Hi charlyd,
I can unfortunately not help out with firmware. I myself would be interested in the latest versions for pre VAR8 boards..
To hopefully not let you make wrong conclusions, I am pretty sure your CPU board is a
VER 10 (and not a VER3).
There is a bug in the boot ROM that does not show VER 10 but only a colon ":" instead. See also 5.93 release notes and readme file:
This firmware ist especially for the front module option SM-B50,
(fast CPU, BOARD VAR 8 or higher; "VAR 10" could be displayed as "VAR :"
due to a small bug in the boot eprom)
So given your information and the picture, the firmware should actually be the right one. From my (probably limited) experience, R+S error messages are pretty reliable: "FLASH EPROM missing".
-> I would focus to find out why the unit thinks the EPROM is missing. Wiggle the extender board, clean the contacts from possible oxidation, check if the flash chips are alive, consider soldering in replacement flash chips in case they turn out bad..
Not sure I understand the point about the AM27C1024 your friend has given to you. If I am not mistaken AM27C1024 are CMOS EPROMs - the PLCC version is one-time programmable. It should contain the bootloader and cannot be upgraded/reprogrammed... No accidental overrwriting can take place here.
Given the above, and considering the bootloader, residing on a ROM, is giving the right error code, I would bet there is contact issues with board connectors and/or the 2M Flash memory are corrupt and need to be changed.
Let us know if this helps. BR ick