Digital Input and Digital Output Module not comatible with CP/M

[gfcwfzkm]

Well, as the title says, both Modules (the ones with 3 Ports) are not compatible with CP/M, not even if you try to Change the address.

No matter how I try to Change the address lines, either the Paged ROM, the Serial I/O or the Compact Flash Card are on those lines too.

Maybe I am just missing something. Some "more advanced" address Decoding would be nice..

[gfcwfzkm]

The easiest fix to make all the Input / Output Modules CP/M Compatible:

Solder 6 diodes from A2 to A7 (anode-side), connect the cathode side together and solder it to that empty address pin Close to A6/A7

Add a Pull-Down resistor of 4.7k from that pin to GND and boom - every address-line that is active except for A0 and A1 will disable the Digital Input, Output or I/O Module

Cheap and simple Address-Decoding ^^

(See pic, every second LED is turned on, sadly not well visible due to the camera Flash.

[Spencer Owen]

That looks wonderful! And certainly much more elegant (and cheaper!) than the ideas I had been coming up with.

I'll have to bust out the soldering iron tomorrow and give this a test.

Spencer 

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[gfcwfzkm]

A personal wish if you make a new Version / fix the existing Modules...

I would add that Diode-logic for every Module that uses IORQ. Basically also for the "Serial Module", "CP/M Module" and "Pageable ROM" Module.

Diodes cost nothing today and they are small but in this case here they finally bind certain modules to the correct, specific addresses.

Check this page for the Diode-Logics. If you Need more Advanced logics for low Price, check the "Diode-Transistor Logic" Page

Diode Logic or Diode-Transistor Logic

[Peter Fielden-Weston]

I just soldered the address links to A1 & A2. Now CP/M works fine and the digital output (the only one I've tested,) works great on IO addresses 3, 6, & 9.

Peter