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Thread: Help identify old i8085 board (supposedly Xerox)

  1. #1
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    Default Help identify old i8085 board (supposedly Xerox)








  2. #2
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    Possibly a printer; those ROMs might be Postscript.

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    Quote Originally Posted by MikeS View Post
    Possibly a printer; those ROMs might be Postscript.
    Not from Xerox in 1983 with an 8085 processor

    Dumping the eproms might yield some useful strings

    I can't tell from the picture if there are RS232 driver/receivers on the connector in the lower right.

    The upper ones look like they are driving a peripheral interface

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    Quote Originally Posted by Al Kossow View Post
    Dumping the eproms might yield some useful strings
    Unfortunately, they are soldered to the board.
    Quote Originally Posted by Al Kossow View Post
    I can't tell from the picture if there are RS232 driver/receivers on the connector in the lower right.

    The upper ones look like they are driving a peripheral interface
    Nope, his marking SN7406 and SP8404 (74LS08?), also I don't see USART IC on the board

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    So, i desolder one EPROM from main board with strange marking:
    P1130733_измен.размер.jpg

    I dumped it with help programmer as 2716. Dump in attachment.
    Attached Files Attached Files

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    I desolder all chips from PCB marked "PAGED MMB 140P12268 A / 140S27530 B ED" and read it with programmer. Dumps in attachment.
    Attached Files Attached Files

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    Based on the board design and date, it probably came out of the division in El Segundo that did the Star (Xerox 8010)
    I'm guessing it is the print engine control board for their small printer (Model 4045). I have some service
    info that I haven't scanned, let me dig it out and see if I can find anything that looks like that.

    nope, not a 4045
    Screen Shot 2020-01-12 at 8.24.20 AM.png

    the other thing is the board has a lot of eprom, but not much ram which wouldn't make sense for a laser printer

    the eproms don't seem to have any text strings in them
    Last edited by Al Kossow; January 12th, 2020 at 08:27 AM.

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    Quote Originally Posted by Al Kossow View Post
    the other thing is the board has a lot of eprom, but not much ram which wouldn't make sense for a laser printer

    the eproms don't seem to have any text strings in them
    Thanks. The first dump from 2716 EPROM looks like 8085 code, first bytes mean jump to 0100h, then interrupts vector table, then startup code from 0100h location... Yes, no text strings in dumps... And don't remind raster FONTs, perhaps data bits and/or adress lines are bitstucked, i don't know...

    So, PCB has two types of RAM - four TC5501P IC (256x4 sram) - 512 bytes total, and three TMM2016AP (2048x8 sram) - 6 Kb total. Also, IC marked 733W02274-1 near gold ceramic 40-pin controller look like 16/32 Kb SRAM, or maybe OTP EPROM. I try to desolder it and determine its purpose.

    I plan to disassemble the board for spare 74LSxxx parts.

  9. #9
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    Quote Originally Posted by Al Kossow View Post
    Not from Xerox in 1983 with an 8085 processor
    It was just a wild guess; I scrapped a printer years ago (Xerox IIRC, could have been NEC) with a similar size board and a daughterboard with 8 or 10 EPROMs containing the Postscript interpreter.

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    Quote Originally Posted by MikeS View Post
    It was just a wild guess; I scrapped a printer years ago (Xerox IIRC, could have been NEC) with a similar size board and a daughterboard with 8 or 10 EPROMs containing the Postscript interpreter.
    in that time frame Adobe only had 68000 Postscript, and Xerox would NEVER have used it, since they had their own horse in the race (Interscript)

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