Vintage Calculators Web Museum - The Pocket Calculator Race - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Radio Wrangler · 13th Jul 2025, 2:42 pm

After the HP55 had come out, a sheet of paper circulated with details of how to upgrade an HP45 to a quartz crystal clock and to access the stopwatch functions formally introduced on the 55. The software was already in the rom, only a contact operating pip on one key was missing, but a three-finger poke accessed that without hardware change. It handily quoted the HP part number of the crystal and a moulded choke needed.

Of course, I did mine!

Reasonably accurate and a stopwatch with 9 split hands!

David

13th Jul 2025, 2:42 pm	#41
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 24,737	Re: Vintage Calculators Web Museum - The Pocket Calculator Race After the HP55 had come out, a sheet of paper circulated with details of how to upgrade an HP45 to a quartz crystal clock and to access the stopwatch functions formally introduced on the 55. The software was already in the rom, only a contact operating pip on one key was missing, but a three-finger poke accessed that without hardware change. It handily quoted the HP part number of the crystal and a moulded choke needed. Of course, I did mine! Reasonably accurate and a stopwatch with 9 split hands! David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done