Side trip

Before starting to wire up the IIcmxp I have been doing a lot of thinking about various aspects of  the project. Should I be doing 5v or 3.3v design … could I somehow use make use of other types of ram or fixed storage ….

I decided to back track a bit and began building a simple offboard expansion card. A six inch ribbon cable joins 2 IDC 34 pin connectors that attach to a 90deg IDC conenctor on some perf board and the IIc+ memory exansion connector.

 I mounted a 44in PLCC socket, a six pin header for JTAG access to the CPLD, a 5v to 3.3v DC-DC voltage regulator a button, a led and a occillator. I use wire wrap to join stuff together. For this experiment the IIc+ just provides power.

Loading up the sample state machine app that comes with the XC2-XL digilent board  functions as expected. Pressing the button cycles the leds in different patterns.

Next I plan to wire up the address bus and data bus so I can experiment with the creation of the /devsel and watch whats going on with the Logic analyzer.

Front Side Development Board

Backside of Development Board

3 Responses to “Side trip”

  1. Nick Westgate Says:

    How about some pics to accompany your explorations? It would be nice for those of us who know just enough about hardware to be dangerous (!) looking and learning over the shoulder of a pro.


  2. a2retro Says:

    A pro I am not … lets learn together then shall we … heres probably an example of how not to wirewrap a board – pretty messy huh …

  3. Nick Westgate Says:

    Thanks for the pics. Quite illuminating, although yeah – the wirewrap looks pretty hard to keep in your head.


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