Paper Tape reader.  Try getting a set of opto-isolators, and making your
own;  One opto clocks the whole rig, off the "sprocket" hole, software
PLL the whole thing off that hole, use floppy drive type stepper motors
to spin the takeup reel, and it should work fine, I'd think.  An 'F84
should do that easily (just don't rip the paper tape in half - used to
be able to get pretty high speeds off mylar tape this way, beat a KSR/33
<G>)

Paper tape punches, could make your own similarly, I'd think;  Should be
able to find a KSR/33 (or ASR/33 or ???) for not too much, though, at a
hamfest or surplus equipment sale or ???  I haven't been looking, for
those or for card punches, the local U.W. CDC machines were thrown out
in pieces about 1982 or so, sadly (What a fun toy a Cyber would make!
<G>)

Look into active termination for that bus, someone else here is the
expert but I'd guess that'll be needed instead of passive; you could
just build a cable and terminate it, load it with PIC chips, then scope
it & see (though SCSI hard drives seem to work just fine with a somewhat
longer bus, and identical cable, terminated.)  Maybe set every other
wire as ground, that should help.

  Mark

Keelan Lightfoot wrote:
>
> For quite some time now I have been designing a computer that looks like a
> mainframe from the early 70s -- Many toggle switches and lamps, and a large
> cabinet. It's CPU will be a Z80, but the CPU control panel will be
> controlled with a PIC. Basically, the system will be built out of about 5 8"
> high x 19" rack panels, 1 each for the Power-supply, RAM, ROM, I/O and CPU.
> I know this isn't directly PIC related, but, shucks, there are a bunch of
> smart people here :)
>
> My questions:
>
> 1) The system bus will need to be around 32 inches long. The CPU/bus will be
> running at 10 MHz. Will I have any problems? I am planning to use a 50 wire
> ribbon cable with 50 pin IDC connectors stopping off at each module (rack
> panel).
>
> 2) Where could I get toggle switches with wide, long, flat actuators, like
> those used on the PDP/8? I am looking for switches that will line up nicley
> in a horizontal row. I would need to have switches that support ON/OFF,
> MOMENTARY/OFF and MOMENTARY/OFF/MOMENTARY positons. I would prefer switches
> with a contact for the OFF position too, so that I can use a flip-flop for
> debouncing, rather than loading down the PIC with debounce timing.
>
> 3) Does anyone have a paper-tape reader for sale for a reasonable price? I
> wish I could use punchcards, but finding a punchcard reader that I would not
> feel guilty about butchering would be hard, and finding a punch card
> supplier would probably also prove problematic. (I can cut my own paper
> tape)
>
> I have been designing this thing for some time, and finally am accumulating
> enough money to build it. I want it to have incandescant lamp indicators,
> just because they will look more 'magestic' when the computer is running.
> The inside of the cabinet will be quite bare, as I am using semi-conductors,
> not vaccum tubes :) I am mostly building the cabinet for effect -- To have a
> 5' tall cabinet (I am going to have a dead 20" area on the bottom of the
> cabinet, available for future expansion) full of toggle switches and
> flashing lamps will be quite impressive :)
>
> The PIC in this system will control the programming interface on the CPU
> panel - It will take over the bus using the Z80's DMA facilities, where data
> can be manually entered into RAM using the toggle switches. The PIC will
> also control the system clock when it is allowed, so that code can be slowly
> stepped through for debugging. I think that a PIC will also control the
> paper-tape reader if I can find one.
>
> - Keelan Lightfoot