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Reverse Engineer SMS

We don't have schematics of some SMS cards -

and schematics are indeed helpful in understanding/troubleshooting cards

Rand Neff is making interesting images of SMS cards - inpart to help Reverse Engineering.

Rob Lion of Cal Tech suggests "A free schematic tool I've used some is ExpressSCH from ExpressPCB:"

"They have free tools for schematic and PCB layout, and while they're not as powerful as some (no autorouting), they're not bad to work with, and the price is right! It might get unwieldy for large circuits, but it looks like the individual cards are not _too_ complex."

Grant Saviers says

I've been using ExpressSCH for all of my analog board schematics and for some of the other misc TAU analyzer schematics.
Bob [Feretich] has been using a different tool, he might have some comments.

Express SCH Pros:

  • Free
  • seems bug free
  • pretty good component library, certainly most everything is discrete on the IBM cards
  • can define your own components
  • easy to move things about, rubber band connections, can cut and paste
  • pretty easy to learn
  • permits different page sizes
  • No net list out of SCH, I haven't tried the PCB, maybe it will produce one for checking the layout
  • proprietary file format, I use acrobat to output PDF's for interchange
  • unusual typeface, doesn't ocr well in acrobat
  • no ascii data input format I know of
  • I manually edit off the R,C etc indentification of resistors and capacitors
  • a few shortcuts can increase entry productivity
  • no 74HC in factory supplied library but some 74LS, so I change the names on the pin compatible parts
  • (I haven't been able to find any other libraries - does anybody know of some on the web?)
I've attached the most complex schematic for the analog board (1 of 3) which is mixed 74HC and discrete components


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