WTT: HP 85 Assembler ROM 00085-15007

[rprosperi]

(02-05-2016 10:10 AM)Michael Fehlhammer Wrote:  I wonder why only 7 of 8 ROM images can be used in the PRM-87 that officially is for sale now?

The default 5 ROMs for the 87 SuperROM match those of the 85 core set. The APR-2, Matrix-2 and Plotter ROM are "extra" and one can enable any 2 of these 3 via the 2 Dip Switches and jumpers. The "limit" is simply due to the fact that there are only 2 Dip switches.

I've just learned though that in order to use the APROM or Matrix ROM, you need both ROMs 1&2 enabled. Though I've read in various places that the 87 versions have more functions, it appears the 87 versions of these ROMs are just about the same as the 85 versions, but the code size for the 87 version (perhaps due to the different addressing?) exceeded the 8KB in the originals, so they "overflowed" into a 2nd ROM.

(02-05-2016 01:10 PM)Paul Berger (Canada) Wrote:  It would seem that the cards are being distributed with the preprogrammed select codes in the PLD aimed at 85 users, and the "SuperROM" provided does not match up with three of these codes, in fact only one of them is much use to 86/87 users and that is the service ROM, which is not in the received "SuperROM" image. The select code for the Mass Storage ROM is of little use as the mass storage ROM is built into 86/87 systems, and there is no 86/87 equivalent to the Program Development ROM. So the only option is to use the switches to enable 2 of the 3 images, which degrades the usefulness of the card. I am guessing that you "Custom PRM-87" has a custom programmed CPLD with a different set of preprogrammed select codes, if that is the case it would make me wonder why the seller does not make that available as an option to current buyers. I also don't understand why the service ROM would be part of the default set, it would seem to me that it would be an infrequently used ROM and could be burned into a single image ROM and installed in the second socket when needed.

Indeed the MS ROM, PD ROM and Svc ROM (defaults in the 85 flavor) do not apply to the 87, hence the other 3 "extras" are available via user-selected ROM IDs.

It's not perfect, bur for those of us mere mortals that cannot design and build out own ROM boards, it is a great solution that works. I'm happy to be able to have the features of these ROMs without spending a fortune and years searching.

I'm also glad to know from Michael's notes that more than 1 ROM image could be installed in an EPROM in the available slot. The 2 custom System Extension ROMs on Everett Kaser's site look very useful, and if both can be added in an EPROM, it means I would not have to choose which one is best.