder in play mode just a little before start of the program on tape. Set the transfer speed and adjust volume control to mid-range. 2) Enter: CLOAD"N" where N is the name of the program. If no program name is specified, the first program or file encountered will be LOADed. When the program begins LOADing, an asterisk will appear in the upper-right corner of the screen. This means that it has found the synchronization pattern that leads the file on tape. So far, so good! Next the file name is read and compared with the requested filename. If the names match, the file will be LOADed. WhiIe the file is being loaded, a second asterisk will appear to the right of the first. If the LOAD is successful, this second asterisk blinks. If the file names do not match, the first asterisk remains on display while the next synchronization pattern is searched for. So It Won't Load If the second asterisk doesn't appear after a short time, or appears and fails to blink, the program is not LOADing correctly. Go through the list below. The solution will most likely lie within the bounds of steps 1 through 3. 1) Check that all electrical connections are secure. 2) Check that the transfer speed is correct. 3) Starting with the lowest volume setting, proceed a half-step at a time for each LOAD attempt. 4) If there is a tone control, adjust it. 5) Demagnetize the head of the recorder. 6) REWIND and FAST FORWARD the tape a few times to remove any tape surface debris. 7) If you have just turned on the computer, let it warm up for a few minutes before attempting another LOAD. 8) Unplug the earphone jack and play the tape to check where the program begins and to make sure you have a program. 9) Try another cassette recorder. Verifying a LOAD or SAVE When a SAVE is complete, the computer responds with READY >_ To ensure that no errors have occurred during the transfer of data, rewind the tape and ENTER CLOAD? "N" This will compare the version of the program loaded into the computer with the program on tape. If all went well, the computer replies with READY >_ In the event of an incorrect read, the response will be BAD SAVE the program again and repeat the procedure. In the case of LOADing, rewind the tape after the LOAD and proceed as above. If the program continues to misbehave during the SAVEing or LOADing procedure, take a break before you drive yourself crazy! On your return, take a look at the cassette recorder. Examine the rubber pinch roller. If it's smooth and shiney, it may not be gripping the tape properly, with tape slip resulting. Clean it with isopropyl alcohol and then rough it up lightly with a strip of emery paper. If the program loads but fails to run, and upon scrutiny reveals erroneous characters here, there and yonder, then you have probably CSAVEd your progran on a tape that wasnít fully blanked. Loading a Machine Language Program As with the BASIC program, mount the cassette in the recorder and rewind to the correct position. Then enter the command SYSTEM The computer responds with *? to which you add the program name *? PROGRAM Press the PLAY button on the recorder. As the program loads, an asterisk will appear on the top right hand corner of the screen, followed by a second blinking asterisk immediately to its right. When the program has loaded, the prompt reappears ... *? You are presented with three options at this point: (i) respond with to return to BASIC (ii) you may load a second program (iii) respond with *? / ENTRY ADDRESS if you want to execute the program at a specific location in memory, or, *? / if the entry address is specified by the program. Lower Case With a Cassette Based LNW80 Computer The LNW80 computer has the hardware necessary to implement lower case characters. Since hardware does not function without software, the following program is included. Note that this program is not necessary when the LNW80 is used with cassette or disk versions of word processors such as ELECTRIC PENCIL since they contain their own display drivers that support lower case. This program is also not necessary when the LNW80 is used with disk drives and one of the following operating systems: 1) DOSPLUS 2) NEWDOS80 3) MULTIDOS 4) LDOS 5) VTOS 6) Any other operating system or program that supports lower case. Complete Lower Case Program This program allows the full implementation of the lower case in BASIC. It has only one known peculiarity, - the "@" key will display as the monetary pound symbol in the unshifted position. Before typing in the program, type in a short program and verify that it can be saved to cassette. Once this is done, begin typing in the program. Check carefully for typing errors. Once you have the program typed in, save the program out to cassette at least twice. Then perform a cassette verify with the CLOAD? command, Make sure that your recorder is correctly set to playback before attempting this. Once the program has been entered and saved to cassette, you may now attempt to use it. This is done by setting the memory size to 65375 on power up and then loading the program off cassette. List the program to verify a good load and then type RUN. The program will then ask the operator if both upper and lower case is desired. Unless you respond with N the program will assume that you want both upper and lower case characters. LOWER CASE PROGRAM 10 REM SET MEMORY SIZE AT 65375 20 FOR X=-160 TO -1:READ I: POKE X,I:NEXTX 30 POKE 16414,96:POKE16415,255:POKE16422,167:POKE16423,255 40 INPUT"WOULD YOU LIKE UPPER AND LOWER CASE (N=NO)";A$ 50 IF A$="N"THENPOKE16409,0ELSEPOKE16409,1 60 DATA 245,58,24,64,254,01,32,6,121,197,205,59,0,193,58,25 70 DATA 64,254,1,40,4,241,195,88,4,241,221,110,3,221,102,4 80 DATA 218,154,4,221,126,5,183,40,1,119,121,254,128,210,166,4 90 DATA 254,32,218,6,5,254,64,218,125,4,254,96,48,5,246,32 100 DATA 195,125,4,230,159,195,125,4,58,25,64,254,1,32,20,121 110 DATA 254,65,56,14,254,122,48,l0,254,91,56,4,254,32,56,2 120 DATA 238,32,79,58,26,64,254,1,194,141,5,l21,254,13,40,5 130 DATA 254,l0,194,141,5,l7,0,32,27,122,179,32,251,62,13,50 140 DATA 232,55,17,00,32,27,122,179,32,251,62,10,50,232,55 150 DATA 17,0,48,27,122,179,32,254,l4,13,201,0,0,0,0,0,0 SECTION 5: DISK INTERFACE Introduction A disk drive system has the great advantage over tape in that it permits greater dexterity in handling masses of information. Large amounts of information can be stored or accessed quickly, reliably and with a minimum of fuss. Programs and files can be loaded from disk about 250 times faster than from tape. Files can be manipulated with relative ease and can be designed to suit a particular application. In a disk operating system (DOS), the operating system for the computer resides on disk. A DOS is more powerful than the ROM operating system. It affords flexibility as regards data storage and makes available problem-solving programs (debugging software) to observe data at almost any memory location within the system. The LNW80 allows you to attach up to four disk drive units to the disk interface. These may be 5 1/4 inch or 8 inch drives, a combination of both, or even hard disk drives. Dual headed drives (two read/write heads) may also be used, but in this case, only 3 drives are allowed. Disks may be formatted in single-or double-density. As an introduction to disk drives and their development, you might want to read through Appendix B before reading this section. What kind of Disk Drives should you use? The LNW80 will work with virtually any type of disk drive (once configured for the LNW) and any floppy disk. Armed with this knowledge, you may be tempted to use the cheapest disk drives you can find. However, these may prove to be quite a frustation, so with your long term mental health in mind, we make the following suggestions: 1). Use double-density rated disk drives. Single-density drives may work, but the proper operation in double-density cannot be guaranteed for the life of the drive (See list of compatible drives in appendix). 2). Clean and align your drives according to manufacturer specifications. Configuring 5-1/4" & 8" Disk Drives for the LNW80 Disk drives and cables which are configured to run on the TRS-80 Model I are fully compatible with the LNW80. Any eight inch drive which is Shugart compatible should run on the LNW80. If you are about to purchase drives and are unfamiliar with the concept of drive configuration, Appendix B should set you straight. Proper configuration for drives and cables should be provided by your computer dealer. Connecting a 5 1/4" Disk Drive Disk drives are connected to the computer's disk interface with a ribbon cable. 5-1/4" drives require a 34-wire cable with a card edge connector at each end. The drive cover must be removed to connect the ribbon cable. It is a good idea to fit the drive with an extender cable so that connection and removal are made easier. Table 5.0 - Pin specifications for the 34-pin 5-1/4" drive bus. The unlisted pins are used as grounds.
Pin # Description
2 Not Used
4 Not Used
6 Not Used
8 Index
10 Drive Select 1
12 Drive Select 2
14 Drive Select 3
16 Motor On
18 Direction Select
20 Step
22 Write Data
24 Write Gate
26 Track 0
28 Write Protect (Active Low)
30 Read Data
32 Side Select (Dual Sided Drives)
34 Not Used
Figure 5.0 - Extender Cable

Connecting an 8" Disk Drive Eight-inch drives require 50 - wire ribbon cables for operation, You will notice that the disk interface on the computer is made for a 34-wire cable (17 connections on each side). A 50-to-34 adapter board is available from LNW (stock# 1096) to connect the 8" drive to the 34-wire cable. One end of this board plugs into the 8" drive cable-connector (50-pin), the other into the 5-1/4" drive cable-connector (34-pin) as shown in Figure 5.1. If the connector on the 34-pin cable has pins pulled, you may only connect one 8" drive per adapter. Otherwise, the drive select process will not be able to "see" any 8" drive after the first one it encounters. If the cable is not of the pulled pin type, then you may connect a few 8" drives to the 34-pin cable using just one adapter. Figures 5.2 and 5.3 outline the rights and wrongs of the matter. Figure 5.1 - 34 to 50 Pin Adapter

Figure 5.2 - Pulled pin cable and 8" drive

Figure 5.3 - No pins pulled cable and 8" drive hook-up. Table 5.1 - Pin Specifications for the 50-pin 8-inch Drive Bus

Pin # Description
2 Ground or Lower Write
4 Not Used / Reserved
6 Not Used
8 Not Used
10 Two Sided (Not Used)
l2 Disk Change (Not Used)
14 Side Select (Dual-sided drives)
16 Activity / In Use
18 Head Load (Not Used)
20 Index
22 Ready (Not Used)
24 Not Used
26 Drive Select 1
28 Drive Select 2
30 Drive Select 3
32 Drive Select 4
34 Direction Select
36 Step
38 Write Data
40 Write Gate
42 Track 0
44 Write Protect (Active High)
46 Read Data
48 Not Used
50 Not Used

   In the RARE event that you haVe  an  8"  disk  drive  which 
requires  the  "write  current"  line  on the disk drive to be 
driven when using double-density above track 43,  the  adapter 
requires a small modification. A jumper cable (LNW stock# 
1097) must be soldered between TG43 on the  adapter  board  to 
pin  2  of  the 50-pin bus. Test out your drives first, and if 
you're having trouble above track 43  in  double-density,  get 
out the soldering iron!

Disk Drive Set-up and the 5/8 Switch

   The    layout  for  a typical disk drive system is shown in 
Figure 5.4.

Figure 5.4 - Typical Disk Drive System Showing
             Mixed Drive Setup & 5/8 Switch

5-1/4" or 8" disk drives may be used together in a mixed set-up, although you must make the computer aware of the size of drive zero (whether it is 5-1/4 inch or 8 inch). You do this by way of the 5/8 Switch, This is located in o recessed position above the cassette jack on the I/0 panel. The information relevant to this switch is shown in Table 5.2. Table 5.2 - Drive 0 and the 5/8 Switch

Drive 0 Type5/8 Switch
5-1/4 InchTowards Floppy Port
8 InchAway from Floppy Port
Disk Description

   The    names    "disk"    and    "diskette"   have   become 
interchangeable. Formerly, "disk" was reserved to describe the 
large  rigid  disks  associated  with  bigger  computers,  and 
"diskette" was  used  to  describe  the  smaller  flexible  or 
"floppy" disks of microcomputers.

   Refer to Figure 5.5 for a graphic description of the disk.

Figure 5.5

1) Protective cover - should not be opened. 2) Read/write opening. It is through this aperture that data is read from and written to the disk. 3) Write protect notch. In the case of 5 1/4 inch disks, covering the notch with an opaque label protects the disk from being written to accidentally. The reverse is true in the case of 8 inch disks - no label gives write protect status. 4) Timing aperture. The disk also has a small hole in it. When the disk is rotating, each time the hole is aligned with the timing aperture, a beam of light passes through. This triggers an electronic signal, letting the computer know that the disk has made one revolution. 5) Disk label. Use only a felt-tipped pen when writing on the label. Ballpoints and lead pencils may leave impressions on the disk. 6) Disk envelope. Inner lining helps to keep the disk clean. Floppy disks are made of a thin plastic material which is coated on one or both sides with a thin, uniform layer of metal oxide. Data is stored on the disk on concentric tracks, which are arranged on the disk by the read/write head of the disk drive. This process is called formatting, and is carried out under control of the disk operating system (DOS). The number of tracks is optional, but is usually 35, 40, 77 or 80. The tracks are numbered from the outer edge inwards. Each track is divided into sectors. The number of sectors per track depends on the DOS used to format the disk and whether single or double-density is involved. Most TRSDOS-like DOSes use 10 sectors per track in single-density and 18 sectors per track in double-density, Figure 5.6 clarifies this information. Figure 5.6 - Sketch of disk, tracks a sector.

Disk Care - Keep disks away from magnetic fields. Many domestic appliances have transformers which are capable of generating a magnetic field strong enough to erose all or part of a disk. Refrigerators, telephones a TV's are among these. - Avoid touching disk surface. Keep the disk in its envelope when not in the drive. - Remove disks from drives before turning drives or computer on or off. - In dry climates guard against static. Ground yourself by touching something metallic before handling disks. - Store disks standing on edge (not flat). - Store in a clean, dust-free environment between 50 and 125 degrees Fahrenheit (10 - 50 degrees C). Avoid leaving disks in the sunlight. Next page | TOC