Tony Duell wrote:
CL kits. These were computer educational kits.
The basic module was a
plastic box with 3 input sockets, one output socket (with a lamp to
monitor the sate) and 8 'programming' sockets. By wiring up the latter
appropriately you could get the module to act as any 3-input gate. If
you wanted a flip-flop, you could either corss-couple 2 modules, or feed
the ouptut back to an input on the same module programmed as an AND-OR gate.
I assume this is transistor not relay logic.
Actually, it's TTL chips. IIRC the kits came out in the mid-1970s.
There's a schematic of the logic module in the manual (one of the frw
pages I can understand, since the manual is in German, but a schematic is
much the same in any language). There are 3 chips in the module, all with
Philis-type numbers. An FJH241 (looks like a 7404), FJH151 (7451) and
FJH231 (7401)
Here's a breif circuit description :
Call the 3 inputs A, B, C. They each go to a chain of 2 NOT gates ('04),
producing buffered A, A/ B, B/, C, C/ signals. C and C/ go to programming
sockets (outputs) on the module. 2 other programming sockets are '1'
(left open, this module makes the worrying assumption that a floating TTL
input is a '1') and '0' (tird to ground).
The next stage uses 2-wide 2-input AOI gates. For each gate, onr AND gate
is eanbled by B, the other B/ The other inputs to the AND gates (4 in
total) got to the f1...f4 prgramming sockets. The outputs of the AOIs go
to a pair of '01 gats, the other inputs of those go to the A and A/
signals. Then the outputs of those NANDs are commoned (and pulled up by a
resisotr), that then goes to another stage ('01s again) where you can
connect a capacitor to slow the module down (to make a clock oscillator,
for ecxample), then to the F output socket and to the transitor that
drives the lamp.
To summarise, most the module is a 4-input mux controlled by the A and B
inputs, with the output going (via a delay) to the F output. The inputs
to the muc are the f1...f4 programming sockets. You patch those either
high, low, or to C or C/ in the well-known way. So you can make any
3-input gate from the module.
The section immediately befroe the schematic in the manual gives the
method of working out the pathing for a given logic function by drawing
up the truth table, dividing it into pairs of lines, then calling a pair
that's 00 a low, a 11 a high, a 10 a C/ and a 01 a C. Then patch
appropriately. Or at least I think that's what it's saying, as I said
it's in German.
For most of the later experiments in the book you get separate diagrams
for the patching of each module and the wiring between the modules. Also
it appears you get an explanation of _why_ the patching is done that way.
In the back of the manual are some sheets which I think you were supposed
to cut out and put on the modules. They give a patching diagram for a
particular gste and a diagram of the conventional gate symbol and name
with the input and output lines extended to the sockets on the module (if
you see what I mean).
It appears there was another module, included in one of the add-on kits
(I don't have one). It was yellow in colour, but otherwise looked the
same as the logic module. In fact it contained the same logic circuit.
but with a msall relay in place of the lamp. The contacts of the relay
were wired to a 3.5mm jack socket mounted in the 'lamp hole' on the
module case, you got a cable with a suitable plug on one end and bare
wires at the other in the kit. It appears you could use that to control
small lamps, motors, etc from your logic designs.
Alas the smallest kit (all I have) only contaiend
2 logic modules and one
battery/input switch module, whuch wasn't enough to do much with.
That was the problem with all the computer trainers, they were too
small, even the ones with a cpu in them.
Well, 2 3-input gates (even arbitrary 3-input gates) was not enough to do
anything much (a single full adder was possible, not much more). If you
bought larger kits and the add-on kits I guess you could do a lot more,
some of the experiments in the book have 8 or so logic modules.
-tony