20 Dec
2007
20 Dec
'07
12:50 p.m.
Whether it uses drums, disks, or ultrasonic delay
lines, my challenge
is:
1) To build a complete functional computer, including memory,
Are things like core-on-a-rope ROM allowrd?
using no more than 256 2N2222-ish transistors (plus
scads of diodes,
resistors, etc.).
Do all transsitors have to be of the same flavour, or could I use TUNs
and TUPs?
I think I'd start by readign the schematics of the HP9100. It contains
more transistors than that, but it's still amazingly simple.
Anyway, the flip-flops in that machine were JKs, using 4 transsitors
each. The inputs are current-operated (direct onto the base of the
transistor). The loric gates use just diodes and resisitors, remeber you
get Q and Q/ from a flip-flop, which can really save inverters.
2) Use no ICs or other parts that wouldn't have been available
to hobbyists ca. 1965.
So that preumably means a multi-layer-PCB acting as an
inductively-coupled ROM is out. Rats!
3) Must be transportable in the boot of a mid-size sedan (i.e.
Totally OT, but I find 'boot of a sedan' a somewhat odd expession. 'Trunk
of a sedan' or 'boot of a saloon car' would seem more natural.
-tony