On the FOCAL issue, I think I read that FOCAL can't
load text very quickly - you have to stop and start
the tape every line or two. I have noticed this with
my PDP/8e clone and not-very-fast (around 100 CPS)
paper tape reader. It may use its own intepreter to
store coding in RAM, so it might be very slow in this
area. If you can load FOCAL itself in via paper tape,
this kind of proves that the PTR itself is OK.
--- Ethan Dicks <erd_6502_at_yahoo.com> wrote:
> --- Megan <mbg_at_theworld.com> wrote:
> > Okay, it is a PDP-8/L, but I don't remember an
> -8/L with the kind
> > of paddle switches this one has... I seem to
> remember them being
> > the rocker kind like on a pdp-8/I
>
> All of my -8/Ls (3.5) have PDP-8/e-style toggle
> switches. My -8/I does
> have the rocker switches you describe.
>
> The 1970 Small Computer Handbook shows -8/Ls with
> paddle switches.
>
> Still a nice find, though. My -8/L is currenly my
> showcase machine -
> I fire up the ASR-33 and the PC04 (PC05?) and load
> FOCAL for folks.
> It was also my first-ever -8 - Dayton Hamfest, 1982,
> $35 + 8" floppy
> drive in trade.
>
> Got some minor processor glitch I haven't tracked
> down yet... I get the
> FOCAL prompt, but it won't load Hammurabi from
> either the ASR-33 or
> the high-speed reader. Most of the basic
> functionality is there - it
> runs an inchworm just fine. Once I fix the problem,
> I'll reattach
> the BM08 and bring it back up to 12KW and show
> people paper-tape BASIC
> and Star Trek (after I fix the tear in my
> floating-point tape ;-)
>
> When you get to debugging it and if you see any
> behavior that leads you
> to think there are hardware problems, after cleaning
> the card fingers,
> take a hard look at any 7474 chips. I rigged up a
> test clip to an
> automated IC tester to debug M-series modules out of
> the circuit (having
> never written any software to drive my VIC-20
> M-series tester) and
> found that the most common chip to die anywhere in
> the machine was
> the 7474 dual D flip-flop. Unfortunately, there are
> several of them
> in the M220 Major Registers modules and this
> simplistic tester isn't
> able to cleanly test them because of the multiple
> interconnects. I
> have a small box of "to-be-repaired" M-series
> modules from my -8/L
> collection. It's mostly M220s and M216s, with an
> occasional M160 and
> M111.
>
>
> -ethan
>
>
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Received on Fri Oct 11 2002 - 20:16:00 BST