HP "calculators" (was Re: World's first computer on ebay!)

I can't identify it exactly, but I am pretty sure it's one of 2 machines, one rarer than the other. The more common one is the HP9820. The rarer one is the HP9821. They're much the same to program, the difference is that the 9820 has a magnetic card reader at the rear right of the kayboard, the 9821 has a digital cassette drive (takes tapes that look like audio compact cassettes) there. They're members of the same family as the 9830 that I mentioned as a contender for the title of 'first personal computer'. There's one other model in the family, the HP9810, which is a 3-level stack RPN calculator, similar to the HP9100 to use (although totally different internally). They're all really computers in that they have a central processor linked to RAM and ROM, with the keyboard, display, printer,etc as peripherals. The processor is 16 bit, bit-serial, with 2 accummulators (A and B), program counter (P), 'Wualifer' (instruction register) Q, Memory address register (M), Memory data register (T), Extension register (E, only 4 bits wide) and an I/O register. The processor is built on 4 PCBs (these boards are common to all 4 machines in the family), containing about 80 TTL ICs. It's microcoded (there are 7 ROMs on on of the PCBs containing 256 28-bit words). The ALU, strangely, is a pair of ROMs on another of the boards contianing look-up tables for the functions. The M and T registers are not on the processor boards, they're on memory interface boards which are different in the various machines. The 9820 has 1 or 2 1K-word RAM boards (using Intel 1103 DRAMs) and 2 ROM boards each contianing 2K words of code. 3 optional ROM modules (1K words each) can be plugged into sockets just behind the display. The dispaly is 16 characters, dot matrix, and is driven by the firmware. The keyboard, on the other hand, is encoded in hardware. It's an odd design of keyboard, in that there are balanced teansformers formed by spiral PCB tracks under each key. Pressing a key brigns a piece of metal over one of the 'windings', unbalancing the system and providint an output pulse that's detected by the encoder electronics. It's reliable, but I guess rather expensive. Coincidentally, I've got a 9820 in bits on my bench at the moment. I bought it on E-bay, described as a 'non-working HP9820', and that's what it was. I'll emphasisse here that I have no complaints against the seller, he sold me just what I expected. Anyway, I've cured the electronic fault (a defective shift register chip in the M register circuit). There are 3 other faults. One is that an edge connector has been removed from the I/O backplane (and removed very well, I might add, there is no damage at all to the PCB tracks). I can get one card reader roller and printer platten have turned to goo. And the card reader spindle buckled and shattered when I tried to get the roller off with a puller. My poor little cat, who often watches me repair classic computers, was rather scared by this :-( (What is it about cats and classic computer enthusiasts???). Anyway, I've got to make a new spindle, and then work out a way to repair the platten. Still, it should be possible... Getting back to der Mouse's memories, the strip printer was built into the machine, but was technically an option (I've yet to se a 9820, or a 9810, which took the same optional printer, without it). The larger external printer may well have been an HP9866 (the 9866A is upper case only, the 9866B is mixed case). The plotter was probably an HP9862. There were several standard interfaces available, including 8 bit parallel 'GPIO' (used for, amongst other things, paper tape punches and readers0, a BCD interface (to read in readings from digital measuring instruments), an RS232 interface, etc. There was also an HPIB interface (I think this was the first ever family of mahcines to have HPIB). For the 9830 (the top model in the range, running BASIC), there was a complex and powerful asynchronous _and_ synchronous serial interface. You can get some manuals, including prgoramming info and boardswapper guides from http://www.hpmuseum,net/ The language developed into HPL (offiically 'High Performance Language', but it's obvious what it really stood for) which was used on the 9825 (manuals on the same site). On the 9820 it was a key-per-function language with a key for 'PRT', etc. The R() array, of course, stood for 'registers' The main differece to BASIC is hos you write an asignment. Rather than C=A+B, you write A+B->C (wehre -> is a right-arrow, called 'Gozinta' in some technical docs I've seen) You may have gatehrered I rather like this family of machines..... -tony