Communication with, and programming
the machine, takes place through a simple keyboard and display.
The most fundamental language - machine code condensed into
hexadecimal notation is utilised. Thus the system can be used
as an educational tool, or for the purposes of the professional
who has a need for a computer on the desk or bench top.
All the integrated circuits and components
required are included in the kit. Also provided are a printed
circuit board and a comprehensive handbook describing construction,
operation, and use. Since the unit is primarily a computer
it is designed not exclusively for the electronics expert,
but for anyone wishing to experiment practically with the
essence of digital computation.
Elementary competence in soldering
and printed circuit assembly is needed, but carefulness and
a methodical approach are the main requirements.
Central Processor Unit
The C.P.U. is a National Semiconductor
SC/MP microprocessor. It is suited to an ultra simple configuration
because although it functions without additional circuits
it has a general purpose architecture allowing system expansion.
Instruction types also conform with
the general purpose computer area, while special instructions
and architectural features such as delay timer and built in
serial and parallel input and output are particularly convenient
in a compact unit.
Fixed Memory and User Terminal
512 words of permanent memory contain
a monitor programme which provides the user with instant control
following switch on. By entering commands and data via the
keyboard and observing internal status and programme results
on the display, complete control and supervision is achieved.
Any part of memory or input/output
port can be examined and written to. All C.P.U. programmer
registers ie. Accumulator, Extension, Status, Programme Counter
and the three Memory Pointers are overseen in the same way.
Execution of a users programme can be started from any chosen
location and break-points (stops) may be inserted allowing
the user to analyse the progress of his programme.
The keyboard and display possess a
dual function the users programme is able to utilise them
for its own purposes.
Read/Write Memory
256 words of write-able memory are
included in the basic package. Keyboard commands allow loading
or examination of computer instructions and data in the same
sequence as the C.P.U itself uses. Thus, this part of memory
is where the user enters, and experiments with, his own programmes.
Note : some twenty words in this area are devoted to the monitor
function.
Provision exists on the printed circuit
for extending memory by two blocks of 256 words and 128 words
respectively (see input/output description)
External Input/Output
In order to satisfy the need for responding
to external commands and information, and for controlling
external circuits, a number of logic inputs and outputs are
incorporated with expansion capability. The basic unit possesses
an interrupt or data input, a data input, three signal outputs,
a serial input and one serial output.
Provision is made on the printed circuit
board for the optional addition of 15 lines of input/output.
Each line is individually selected by the users programme
to function as an input or an output. (This is part of the
same device providing 128 words of additional memory).
Training Manual
The manual consists of five main sections.
Electronic
Pulse Delay, Digital Alarm Clock, Random Noise.
System
Single Step, Decimal to Hex, Relocator, Serial Data Input,
Serial Data Output
Games
Moon Landing, Duck Shoot, Mastermind, Silver Dollar Game
Music
Function Generator, Music Box, Organ
Miscellaneous
Message, Self-Replicating Program, Reaction Timer
Peripherals
Tape Interface kit with software and
instructions. A low cost interface to any cassette recorder.
Prom Programmer for DM 74LS571 directly
driven from the MK14 and needing only an extra twelve volt
supply, this allows the user to programme fusible link proms
with his own operating system which can replace the existing
monitor.
Revised Monitor programme in 2 x DM
74LS571 - a condensed version of the existing operating system
but including sub-routines for tape interface - load and dump,
single step and offset calculation, and having single keystroke
data entry. (This can only be supplied as an extra as the
manual refers to the standard monitor).
The handbook is designed to enable
the non-specialist without prior electronic or software knowledge
to get to grips with computing as well as to satisfy the need
of the better informed for a basic user manual.
Science
of Cambridge Ltd.
6 King's Parade, Cambridge
CB2 1SN.
Telephone Cambridge (0223) 311488
