The hp85 was the answer from HP to the first personal computers. As such, it predates by two years the IBM PC; but it had been designed and produced by the calculator division in Corvallis, Oregon.
Completely different from the computers that were designed at that time by the likes of apple and others, this one was built around a calculator CPU, optimized for BCD calculations; and it had several attributes that we now associate with calculators, not computers.
For one, it had a ROM of 48kb, something unheard of at the moment; all the operating system and the basic interpreter were embedded in that ROM; boot up was instantaneous. It took longer for the white-phosphor CRT to warm up than for the cursor to appear on screen. The “knowledge” of the calculator could be increased by ROMs that could be loaded in a ROM cartridge, to be connected in the general computer bus. There were at least a dozen of them, covering many areas, from advanced programming to matrix, and from plotter/printer to voice generation. (Note: I am looking for the voice generator ROM. I have even seen it in the eighties, but never more, and I have not seen it in Ebay yet. Please drop me a line if you know where to find it)
the initial models (”A” to distinguish it from the late “B”) had only 16kb. If I remember well, it could be upgraded up to 64 kb via memory modules for the above bus system. This is the model I have, upgrade to 32 kb.
The screen had 16 lines of 32 characters; and the pixel resolution of the screen was 256x192. It could be scrolled down, for a much as 64 lines (equivalent to 4 full screens)
It came with mass storage (a 256kb tape) and a thermal printer (that had exactly the size and aspect of…well, you know what.) If you wanted a floppy disc, you had to have it external. Typical units had 2 5¼ floppy discs, and you would have the program in one of them and the data in the other. The drives were an HP-iB device, and therefore you had to set an address for them, using the switches at the back of the machines. Talk about usb self-configuring devices…
The hp-ib was the interface of choice. Hp-il and rs–232 were available options, but most users had the former. I remember having a hp85 configured with a twin floppy drive, a dot-matrix printer, and a plotter. Hp-ib hadled perfectly the complexity, and you could copy data from the disk and plot it with the flatbed 7225a plotter. All in the office stopped: seeing the plotter do its job was something to behold.
The tape was exceedingly slow, but I could not help but compare the quality of the assembly with the then ubiquitous cassette units, used by the Sinclair ZX–81 and Spectrum. It could handle directories, but the names of the files were limited to 6 characters (I remember thinking “whoah! 8 characters in MSDOS: this brings a lot of possibilities”).
The keyboard was excellent for the time. For current users, the keys have too much displacement, and are hard to press, compared with current laptops; but numbers were not printed on the keys, but co-extruded with the key instead.
We have a unit on offer, in pristine state, with its carrying case, HPiB interface, two tapes with programs, and with a new tape drive and printer rubber chains. You can find it here