HP-71b CMT-64E Eprom - Whats under the black goop ?

[Dave Frederickson]

I know of at least 7 CMT EPROM programmers among forum members and three of the members who own them are participating in this thread.

The CMT EPROM Programmer won't erase chips, a UV light is used for that.

To test for an erased EPROM, use the CMT tool, PTBLANK$.

(03-18-2020 08:29 AM)J-F Garnier Wrote:  I did program HHP card-reader EPROM module back at the time, some for professional applications. The EPROM was programmed on a standard EPROM programmer, the only thing to know is that the bytes are complemented, I guess to make an erased EPROM (all FF) looks as zero bytes from the HP71.

I figured an external programmer was used because the card reader port can't provide the necessary programming voltage. I was more curious about how to create the EPROM image for the programmer. It sounds like all it takes is to dump an image from a 71, invert all the bits using one of the many tools available for manipulating EPROM images, and burn the chip and see what happens.

(03-18-2020 09:55 AM)KimH Wrote:  ROMs seem to be placed underneath the Card Reader area sort of Top Down regardless of which port they go into.

Not sure what you're saying here, but memory allocation for the 71 is well documented.


Dave