HP-71B developed before HP75C ?


"Although the basic card reader design was originally developed for the HP-71B, the first version appeared in the HP-75 computer".

This sentence appears on page 20 of the July 84 issue of HP Journal.

Can anyone explain this ?


There's nothing particularly mysterious about it. The 71B and 75 were each in development for a long time. It's my understanding that the 71B project expanded considerably beyond its original scope. It's not surprising that something developed for the 71B (possibly before the "71B" designation was even chosen) might have first shipped in a different product.

There's a long history of such occurrences in the computer industry. The transitor circuits and packaging and the core memory units IBM originally developed for their Stretch computer were first shipped as part of the 7090 computer in 1959, two years before the first Strech (7030) shipped.


Why there is the "B" in 71B? I assume that is from BASIC, but as far as the 75, the C was customary for CMOS Continuous Memory (The 75 C had BASIC too... but it evolved into the 75"D"...)


The HP-75C was actually almost introduced as the HP-75D. They changed the suffix to "C" at the last minute, and some of the publicity photos showed the "HP-75D" legend of a prototype unit. Some prototypes were marked "HP-75CX", and I think there were other designations as well.

It is not uncommon for the final name or model number of a product to be decided only weeks before product launch.

I've never heard any explanation of the "B" in "HP-71B", though "BASIC" is as good a guess as any. At various times HP seemed to adopt naming conventions, but they never stuck to them very well until the "S" for scientific, "B" for business, and "G" for graphing that they have used for the last decade or so.


And the HP71B was almost called the HP44 (another machine in the HP41 series...). There are copies of documents in the HPCC library that refer to the HP44 (and it's clearly the same as the HP71B that was actually sold).

Possibly Related Threads...
Thread Author Replies Views Last Post
  Battery replacement HP75C Chris H (UK) 1 804 08-05-2013, 11:02 AM
Last Post: Sylvain Cote
  HP-IL 71B to 71B via HPIL Geoff Quickfall 11 2,148 12-01-2010, 06:55 PM
Last Post: Michael Meyer
  HP75C Display (was zebra connector) Alberto Fenini 8 1,737 11-08-2010, 02:07 PM
Last Post: Thomas Klemm
  HP75C 82713A plug-in module simulator aj04062 1 639 11-04-2010, 09:34 PM
Last Post: Prabhu Bhooplapur
  HP75C Restoration (zebra connector ??) Alberto Fenini 5 1,271 11-01-2010, 06:47 AM
Last Post: Alberto Fenini
  Texas developed a RPN calculator in 1970's gileno 18 3,191 12-02-2008, 07:40 PM
Last Post: Don Shepherd
  Catalog Plus for HP75C/D Rev 2 gileno 10 1,892 08-03-2007, 06:55 PM
Last Post: Garth Wilson
  FAST ! HP75C GE 12 2,275 01-17-2007, 06:06 AM
Last Post: Maximilian Hohmann
  HP75C Prabhu Bhooplapur 1 625 07-24-2006, 02:45 AM
Last Post: Raymond Del Tondo
  HP75C service manual or some help to repair Prabhu Bhooplapur 0 468 07-17-2006, 06:29 AM
Last Post: Prabhu Bhooplapur

Forum Jump: