"Joel Setton via groups.io" <setton@...> writes:
Hello Martin,
The EPROM idea is interesting, I have explored it but I don't think it
could work. The main issue is that the 8Kbyte RAM
chip which holds the calibration data (TC5564APL-15) is also used to
store the processor stack, firmware variables,
user's memorized measurements etc.
From the schematic, we know the RAM is used as follows :
- Calibration RAM data is from 0040 hex to 01FF hex with a special
hardware mechanism to prevent accidental overwrite of
this area.
- General storage RAM (processor stack, miscellaneous variables, user
measurement FIFO etc) from 0200 to 1FFF.
.... In summary, replacing the RAM chip with an EPROM would not
work. One (strong) reason is that the processor stack
and RAM storage would not be writable.
Using an FRAM might be a possible solution. A quick search showed that
there's a FM1608B vom Cypress - 8Kx8 and available in DIP.
