HP-35 Serial Number Question

[Didier Lachieze]

The 1143A comes likely from the first pre-production units built end of 1971 before the official HP-35 launch date on January 4, 1972.

This date code was not changed every week but only when significant changes occurred in production (the next one was 1230A), or when reaching the end of the 5-digit serial number within the range.

See An HP-35 Production Overview for more details.

Note: looking through my HP-35 database a 1143A 41k unit was likely built beginning of August 1972.