PROMS.THD --- Copyright 1987 by Phil Wheeler An original compilation of Compuserve Model 100 Forum messages for use by Forum members only. Vendors have been selling Model 100/102/200 software on ROM chips for some time, even in custom ROMs in some cases. This file captures the latest series (actually, two series) of messages on "doing it yourself" -- with both hardware and software issues touched upon. Message range: 149516 to 149813 Dates: 6/6/87 to 6/10/87 Sb: #EPROM in ROM Socket Fm: Stan Wong 70346,1267 To: All I would like to put some of my commonly used programs and files into a standard EPROM and plug it into the ROM socket. Is there some sort of adapter that is commercially available or that someone has built? I have access to a PROM programmer so creating the PROM is no problem; how to interface it is. The pinout of the M100 ROM socket doesn't resemble any of the EPROM pinouts I can find. Any help would be very much appreciated. Fm: Tony Anderson 76703,4062 To: Stan Wong 70346,1267 Wouldn't we all... But lacking the technical expertise, or the equipment to find out what's what, no one has yet come up with how to do it, and placed the information in the public domain so that anyone else could do it. Oh, a few people have figured out how to do it... and have based commercial businesses on the technique. They charge about $500 for burning ONE EPROM, and generously drop the price to around $50 each for a dozen or more... A move designed to eliminate the individual user, and favor the large commercial market. As you noted, you need some sort of adapter to unscramble and reroute the address lines, for use with standard EPROM's. None are available. They are custom made for the companies who do EPROM burning, and to the best of my knowledge, are not available for sale. There is one company who can burn an EPROM for about $60, but they have not developed the technique of running the programs from the ROM... it's used strictly as a storage bank, and programs are "loaded" into regular RAM to be run. -- You might as well get an extra RAM bank; at least you can make changes in programs as needed... or get a disk drive... one disk holds the equivalent of 6 EPROMS or RAM banks, and an entire bank of data can be loaded or saved with a single command. With such functional disk drives around, the days where the Optional ROM for personal use may well have passed. I can see where it still has a useful market in the commercial area, especially with dedicated programs used by a large number of people in a company. But for most of us, the disk is simply a better choice. Fm: Ran Talbott 70506,60 To: Tony Anderson 76703,4062 _Would_ we all want to use EPROMs? There's nothing that magical about it. The adapter is not that hard to make, though it would be a bit tricky to assemble and use. Personally, I would be more inclined to build a board that would plug into the system bus, like the RAM bank whose manufacturer escapes me. It would make it easier to change the EPROM (I think it would also require the use of skinny-DIPs that I've only seen in photos). The big question is how to make use of the ROM: as you pointed out, it takes some special programming to use it as anything other than a "disk". I wonder how many people (other than developers of products!) would really do it. There are good reasons for using ROMs: portabilty and operational simplicity come to mind. Not to mention the fact that I occasionally get the perverse desire to punch a button and turn the M100 into a FORTH machine. I do wonder how much company I've got, though. Fm: Tony Anderson 76703,4062 To: Ran Talbott 70506,60 I for one am not impressed by the magic of ROM technology. But in many applications, I can see it's usefullness... particularly as I mentioned, where a company has equipped a number of it's employees with 100's, and they all need to use the same program. Aside from that, seems like a disk system makes so much more sense. Fm: Stan Wong 70346,1267 To: Tony Anderson 76703,4062 I wouldn't mind having just a storage capability with an EPROM. I could get a disk but the whole aim is to keep size and weight down. A disk drive would add quite a bit of both. The reason for the EPROM is so that I can reprogram it as programs change. If I can figure out what the chip select (CS) pin does then I might have a chance. I guess I'll consult some of the hardware folks at work. If I do eventually wind up with something that works you can be sure that I'll publish it here. In the meantime, any other help I can get will be appreciated. Fm: Ran Talbott 70506,60 To: Stan Wong 70346,1267 The CS pin in the ROM socket is controlled by a latched output pin: in one state it selects the internal ROM, in the other it selects the option ROM. The trick to using an EPROM for storage is to write an assembler routine that sits in RAM and switches the ROMs. It can copy data from the EPROM into RAM. Fm: Tony Anderson 76703,4062 To: ALL New file in DL8 (LINES.EPR) lists the pin connections for the adapter to use standard EPROM's in the Model 100 family's optional ROM socket. Based on a visual examination of a commercial ROM, and may not be entirely accurate. But it's a starting point... Fm: C. Davey Utter 70055,522 To: Stan Wong 70346,1267 There is, and you can get one from John Ross 76703,551. Email him and he will send it to you, don't know what he sells them for but it ain't much, let me kow how you make out, I'm interested in doing it too...Dave -------------------- Sb: #user prom's Fm: Mark A. Fleming 73336,3444 To: sysop I was wondering if there was any info on the format of plug in romware. Would it be possible to create a prom program which will appear on the main menu when my prom is plugged in? Since I have access to a prom burner, I thought it would be nice to put a few programs permanently on the menu. If you know of any upload files, messages, or books on the subject, please drop me a line. Thanks. Fm: Denny Thomas 76701,40 To: Mark A. Fleming 73336,3444 So far none of that information has appeared in the public domain. Companies that have the info have based their business on it. Fm: Tony Anderson 76703,4062 To: Mark A. Fleming 73336,3444 You can check LINES.EPR in DL8, as my meager contribution to understanding the EPROM situation. Fm: Ran Talbott 70506,60 To: Mark A. Fleming 73336,3444 I don't think it's possible to make it happen _automatically_, but the trick is to write some simple .CO files that toggle the ROM select bit and CALL the real program in your EPROM. You'll also need some sort of interface code for communicating between your EPROM and the subroutines you need in the ROM. Ran PS - It occurs to me you might not have discovered yet that the plug-in ROM occupies the same lower 32K of address space as the built-in ROM, and they're "bank-switched".