Tandy Logix-Kosmos (was: Re: Ferranti Logical Computor (1951) )

Tony Duell ard at p850ug1.demon.co.uk
Mon Oct 22 17:08:33 CDT 2007


> > My only real complaint with it as a teaching tool was that even though
> > I did all the projects, there was no abstraction of the underlying
> > concepts presented.
> 
> I agree.  They also didn't do a good job of clarifying that the
> device only implemented combinatorial logic.  As I recall, I got

THis is, alas, a major failing of a lot of the educational kits. THose 
n-in-1 electronics kits were poor at this too. Not only did they rarely 
give a proper explanation of the circuit operation, but in some cases the 
circuits were designed round the components in the kit and were quite hard 
to understand.

Possibly the best educational kits were those produced by Philips. There 
were the IR (Interphone Enginner) and RE (Radio Engineer) kits that 
assembled to make a 2-station wired intercom and an AM radio respectively 
(using screw terminals, no soldering), nothing more. But there were at 
least 3 other seires that I've come across : 

EE (Electronic Enginner). These were good in that you handled real 
components, they were not pre-mounted on the kit's baseboard. So you 
learnt the resistor colour code early on :-). The compoennts were 
connected together by spring terminals that you fitted to an insulating 
baseboard, orgiinally hardboard, later plastic. The early kits used 
germanium transistors with long leads that were connected up in the same 
way, later kits had transistors (and later still varicap diodes, FETs, 
LEDs, etc) on little PCBs that fitted onto the terminals.

You got some quite interesting components in the kits. THings like audio 
driver and output transformers, and a matched pair of transistors to make 
quite reasonable amplfiiers. IF transformers, oscillator coil and a 
2-gang variable capacitor to make superhet radios. (I think one of the 
later kits had a circuit for a varicap-tuned FM radio). One of the 
smaller kits made a auio-frequency signal generator using a pair of RF 
oscillators and a diode to mix them non-linearly, a larger kit made a 
wein brisge oscillator with a lamp to stabilise the gain. I am told (but 
never had) that one of the kits had a pre-mounted CRT (with a ready-built 
HV supply) to act as a simple 'scope, another kit added a TV tuner module 
so you could make a simple black-and-white TV (!)

Anyway...

ME (mechanical engineer) kits were plastic plates and disks + metal rods. 
You could put pins into the disks to make gear wheels, there was a small 
electric motor in the kit too. What made them more interesting (for the 
time, late 1960's) was that you could control the mechanical models 
(motor/lamps) using the components in the EE kits. So you could make a 
car that would turn on its headlights when it got dark or something.

And finally, to get this on-topic (sort of)

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.

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.

-tony



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