Support for Big(ger) Iron Display at HHC 2017?

Richard J. Nelson rjnelsoncf at
Sun Jun 25 16:54:42 MDT 2017

Hello Roger,

Here is the A vs B model answer from MoH. 

"The HP 9100A was introduced first with maximums of 16 storage registers and
196 program steps.  The HP 9100B came later with maximums of 32 storage
registers and 392 program steps. On both machines core was shared between
registers and program steps. (The 9100B had two pages of core labeled + and
-.  Gotos were assumed to go to the current page unless a + or - preceded
the address.)  The HP 9100B also added subroutines, a dual program display,
and a key to recall numbered registers into X."

"If the HP 9100B's memory space wasn't large enough, HP later introduced the
HP 9101A Extended Memory.  This rack mountable box of core memory provided
an additional 3472 program steps or 248 data registers.  It also provided
some new features including indirect addressing (with the X stack register
providing the address), storage arithmetic and protected memory.  This
option could be added to either model."

X < > Y,


-----Original Message-----
From: hhc-bounces at [mailto:hhc-bounces at]
On Behalf Of Roger Hill
Sent: Sunday, June 25, 2017 2:19 PM
To: Handheld Computing Conference discussion list <hhc at>
Subject: RE: Support for Big(ger) Iron Display at HHC 2017?

Hi all,

What was the difference between the HP 9100A and the HP 9100B?

I believe the first RPN calculator I used was the 9100B in 1970.  It stored
programs on roughly business-size magnetic cards (some of which I may still
have around somewhere), and it was connected to a very nice plotter.  I also
seem to recall that the line numbers for program commands were in base 14
(digits 0123456789abcd); never did understand why.

-- Roger

------------ On Richard Nelson's message ------------
Hello David et al.,

The HP9100 is especially important for HP Handheld fans from the HP-35A to
the HP-65.  See the attached article for the true story.  I really enjoyed
meeting Tom Osborne for that interview.  The link at the end is an
especially good read.

X < > Y,


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