Electronics > Repair
Rohde & SchwarzSMS/SMS2 Microprocessor Board, where is the code/firmware stored?
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RichardM:
Hi All,

No responses from the R&S forum so thought I would try here :)

After successfully repairing an old SMS unit I could not help myself and purchased a spares unit. It was appealing as it had the oven oscillator option as well as the 1040MHz option which my working unit does not have.

Anyway, I knew it was not working but thought I would at least try to power unit up and do some initial testing to see if it is repairable or not. This unit has a different Y11 microprocessor board (302.7111) versus my other unit that has 302.7057. This Y11 board has Intel P8049AH and P8355 IC's. I have identified there is a fault on this board and suspect it may be either to P8049 or P8355. I believe these both have masked rom but I am not certain. My question is, where is the R&S SMS firmware stored on this version of the Y11 ? My working unit has a UV EPROM. Is it on both the P8049 or P8355 ? or perhaps one of them ? The P8355 has a sticker with 302.7257 which suggests it may be stored here ? The other question is if either chip is dead then I guess the unit is not repairable, assuming the firmware cannot be read out or re-programmed ?

Richard
fzabkar:
P8049AH has a 2K x 8 ROM (page 101)
http://bitsavers.informatik.uni-stuttgart.de/components/intel/_dataBooks/1988_Intel_Embedded_Controller_Handbook_Volume_I_8-Bit.pdf

8755/8355 is a 2K x 8 EPROM/ROM with I/O (page 406/413)
http://www.bitsavers.org/components/intel/MCS80/98-153D__MCS-80_Users_Manual_Oct77.pdf

Years ago I managed to dump a faulty 8355 and then reprogram an 8755. I suspect that one of its I/O lines was bad.
RichardM:
Thanks.

How did you manage to dump the contents ? I have a an old Willem programmer working via parallel port and I have just etched an adapter pcb for the P8049AHto try. If there was an easier way to check the P8049AH that would be great. :)
Tom D:
The P8049 on my 7111 board also has a sticker on it (302.7234). Although I wouldn't bet the farm on it, I suspect the firmware is in the masked ROM in the P8049 microcontroller. If you can extract the ROM contents of the 8049 chip, the contents can be programmed to an 8749 EPROM to take its place.

Tom
fzabkar:

--- Quote from: RichardM on September 05, 2023, 11:33:03 am ---How did you manage to dump the contents ?
--- End quote ---

I used to have a Sunshine Expro-80.
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