Need advice on dumping 80C51 ROM

I have an 80C51 equivalent IC chip, P80C521, and i think it has internal either 8 or 16K of ROM. no external ROM on the board.

Im familiar with Atmels and programming of atmels, but can someone point me in the right direction for a simple programmer/reader for this P80C521 chip? the chip is a display controller, no datasheet available for the display, so I need to dump the ROM so I can run it in a disassembler.

any ideas? thanks.

Reply to
Mike
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If I remember correctly, the 521, has custom ROM programmed at the factory. It is not externally accessable. The 541, has ROM that can be programmed. The chip manufacturer (AMD?), will probably still have the original ROM data, but will also probably still be bound by their original agreement not to disclose this. Your only 'shot', will be to find who the chip was programmed for, and see if they can help you.

Best Wishes

Reply to
Roger Hamlett

On Sat, 14 Oct 2006 14:14:44 GMT, "Roger Hamlett" put finger to keyboard and composed:

There is a datasheet at

formatting link

FWIW, the P87C521 might be an EPROM version of this chip. IME the existence of an EPROM version usually implies that the ROM version can be externally accessed.

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.
Reply to
Franc Zabkar

it doesnt have a window, so its ROM. man i wish i could dump this ROM and disassemble it to see how it works.

Reply to
Mike

The point being made, was that _sometimes_, if there is an equivalent EEPROM version, the circuitry to allow the ROM contents to be accessible to a device programmer is left in the die. If so, it might be worth tracking down the programming algorithm for the 87C521, and trying the 'read' part of it. Some commercial programmers will also still contain support for this device. For example, the 'ROMMAX' from Action Electronics lists this.

Best Wishes

Reply to
Roger Hamlett

Sometimes you can build an external rom "extractor". This code executes and reads internal code via MOVX instruction. However, I would expect that the internal rom has been code protected by fuses so I think this highly unlikely. It could be that ROM based cores are internally protected by default!!! In the old days, I was able to read 'protected' devices by gradually lowering the target vcc and trying to read the device with a conventional programmer.Specifically, this was a Philips device.....

Reply to
martin.shoebridge

ugh. sounds like a nightmare. I think i will just re-write the firmware for an ATmega and useing an ATmega and just trash that 8051.

:-)

Reply to
Mike

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