For the record, I did end up successfully upgrading a 2M REXCPM to 4M
using the RMLV3216AGSA linked below.
The only special note other than "how to desoldering alloy" and "how to
drag solder" was that the epoxy holding the copper on the pcb is weak.
Be exceedingly gentle wicking up the desoldering alloy, don't scrub, and
even with gentle wiping, only move in the same direction as the the
pads, don't wipe them sideways. Blot-lift-move-blot instead. One of the
teeny pads for the sram shifted sideways on me even though I was being
careful. I was able to nudge it back into place eeeeeever so carefully
without breaking the trace and solder the new chip.
Other than that it was straightforward. The pin-1 corner is marked on
the silkscreen, and there was nothing special to do, just solder the
chip and load the same firmware, only using the 4M cpm file.
Thus do I publicly waive any hint of warranty on my rexcpm. ;)
Also the dlplus bootstrap option can be used for rxctst.DO too.
dl -b./rxctst.DO and RUN "COM:98N1EN" and it runs all the tests
on the rexcpm.
--
bkw
On 6/29/20 9:29 PM, Brian K. White wrote:
$56 for a single
https://www.digikey.com/product-detail/en/cypress-semiconductor-corp/CY62177EV30LL-55ZXI/428-3278-ND/2188331
This looks compatible for $26 for a single
https://www.digikey.com/product-detail/en/renesas-electronics-america/RMLV3216AGSA-5S2-AA0/RMLV3216AGSA-5S2-AA0-ND/9650085
$32 at Mouser
https://www.mouser.com/Semiconductors/Memory-ICs/SRAM/_/N-4bzpt?P=1z0w8ge
It even seems to have a lower standby current. The Cypress data sheet
says 3uA and the Renesas says 0.6uA
If I buy one of these myself and solder it, will that be enough other
than re-programming?
$26 is a lot, and I wouldn't expect you to buy 100 of them for $2400
but, if I want it, and assuming a perfect solder job, is there
anything else besides a reflash required to make it work?
Obviously, it's a given that all concept of warranty and liability
goes out the window instantly.
--
bkw
