It's not necessarily better, although it does what I happen to want better. I actually ordered a set of your boards too and built one.
There are a whole list of intersecting preferences that cancel each other out, and some are just things I want and I don't care who else thinks they are of any value. Each one by itself has some other alternative answer, but that other answer comes with some other issue, and so on. For instance an easy one, Being able to re-program without de-soldering is valuable of course. Being able to re-program without either a dip28 test clip or a custom dedicated purpose adapter is also valuable. It's not that these are impossible burdens, but less and simpler is better. So ideally it would be good to be able to remove the new standard eprom to reprogram it. So that means a socket for the new eprom. Then again, it's ALSO true that having the option to put the original mask rom back in (not merely reflashing an image that purports to be the same) is also valuable. Especially when it's 15 years from now and the eeprom is losing bits and you just got this thing and don't know what these wierd hacks are some previous owner did. Also for reference, like when I was trying to figure out why pg designs menu.ba was not working yesterday. So that means a socket on the motherboard. There's no way there's room for two sockets and an adapter and a chip between the motherboard and the keyboard. But if you say you normally plug your adapter into the original socket on the motherboard, then that proves there is room for one socket. You're right that a programming adapter would be pretty easy. Except I also would prefer to use eeprom instead of uv, which your board is not configured to use, and, it would also require adding a pullup and a jumper header to your board to handle WE or else you couldn't actually program with just an adapter, you'd need a test clip. That's all doable and everything would fit the same, but that's not what your board actually is. (Actually, I like the option to use either uv eprom or eeprom, in case one or the other lasts more years before losing charge.) And I also would like, if possible, eventually, to be able to just buy the same part for both main and option rom. Or rather I'd like to work out that recipe for the future. I myself have already bought all kinds of stuff already for just 3 machines, so working out the most efficient recipe doesn't reduce anything for me, but it's still good to do. So, if there was a 28C256 dip28 in the main rom, then could we get a 28C256 dip28 on an adapter in the option rom? Actually yes. I have old commercial option roms which are cerdip28 squeezed onto an adapter pcb. You might even just barely manage to get a pullup resistor and jumper header on there for write enable. Though I am finding out the hard way that a programming adapter to grab those half-hole edge contacts is not so easy to make. Far far better to either remove the eeprom, or use a test clip Well there is no room for a dip socket for the option rom so that just leaves a test clip. Why make people buy a test clip if there is a way without it? As for the option to load an option rom on the same chip as the main rom and bury it inside the case, and render the option rom socket unusable; That option is interesting and cool in the abstract, but nothing I would want to do. I want to be able to snap in actual old roms, and play with loading different ones from images, and eventually maybe even hack on them. Sorry; how is this any better than the M100ROM on Bitchin100? You have to remove each M100s main board and unsolder the ROM socket? Aside from any considerations of 'keeping it original' that's not everyone's cup of tea, but if you really want to do that then of course you can do it with the M100ROM as well. On the other hand, the M100ROM is normally a plug-in solution not requiring any mods to the M100 at all; if you really need to reprogram the chip, an adapter is pretty simple, would probably not take much longer to make than unsoldering the M100's socket, and would work for as many (unmodified) M100s as you like. You want to use an EEPROM? DIP 27C256s are dirt cheap and thick on the ground but I don't see why a compatible DIP EEPROM would be a problem. And of course the M100ROM gives you the option of adding TS-DOS or any option ROM of your choice while you're at it for essentially the same cost and assembly time. But to each his/her own I guess; maybe I'm a little biased but personally I'd rather spend 15 minutes or so making a one-time programming adapter (if I in fact ever need one) than removing the main boards in all my M100s and unsoldering and replacing the main ROM sockets... m ----- Original Message ----- *From:* Brian White <[email protected]> *To:* Model 100 Discussion <[email protected]> *Sent:* Wednesday, June 01, 2016 10:45 PM *Subject:* Re: [M100] Main rom using 28C256 plcc How many times do I have to write plcc in one mail? :) Physically it's all identical to the previous 27C256 plcc version. I am currently using the 27C256 version in 2 M100's already, so the physical fit is tested. Just to be clear, it requires desoldering the original dip socket and putting this adapter in it's place. And the adapter has a plcc socket on it. So in the end you have a socketed standard 28C256 instead of a socketed non-standard LH535618. And you can re-program the eprom without any special adapters or a test-clip, because the eprom itself comes out by itself. It's only for the early model 100's of course. Later ones you just use a 27C256 DIP with no adapter. -- bkw On Jun 1, 2016 10:10 PM, "Stephen Adolph" <[email protected]> wrote: > Nice find. Ebay source or retail? > Let us know if there is just enough space. Is the 28c256 a dil package? Or > soic? > > On Wednesday, June 1, 2016, Brian White <[email protected]> wrote: > > https://oshpark.com/shared_projects/bCqiBZLI > > > > This same guy had a 27C256 version, but erasable 27C256 lcc are really > hard to find. You can buy OTP parts new, but not erasable. > > > > So he made a 28C256 version. You can still buy new 28C256 plcc. > > > > Maintaining a socket of some form is more important than I realised at > first because I wasn't aware that eproms and eeproms might lose bits in as > little as 10 years. So an eprom/eeprom absolutely will need to be > re-flashed again sometime. > > > > I found these low profile round pin headers to use with it. You need > both qualities, round pins and close spacing between the motherboard and > the module. > > http://www.king-cart.com/phoenixent/product_name=HWS5231 > > > > Untested yet. I'm ordering now. > > > > -- > > bkw
