Joe's HP 9855 Computer

Revised 10/19/2000

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The 9825, 9835 and 9845 Series.

Unlike the 9810, 9820 and 9830 series, the 9825, 9835 and 9845 were not all released at the same time. Also unlike the earlier series, the 98x5 series shared many common interfaces and peripherals.

HP 9845

AKA System 45. HP called the HP 9845 the flagship of the 9800 series. That's an appropriate term considering the size and weight of one! The 9845 A was introduced in the April 1978 issue of the HP Journal (picture). Their development code name was QWERT". The development code name for the 9845B was "Galleon". "There are four QWERTs in Galleon, you know". I swear that's what HP said! I asked how they came up with a name like QWERT and was told " My understanding is that the 9825 was called "keeper" which stood for key per function. This was the original design goal, however HPL turned into a pretty much full fledged programming language. Once a naming trend gets established, it tends to propagate. Apparently the 9845 team played on the keeper theme and adopted QWERT from the keyboard." The development code name for the color monitor used on the 9845C was "Odyssey". And finally the development code name for the 9845 option 200 was "Steamer". More on the option 200 later. The 9845s were available in a bewildering array of model numbers, options, packages, performance models and displays. The original model was the 9845A. It came standard with ~16k of read/write memory and one tape drive. In 1979 HP added the 9845S. The "S" model had 64k of read/write memory, two tape drives, a built in full page printer and a graphics capability. Both were replaced by the 9845B and 9845T 1980. The 9845C was introduced later the same year in the December 1980 issue of the HP Journal (picture). The "A" and "B" models could only display alpha text in twenty-four 80 character lines. The major change in the "S" and "T" model were that they had graphics capability with a 560 x 455 dot matrix screen. The "T" model also came standard with more memory (186k) , the optional full page printer and second tape drive. The reader should be aware that most 9845s are only marked "B" even though they may have the graphics capability. In addition, I have never found a 9845 that had the installed options or memory listed on it anywhere. The 9845C models had a color monitor with a 13 inch CRT that was capable of displaying 4,913 colors, vector writing and also had an interactive light pen. The light pen was made optional in 1983. All "C" models had the graphics capability. In 1983, HP also added a new high performance bit slice CPU as option 200. (All 2XX options include the new CPU.) The 9845s actually use two nearly identical CPUs. One was called the LPU (Language Processing Unit) and the other called the PPU (Peripheral Processing Unit). The LPU handles the BASIC interpreter and the PPU handles all of the system I/O. All of the HPL and BASIC language machines used interpreters and HP found that in most programs the machines spent 80% of their time in the interpreter. Therefore HP rewrote most of the BASIC language interpreter in microcode. I've been told that the microcode was 2K words deep and about 56 bits wide. HP also replaced the LPU with a bit slice processor. The bit sliced processor was composed of a single AMD2910 microsequencer and four AMD2901 four bit wide "RALU" slices. There was also a set of specialized BCD adders to handle the BCD arithmetic. Here is a description of the enhanced processor from one of the guys at HP that worked on it: "The option 200 processor was built completely with off the shelf circuits. A standard processor is a single board with a heatsink that looks like a motorcycle head. In fact the guy that designed it referred to it as exactly that. The option 200 processor fits in the same slot, but is actually a module composed of three primary PC boards, with an interconnect board on top. Since the base board in the bottom of the machine was called the motherboard, we naturally referred to the interconnect board as the father board." The new faster LPU coupled with the up to 1.6 megabytes of memory that was available in the 9845s made them very capable machines. They were widely used for CAD systems, micro-processor development systems, data base query systems. Unfortunately they were dropped from the HP catalog after 1984 in favor of HP's new 9000 500 series computers. That's not surprising however considering that the list price on a high performance color 9845C was $39,000 without any additional options, peripherals or software! However, at one time it was the leading revenue product for HP.

The 9845s were a wonder of micro-electronics. A fully optioned 9845A included 36 NMOS Large Scale Integration ICs, 19 Medium Scale Integration ICs and 75 NMOS ROM ICs. And the "A" was the bottom of the line 9845! All of the special ICs were custom designed and built by HP. The 9845C was much more complex. The color monitor alone contained four power supplies supplying 9 different voltages! The 9845s were third generation machines and featured all of advances of the 9825s and 9835s included the same live keyboard, high speed tape drive, an extended number range and all of the interfacing capability of the 9835s such as buffered I/O, DMA, fast read/write, 15 levels of priority interrupts and built in I/O drivers. A second tape drive and a built in full page thermal printer were optional. The 9845s still had the three I/O slots in the rear of the case but HP again changed the design of the option ROMs. This time they built slide out ROM drawers into both sides of the machine. They also changed the shape and size of the ROMs. They were now small printed circuit boards mounted in long plastic cases that plugged into sockets in the ROM drawers. Each drawer could hold eight ROMs. Many of the ROMs had to go into a specific drawer and slot. Therefore the left hand drawer was color coded green and the right hand drawer was color coded black and the slots were identified with symbols. The ROMs that had to go into a specific drawer or slot were color coded and marked with matching symbols. This brings up another tidbit, the 9845A housed ALL of its ROMs in the ROM drawers. However due to a manufacturing supply problem, the system ROMs were moved out of the drawers and inside the machine for the 9845B and subsequent machines.

Like the 9835s ,the 9845s could be programmed in BASIC or Assembly Language. However the BASIC was even more powerful than that used in the 9835s and was so well optimized that many routines were faster in BASIC than they were in assembly.

misc. The standard monochrome monitor is model number 98750A. The color graphics monitor is model number 98770A. There was also a monochrome Enhanced Graphics monitor with model number 98780A that included it's own CPU and a hardware vector generator.

9845 options

all 1xx options = standard LPU
all 2xx options = high performance LPU

Option 150 = ????
Option 250 = high performance LPU and ????
Option 190 = HP 98430A Data Base Management System ROM
Option 290 = high performance LPU and HP 98430A Data Base Management System ROM
Option 175 = standard LPU and data communications package
Option 275 = high performance LPU and data communications package
Option 280 = high performance LPU and HP's IMAGE database management package

Option (100 or 200) and 204 = 192k of read/write memory
Option (100 or 200) and 205 = 312k of read/write memory
Option (100 or 200) and 206 = 512k of read/write memory

Option (150, 190, 250 or 290) = 192k of read/write memory
Option (150, 190, 250 or 290) and 215 = 312k of read/write memory
Option (150, 190, 250 or 290) and 216 = 512k of read/write memory

Option (175, 275, 280) = 512k of read/write memory
Option (175, 275, 280) and 207 = 1,088k of read/write memory
Option (175, 275, 280) and 208 = 1,664k of read/write memory

Option 311 = HP 98411B Graphics ROM
Option 312 = HP 98412A I/O ROM
Option 313 = HP 98413C Mass Storage ROM
Option 314 = HP 98414A Advanced Programming ROM
Option 438 = HP 98438A Assembly Execution ROM
Option 439 = HP 98439A Assembly Execution and Development ROM

9845 ROMs

HP 98411B Graphics ROM
HP 98412A I/O ROM (set of 2 ROMs)
HP 98413C Mass Storage ROM
HP 98417A Basic Data Comm ROM
HP 98414A Advanced Programming ROM
HP 98415A Structured Programming ROM
HP 98417A Basic DataComm ROM
HP 98418A Bisync DataComm ROM
HP 98438A Assembly Execution ROM
HP 98439A Assembly Execution and Development ROM
HP 98430A Data Base Management System ROM


(1979) 9845A = $11,000
9845S = $20,000
(1981) 9845B = $14,000
9845T = $23,500
9845C = $39,500
(1983) 9845B with option 175 = $24,000
9845B with option 275 or 280 = $28,000
9845C with option 275 or 280 = $39,000

Size and Weight:

Base (w,d,h) 27 x 19 x 10 inches 45 pounds
HP 98750A Monochrome monitor 13 x 13 x 10 inches 23 pounds
HP98770A, Color CRT 18 x 17x 15 inches. est > 50 pounds

Click here for a list of HP 9845 interfaces.

AND finally here I am still hard at work!

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