Continuing this month's special look at home computers,
Sue Eisenbach tests a new machine
Rumour has it that when Texas Instruments was designing its personal computer, it knew that producing a colour signal for English and European TV would cause difficulties and so it approached a Belgian firm, Data Applications international (DAI), to design a European microcomputer. The brief was wide - using Texas components, produce a personal computer with sound and good colour graphics that may be used with domestic televisions. By the time the DAI personal computer was developed, TI had had a change of heart: it decided to market the 99/4 in Europe with an American colour monitor - which increased its price but solved the 'European problem'. DAI was left holding a computer, the design of which had been funded by TI... and it is this machine that Data Applications [UK] Ltd has now launched onto the British market.
The DAI personal computer is a single
board based around the 8080A micro-
processor. It's contained in a smart
white lightweight case, which also holds
the keyboard and is held together by
four black plastic pins which can be
pushed in or out by hand.
scan and encoder.|
The DAI has an external connector for a flat cable to the DCE bus the bus used by Data Applications' other bus-based computer. According to the manual this bus can also be used for connecting up to a parallel printer. There's also an RS232 connector on the back of the computer.
The dynamic RAM is divided into three separate memory banks which can contain 0, 4k or 16k of RAM, The RAM is seen by the program as a continuous memory block starting at 0000H. The first RAM bank (which may not exist) is for programs, while the second two are used for both programs and display data. The second two banks contain the low order and high order bits of the 16-bit words needed for the display. The RAM configurations allowable are 8k, 12k, 32k, 36k and 48k.
The Basic and other system software sits in ROMs starting at address C000H and extending to EFFFH. Addresses E00H through EFFH have four switch- able banks of program address space giving a total ROM address space of 24 kbytes. Static RAM occupies the address range F800H to F8FFH which is used by the 8080A for stack space while the top of the address space is used for memory-mapped I/0.
The DAI has five programmable interval timers, two external interrupts and two serial I/0 interrupts. According to the manual, it has the appropriate circuitry for connecting two games
paddles as input devices. Each paddle contains three variable resistors whose positions are read as values and one on-off event.
On power-up, DAI PERSONAL
COMPUTER appears in large white
letters on a bright green background;
hitting any key clears the screen and
puts BASIC V1.0 in small black letters
on a white screen. The Basic occupies
24k and although written by DAI,
shows a strong Microsoft influence, as
can be seen from the table of Basic
CALLM N, [V], which calls a
machine language routine located at N.
If the second parameter is included in a
CALLM statement, then the HL register
pair will contain the address of variable
V. Upon return all 8080 registers and
flags are restored to their original state;
translated into an intermediate code
that is faster to execute than the Basic
statement typed in. Usually a 'semi-
compiling' Basic will not accept a line if
it contains errors since it cannot
translate it into intermediate code. This
can be quite irritating if you have to
type a long line again because of a silly
typing error but DAI Basic has got
around this problem. When an incorrect
line is typed in, an error message
immediately appears. When the program
is listed, the erroneous line is there but
has *** in front of it. These can be
easily edited out when the line is
corrected in the editor.
The DAI personal computer has three
graphics definitions available (low,
medium and high resolution) as well as
an all character mode. The character
mode displays 60 by 24 characters. The
graphics definitions are: low - 65 x 88
pixels; medium - 130 x 176 pixels; high
- 260 x 352 pixels.
changed at will, and the existing picture
changes colour immediately) and can
use any of these colours anywhere on
the screen. In a 16-colour mode, the
screen is divided into vertical fields 8
pixels arrows. Within each field only two
colours can he used.
SoundThe DAI can generate sound using three independent programmable oscillators and a random noise generator. Each of the oscillator channels can be programmed to produce sound in the frequency range 30 Hz to 1 MHz at whatever amplitude is required. The noise generator which produces random frequencies is designed to simulate white noise and to provide a random sequence for random numbers. Oscillator channels one and two are used to produce sounrl for the left stereo output while channels two and three are used for the right stereo output.
A music program 'Music Tutor' came with the review machine. When run, staves appeared on the screen and the
typing keyboard became a musical
keyboard. Hitting a key produced both
a sound and a note on the screen.
Although not a sophisticated piece
of software (all notes were crochets) it
did demonstrate some of the potential
of the DAI's sound capabilities. The
bottom row of keys became a piano's
white keys while the next row up con-
tained the black keys. Pressing a key in
the next row produced a chord while
the top row was used to alter the
quality of the notes produced. By pres-
sing a key in the top row the volume
could be increased or decreased or the
duration of the notes hit could be
altered from normal to either staccato
or an organ-like (filled with overtones)
NOISE ENV VOL
The documentation comprises two
books - a general introductory text
designed for someone with no
knowledge of computers and one
entitled Personal Computer Manual
which is more technical.
paginated and has an excellent table of contents (eg 'How to get Restarted if Accidental Reset During Program Keying or at End of Program'). The hardware sections contained justifica- tions for design features (such as the graphics resolution) which make for interesting reading.
The minimum system is an 8k black and white version with low and medium resolution graphics. This can be expanded to a system like the review machine; and with 48k and full colour graphics the single board is fully populated. There's a DCE bus connector which can be used to attach a DCE backplane and any number of DCE Eurocards, which include EPROM, RAM and a wide range of I/0 cards,
In common with the other European
machines that I have reviewed, the DAI
personal computer has rather nice
system software but no applications
packages. At this stage the DAI micro
is only interesting to programmers or
people who want to learn to program.
the box is too fragile for school use.
Being limited to Basic makes this
machine unsuitable for teaching
programming at a higher level, yet it
may have a place in higher education as
a machine for monitoring and
I found the DAI personal computer an entertaining machine to play with. With its range of add-on boards, its potential as a computer for process control is good. Both its colour graphics and sound capabilities are impressive and would make an interesting proposition
for someone who wanted to produce
and record computer music.
48k - £795, 32k - £725, 12k - £595, Hardware Maths Module £149. All prices are exclusive of VAT and delivery charges.
Machine Language Utility Commands
Technical DataCPU: 8080A, 2 MHz
Memory: 48k dynamic RAM, 24k ROM, 262 bytes static RAM
Keyboard: 56 keys
Screen: Any colour TV, 60 x 24 char., 260 x 352 pixels
Cassette: Any audio cassette, 600 baud
Disk Drives: N/A
Ports: Input: 2 paddies, RS232; output: 2 stereo channels, RS232
System software: Machine language utilities
Languages: Basic, 8080 machine code
Benchmark Timings (in seconds)
Set up ***
Ease of use ****
HIGH LEVEL LANGUAGE
System Software N/A
Disk drives N/A
Disk drives **
VALUE FOR MONEY ***
**** very good