It must be possible to read out the ROMs without opening the mosdule, after all ,thats; what hte HP9800 does when it runs said programs. In fact, the only signal you can find internally and not on the moduel conencotr is the -V Vbb bias supply (there's a -12V rail on the conenctor and a potential divider ins the mdoule). The module, as I am sure you're aware is just 4 of those HP512*8 ROMs and the potential divider. Such a program would ahve to be in machien code, and there's no way to enter machien code o nteh keyboard on any of these machines. I guess he's got something on tape or cards to do it. Eitehr that, or he grabs the data from the M and T registers when the machine does the power-on memory scan. I will contact Achim (do you have his address? it's remarkably hard to find), but I don;t hold out much hope. I suspect he'd like all the ROM images for his HP9800e emulator (said package includes PC1 for the HP9820 and DataComm 1 foe the HP9830) and I would have thought he'd already asked the Australian Museum. Incidentally, if you want to know what I want it for, no I am not running an emualtor. Or writing an emualtor. Take a look at the talks on the Sunday of the HPCC conference this year :-) -tony

Making an EPROM module fo rthe HP9800s is one of htose things htat looks quite easy on paper -- the only oddity is the enable signal -- but spriisngly hard when you come ot do it. Particualrly in the HP9810/20, where the ROM moduel backpalen is wired up on a horrble bundle of wires which have signficatnt inductance. Decoupling well is essential, even then it;s not as easy as it looks... Put it is worththe effort. I noww have DataComm 1 for the HP9830, so I cna finally make use fo the 11284 interface I have. I have C1 nd PC2 for the HP(810, so I can get that machine talking to a serial port, etc. Alas PC1 for the HP9820 doesn't allow the sort of low-level access I'd like, which is why I'd like PC2... -tony

Given how hard it is to find the original ROM modules, I am not suprised :-) I thought about doing soemthing like that, but there are problems. The first is that so far I have found : 8 ROM modules for the HP9810 4 for the HP9820 11 for the HP9830. I know of at least one more for the 9820 (PC2) and 7 more for the 9830 (DataComm 2, DataComm 3, and the 5 FastBASIC modules). Now, the 9810 nad 9820 have 3 slots for ROM modules, the 9830 has 8. The number of slots is effectlive 'hardwired' int othe memory map of the machine. So there's no way you could ahev lal the ROMs availalbe at onxe. You would need to hev some way of selecting which ROM you wanted in each slot. Then there is the problem that the singals on the ROM module connector ocnsit of : Power lines, the 9 low-order address liens (A0 to A8, and also A8/), the 16 data lines, a precharge line (CE) and 2 selects (for the 2 sets of ROMs in a real HP module). You don't have access to the highter order address liens or more module sleects. So a multiple ROM odule would involve modifcations to the machine. For the 9810 and 9820, it could conenct to tyhe card edge on the main backplane in palce of the cable to the ROM backplane. For the 9830, I think it would be sinplest ot replace the EXT ROM Selector board in the machine (this has the higher address lines on its conencotr) and also one of the itnernal expansion ROM boards. The 2 replacement board would have ot be linked by an over-the-top cable. In both cases there are rater more modifications to the machien that I would like. You also can't use real HP moduls at the same time. And the ROM sleection logic in a little complex. Not ridiculously so, but I try to use the sort of deices that were avaialbel when the machien was in use, so I would not want to use programmable logic here. It's out of character. So what I did was make a board that acts as one module. It plugs into the module conector with no changes to the machine. You cna put HP modules in thew other connectors if you want to. The board cotnaisn a pair of EPROMs (2764/27128/27256). It's a lot simplere to use 2 EPROms to get the 16 bit word than to have logic to extract the word from 2 locations and latch it. My programmer doesn't ahndle the more modern 16 bit wide EPROMs, so those were 'out'. THere's a few passives, a couple of transsitors to bring the 12V sleect lines back down to 5V, and a simple TTL chip to cenerate the ROM CS/ signal. There's one board for the 9810/20 (same modules, electrically), another for the 9830. They are both hand-wired at the moment, I intend to design a PCB version sometime. Each 1K of EPROM will hold a moduel image. So if you use 27128s, you can store either all the 9810 _and_ 9820 iamges, or all the 9830 images. There's a DIP switch on the board to select which image you want. Maybe not elegant, but simple. Some gotcha's... Decoupling is very important, particularly on the 9810/9820. You need 1k pullups on the address inputs and, for some reason, on the output of the TTL logic feedign thr ROM CS/ signal. You need to use one of the level-shifted moduel chip select signals to provide the A9 signal to the EPROM so that the 2 halves of the module map to different parts of the EPROM. The address and dat aliens at hte moduel conencotr are active low (FWIW, the M and T registers in the 9800 machines are active high, but there are invertes on the address and data lins to the module, look at the schematics). This is no proble, oyu jsut flip bits around when you make the image to program into the EPROM. I don't suppose you're coming to the HPCC conference next month [1]. I am presentign the module there. If not, I will get scheamtics to you somehow. If there's ever a PCB version, I'll let you knwo about that too. [1] Anyone here is very welcome to come along, It's 27/28 October 2012 at Imperail College, London (England) Thsi is not really a classic computer event, but there's a talk each day on classic HP desktop machines [2], and many of the members have interests in old computers, calculators and other related thigns. If you want to come, please let one of the HPCC committee know. [2] It is pointles to argue whether or not these machines are classic comptuers or not. Many of them are comoters intenrally (processor addressing memory + peripherals),. They are user-programamble. OK, they are designed for calcualtions rather than, say, text processing, but that comment could apply to someting like a KIM 1. They were not called `computers' by the manufacturer, but that also applies to PDPs. If they're not something that itnerest you, fine. -tony