Which paper tape hole is bit 1?
ard at p850ug1.demon.co.uk
Sat Nov 19 18:48:07 CST 2005
> As it turns out Hole 8..1 corresponds on a PDP-8 to data bits
> 4..11 respectively (more significant to least significant). I was
> surprised since I expected the hole numbers to increase directly
> with the data bit number.
That's exactly what I'd have expected. It puts the 'holes', in order, in
the low 8 bits of the machine word.
> The punch is now hooked up (correctly) via my homebrewed driver
> card to the PC8E interface, and merrily spews chad all over the
Any chance of schematics being posted somewhere? I have a PC8e linked up
to my homebrew PC04 (well, converted from a PC05...). But I also have a
Tally 420, and I'd like to give it a go sometime.
> floor at high speed! I can email an Eagle schematic/board layout
> for the drive card if anyone wants...
Please don't e-mail them to me. Can they go on a web page somewhere?
> Now looking for a Tally 420 chad bucket :)
I have one, but it's not spare, if you see what I mean.
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