Early (earliest?) HP-41C find.

[Diego Diaz]

A few days ago I get another HP-41C with a couple of modules.

Nothing unusual as I'm always looking for module shells/connectors for the Clonix & NoV's projects.

Upon a first inspection it was clear that this HP-41C has a pre-production s/n 1916A00066.

Previous documented earliest s/n from Richard Nelson is 1916A00078 here

The bottom cover has some cosmetic differences from the early production units:

No golden ball contacts. A couple of slots instead of holes for those balls.

The back label is made of painted aluminium instead of vinyl.

Also the colour of the cover is a bit more clear than the production units and the "U" frame between the upper and lower shells is dark grey instead of dark brown.

However the most "interesting" part was inside.

The CPU board was populated with ROM versions D, D, D. Chips 1LA315, 316 and 317. The last one was the unkown.

Earliest production run carries ver. D, D, E. Chips 1LA315, 316 and 322; soon replaced by 333 for bug #1 correction.

All the known bugs are present of course, and since such 1LA317 ROM2 (ver. D) was never on the wild, it's reasonable to imagine that some other(s) undocumented bugs are also present in this unit.

I'll be back home in a few days and will extract the ROM contents; in case someone is interested in fiddling with this pre-production ROM version, I'll gladly share the image so it can be used in some emulator... Just for the sake of curiosity. ;-)

Best from Caribbean.

Diego.