Re[2]: A parallel interface for PET, VIC-20 and C64/C128

From: Frank Kontros (
Date: 1999-08-04 07:21:21

Hello Marko,

Tuesday, 3 August 99, you wrote:

Marko> True, but I think I'll try to build the universal cable.  I'll test it
Marko> first on the C64 and VIC-20, since my 8032-SK has an IEEE-488 like
Marko> connector for the user port.

Anyway welcomned. Would you also interested in diskcopier prg for
1541->C64/C128/C65->PC (I just remembered that sometime ago I promised
you send it).

>> At least you can connect all commies at once to one PC and serve all
>> at once.

Marko> If I had 3 bidirectional printer ports on my PC, yes.  Or 4, if I'll ever
Marko> get a similar interface for my C16.

You can use switcher or something similar if you lack of ports.


Marko> The schematic diagram doesn't mention the resistor values.

Because they're are removed from schematic. They makes much mess
than protect.

Marko>   The diagram at
Marko> <URL:> does.
Marko> I gather that the bigger resistors I use, the less likely it should be
Marko> that the interface chips get damaged.

>> Would be very nice if near complete line of C='s would communicate
>> with the same cable (with one PC :). The software's on C='s are
>> different, but same (or one?) on the PC side.

Marko> With careful design, you could make the software auto-detect on which
Marko> computer it is running. :-)

Hmmm. How? Eg. KERNAL patch. Make all routines in 3 or 4 versions?

Marko> The only unanswered question is: What is the DIAG pin on the PET user port
Marko> used for?  Can I safely program it as a '1' output and use it as a voltage
Marko> source for the 74HCT74 chip?

Don't know. Maybe you can source 74HCT74 from LPT port of PC too.

Best regards,

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