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Looking for alternatives to replace an FCode ROM on SBus Quad Ethernet

epakai

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Joined
Mar 11, 2023
Messages
3
I've got a Sun Sbus quad ethernet adapter (X1058A, 501-2602) that I booted in my Sparcstation IPX and Sparcstation 20. Both report "Invalid fcode start byte". It seems my ROM is corrupt.

I went ahead and dumped the ROM, and ran 'detok' (from fcode-utils) to translate the binary back to forth and it reports:
Code:
version1   ( 8-bit offsets)
  format:    0x03
  checksum should be:  0x2eef, but is 0x2f02
  len:       0x3adc ( 15068 bytes)

I didn't spot anything wrong in a browse through the source (~4500 lines of Forth), but I've never touched Forth, and I couldn't find a suitable linter to give me a hand. While looking around I did find a lot of the original source in the book "Writing FCode 3.x Programs", but a number of headers aren't included. Maybe I could spot the error by comparison, but the detokenized code isn't 1:1 with the original code.

I thought about just updating the checksum and having a go once I get a spare ROM.

Unfortunately I can't buy another working card at the moment, but I thought I'd ask here for other ideas or the chance somebody has one and could dump theirs.
 
Do you mean 501-2062 rather than 501-2602? (A google for 2062 brings up SQEC/S and X1058A)

I have such a board (marked "06 REV 50" on the SBus connector) with a socketed TMS27PC256 marked with the Sun part code 525-1351-02.
I should be able to pull the OTP EPROM out and read it on an EPROM programmer (assuming my PLCC to DIP adaptor works).

mdog69
 
Sorry, mis-wrote the number. Thanks for the ROM image.

Unfortunately this is the exact same as mine, detok still reports a bad checksum:

Code:
$ detok 525_1351_02.bin |head
version1   ( 8-bit offsets)
  format:    0x03
  checksum should be:  0x2eef, but is 0x2f02
  len:       0x3adc ( 15068 bytes)

$ md5sum 525_1351_02.bin quad_ethernet_fcode.bin
862e4059b7a45ca9aa1b145b65e91622  525_1351_02.bin
862e4059b7a45ca9aa1b145b65e91622  quad_ethernet_fcode.bin

I'm not sure where to go from here. Both my machines are running the latest PROM (IPX: 2.9, SS20: 2.25R). Neither would enumerate the card in OpenBoot.

I guess I need to just load an OS and see if the card can be used anyway.

Thanks again for providing another data point.
 
Last edited:
Is there a serial eprom on the board that holds data like serial number, etc?

I don't see any other programmable chips. There are a couple MCM62940BFN14, that I think are Cache SRAM, but I couldn't find an actual datasheet.
 
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