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

[J-F Garnier]

(03-18-2020 05:48 AM)Dave Frederickson Wrote:  

(03-14-2020 08:56 AM)J-F Garnier Wrote:  A few years ago, Paul Berger and I attempted to document it and identify the pinout, see this document:
http://www.jeffcalc.hp41.eu/misc/files/hhp.pdf

On p.4 of the document is a picture of an HHP card reader port EPROM module. How was this module programmed?

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. This is not true for CMT front port EPROM module, an erased module disturbs the HP71 operations.

J-F