On Mon, 16 Apr 2018 21:40:21 +0100, Ahem A Rivet's Shot wrote:

>  A traditional set of blinkenlights is impossible, the bus lines
> aren't exposed where you could attach lights (and they switch a bit too
> fast).
>
Disagree: at least one microcomputer (the IMSAI 8080, as seen in the "War
Games" movie) had them way back in the mid-70s - and that was based on an
Intel 8080, so it must have been possible to write a firmware monitor to
emulate the effect of the handswitches and lamps on a PDP-8. However, the
8080 was an 8-bit chip with 8 nregisters and 16 bit addressing, so at
least the number of switches and lights was manageable.

But do it on a 64 bit chip with 16 32 bit registers and a 32 bit address
space? Some how I don't think so.

I have used hand switches to patch device drivers on 1900 mainframes (24
bit words, 22 bit address space) and that involved more than enough
switches as far as I was concerned.

If the OP wants a real challenge, I suggest he builds something like the
discrete transistor re-implementation of a 6502 that was recently donated
to the NMOC. However, since that's been done, why not tackle something a
little bigger and better, like a MC6809 MPU, but with at least one 6810
memory chip, 6820 PIA and 6850 UART. These would let the resulting wall
of LEDs interact with its visitors via contemporary devices like a Wyse
terminal and an Epson MX-80 printer.


--
Martin    | martin at
Gregorie  | gregorie dot org

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