13 Aug
2006
13 Aug
'06
11:04 p.m.
On 8/14/06, woodelf <bfranchuk at jetnet.ab.ca> wrote:
I think if you are building a replica is to design
your own Flip/Chips
and build a clean design from scratch. A PDP-8/S does not look that
impressive, I know I seen one in the flesh once,as compared to a
PDP-8/e. If you go with 20 I/O pins, (and sneaky pcb pinout )a simple
GAL (SMT) could make up a generic card and be re-programmed for
what ever logic you want.
Yes, but in the case of a Straight-8 or PDP-8/S, the R-series and
S-series logic is utterly incompatible with TTL. The supply voltages
are +10V and -15V, and asserted logic is +3V or -3V, thus the reason
for staying with discrete SMT transistors.
The SMT GAL design could be useful for building an M-series machine
(-8/L, -8/i), but with that era of machine, the FLIP CHIP modules are
double sided, with 36 pins (32 signal pins and up to 4 power/ground
pins).
-ethan