The first sign of HP-35’s ln(2.02) bug

[EdS2]

The archived site of the late Jacques Laporte says this:

Quote:In 1972 (probably by the fall of 1972) , when the problem was discovered, HP had sold some 25000 units, but only 5000 machines were returned to have their 3 ROM chips exchanged.

Bug free units were shipped starting January 1973 :
- Serial Number 1302AXXXXX (second week of 1973) and higher are error free,
- before that all units needed modifications.
The recall process started in February 1973: "We have taken immediate steps to correct the problem, and will have replacement read-only-memories available sometime after the first of the year" wrote Ron Stevenson Customer Service Manager, to the "Dear HP-35 Owner"