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Old 8th February 2015
  #19
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^^^ Signal acquired. ^^^

So this is the front panel left PCB by itself? Sweet!

Quote:
Originally Posted by M.Retra View Post
I assume this serial connection using the RXD and TXD ports? I will need to check those ports for action.
Yes. 156250 baud, no parity, 8 data bits, 1 stop bit.

If it helps, it is pins 12 and 13 of the ribbon cable between the main board and front panel left board. The corresponding pins on the ColdFire are TXD0 and RXD0.

Quote:
Originally Posted by M.Retra View Post
The 87C52 used in the A6 (P87C52UBBB) is a one-time-programmable device. Any internal flash (8K) would be programmed once. ... And the EPROM chip cannot be reprogrammed without being erased with UV light.
There's also a 128KB SRAM chip specifically for the 87C52, so whatever payload the host processor sends probably ends up there.

Quote:
Originally Posted by M.Retra View Post
the SMD flash chip is the problem.
With luck, there's a device that can be connected to the debug port on the main PCB in order to read/write the flash directly, among other things.

Quote:
Originally Posted by M.Retra View Post
I always thought that EPROM's and other "flash" based devices are physically altered when programmed.
Just a hypothesis based on a few things I read. Would be interesting if we could resurrect a dead A6 by rewriting the flash, though.