1090 XL Expansion Box - 80 column card
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General information about the card and associated files...

Board contains a MMI PAL20L10. Actual markings on the chip are as follows:
PAL20L10CJS
8411  V80C11 (V80C11 is written by hand in white marker).

The file "exp80.jed" can be viewed in notepad and is the jedec file that was read from the PAL.

The file "exp80g.jed is a GAL conversion of the PAL chip to be written to a G20XV10. It was created by the:
PAL to GAL JEDEC conversion utility - paltogal v3.12  17 November 1992
Copyright (c) by LATTICE Semiconductor Corp. 1990, 1991, 1992.

Also included for ease of reference is the MMI PAL20L10 spec. In addition the 1988 AMD PAL Device Handbook.
http://www.bitsavers.org/components/amd/_dataBooks/1988_AMD_PAL_Device_Handbook.pdf

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Eproms - 

The file "80 col charset.bin" is at location U20. The original chip is a D2716 and the label looks like it says:
"58AE chrset" however the label is very sloppy. The A in checksum(?) looks very weird almost like it could
also be 58FUE. This eprom dumps with a checksum of A752. Verified on both readers I have.
This board hasn't been handled or exposed to light so it's my belief that the chip is valid and hasn't degraded.
Possible the label was wrong or not updated. Hard to say.

The file "80 col os rev9.bin" is at location U3. The original chip is a AM9716 eeprom and label says:
"E02F Rev. 9". This eprom dumped and checksum matched what is on the label.

There is a square 8 position switch at S1. This switch is set at position 3. Interesting that this switch has
traces going to the Rev. 9 eeprom chip. Not sure what it's purpose is.

There is a 3 pin jumper  next to the chrset eprom with center pin going to pin 19 of the chip.
One side is marked +5V and the other is GND. The jumper is set to GND.
