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HP Series 80
The Series 80 Personal Computer product line was introduced by Hewlett-Packard in
1980 with the HP-85 model which was one of the earliest integral desktop computers
that in the same cabinet included the main computer, a printer and a tape drive.
Over the product line life span HP developed several models. The early and original
HP-85 with 16KByte RAM and 32KByte System ROM was known as the HP-85A and was
introduced in January 1980.
At that time I was already doing programming in BASIC and APL on
IBM 5100 and
IBM 5110 computers,
they had almost the same form factor as the HP-85, small CRT screen on the left,
tape unit on the right and a full size keyboard and ROM resident BASIC interpreter.
The IBM computers had a decent version of BASIC for financial and office type
applications, one of my early projects consisted in developing a payroll system
to manage payroll for the teachers in my school. But the IBM stuff was pretty
expensive and heavy, nothing that you can consider close to "portable",
but the HP-85 was my favorite, much nicer design, cheaper and more oriented for
engineering and scientific applications.
At some time the HP-85 was the preferred choice as a controller for automated
measurements, I still use one in
my lab to control a bunch of HP-IB capable instruments.
One interesting characteristic of the HP Series 80 was that its architecture was
not based on any of the available microprocessors at that time, instead HP developed a
set of specific custom large scale integrated (LSI) circuits for the HP-85 which
let them reduce the number of external components and power dissipation enabling
the use of air convection instead of the noisy fans for cooling.
Even for an 8-bit CPU (code name "Capricorn") running at a 614KHz the
performance was very good, since the CPU was designed to use a multiplexed
data/address bus optimized for multibyte transfers (frequently used by BASIC
interpreter tokens and numeric values) and minimizing the need to constantly send
addressing information for each read/write operation.
There are many publications and great sites available today with plenty of
information about the HP-85 and the rest of the HP Series 80 family. There is a list of
links at the bottom if this page.
Also the entire
July 1980
issue of the HP Journal was dedicated to the HP-85 and in the
August 1980
issue you can also find an article from Todd Lynch about the LSI chips
used in the HP-85, and courtesy of Eric Smith a copy of the
patent application
that Todd Lynch/HP filed for the Capricorn CPU.
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HP-85A Personal Computer
HP-85A "Naked"
HP-87XM Personal Computer
HP-86 Personal Computer
[Click Images to Enlarge]
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HP Series 80 Projects
As I mentioned before, the HP-85 was one of my favorite machines, and there are
many that are still in use and in good operating condition, but some of the
accessories are very hard to find. For example I don't have some of the original
expansion ROMs such as Assembler, Mass Storage, etc. I've been looking around
for a while for a HP 82929A Programmable ROM Drawer and use some
EPROMs with the images of the missing ROMs, but with no luck yet.
On the other hand over the past few years I've been doing microcontroller based
designs, then I decided to start some projects to get more juice (lets be
frank, and also for fun) from the HP-85 and emulate some expansion modules
and external interfaces using microcontrollers (if you know well the HP-85 architecture
you must know that most of the external interfaces had an Intel 8049 microcontroller
doing the job).
My first project on the list was to find/obtain/steal/replicate/materialize a HP 82929A
Programmable ROM Drawer. I know that some folks have done it in the past but
I didn't find much information available on-line.
Some time ago Bill Kotaska with support from John Shadbolt developed the
PRM-85
as a replacement board for the HP 82929A. I tried to contact Bill but with no luck,
but John was fast to reply to my request for information, without his help
this first project would have been almost impossible to complete.
I also need to mention Everett Kaser who while at HTP was involved somehow in the HP-85
development and is the author of one of the HP-85 emulators for Windows and
provided great information a lot of insight and encouragement, Tony Duell
that if you you have been reading some forums/mailing lists about
classic computing or
retro computing you probably know that he has always something to say and
interesting information to share, and Vassilis Prevelakis and the HP Computer
Museum folks for making such a vast collection of manuals and information
available on-line.
Through these pages I intend to share the information, and status of various
HP Series 80 related projects I'll be doing as my time permits.
Enjoy !!!
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Useful links
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