RE: EPP or ECP based data transfer

From: COPLIN, Nicholas. (
Date: 2000-01-07 10:26:20

> (Are there any commonly used addressing schemes for bigger memories?)  The
> transfer speed would be limited by the PC.  At 1 MB/s, a cartridge image
> could be transferred in a 1/256 of a second.
[COPLIN, Nicholas.]  From memory the VCS emulator for the PC (MSDOS)
includes some instructions on how to set parameters and lists hardware types
for some of the biggers carts - I'll see if this has the info you may need.

> I still haven't found an easy way to power the 74LS74 in the PC<->PET
> transfer cable.  Does anyone have the power specs for 74LS74, 74HCT74 and
> CD4013?  Could any of them be powered through some (possibly several)  
> lines on the PC's parallel port?  Does the IC survive without damage if
> its Vcc is inadequately low (say, 1 volt) and some of its inputs are
> higher than Vcc (5 volts)?
[COPLIN, Nicholas.]  I've build a kit A/D interface which got power from the
LPT port by wiring together all data lines after putting the signals through
diodes. You have to program the data lines as "1" of course.  The voltage
drop means you get less than 5V, but didn't matter for this particular
circuit. My guess is if you use the 74HC chip you might get away with it.
The notes also warned though that the method is very LPT card specific as to
what voltage you get.  The other places to consider (no as neat admittedly)
are KeyBoard plug and Joystick/Midi ports.

[COPLIN, Nicholas.]  - Nick 


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