On Sun, 2008-05-11 at 16:25 -0400, Allison wrote:
Bob's SBC6120 is as close or better than a real 8e
for playing with code.
That s the point too. Emulation you just cant pay with wires or add
a parallel port.
Aha, I disagree. You can't get at the innards of the 6120 at all,
because it's a chip. If you want to get at the innards of an emulator
then you can, although how accurately the emulator models the logic of
the -8 might be an issue (my emulator doesn't model it at all, but
largely does its own thing).
Adding a parallel port is easy - you've got one on your PC. Work out
what you want to talk to the parallel port, and graft on a bit of code
to do it. Dead easy.
Need more ports, or a smart-ish peripheral? Get one of those
microcontroller boards with a USB device port and a bunch of IO lines.
The Arduino Diecimila looks pretty good for this, although having more
than one UART would be nice. The UART talks to a generic USB-to-Serial
chip (FTDI, for those interested) and you've got an assortment of
digital IO, analogue input and PWM lines to play with, and a bunch of
timers and things. It presents to the PC as a serial port, and you
program it in C. I reckon with one of them and a bit of interfacing
hardware (level shifters and latches, mainly) I could drive most PDP-8
peripherals (if I had any).
Gordon