Hi Frank; you must be on just about every vintage computer list out there ;-)
Any chance you'd release the PCB files for those boards to the unwashed public? mike ----- Original Message ----- From: "Francesco Messineo" <[email protected]> To: <[email protected]> Sent: Thursday, July 06, 2017 3:13 AM Subject: Re: [M100] NEC 8201A Ram > Hello, > I'm new to this list, I've been just reading for a while. > > On Thu, Jul 6, 2017 at 6:14 AM, Brian White <[email protected]> wrote: >> 102 is easy. 100 is not so easy. >> >> There was a guy in Romania selling NEC branded modules dirt cheap last year >> but those are gone now. Or at least they're not on ebay any more. They >> weren't labeled for model-100, I just found them by searching for the main >> chip number, took a chance, and they turned out to not only fit but also >> work. Maybe I should save his info before I lose track of it, in case he >> does still have some. >> >> Maybe modules for 100 are another good candidate for an open OSH Park design >> that people can build new on-demand. The basic wiring for adapting to some >> more common chips is well documented. >> > > I've made many RAM modules replacement for the Olivetti M10 (and all > the other compatibles) for some friends that asked for batches of > them. > Here's how one module looks like inside my M10: > > https://www.dropbox.com/s/iwyjg7p22c8xt5t/IMG_1484.JPG?dl=0 > > I've developed also a custom setup to test the modules outside the M10 > (socket was getting > worn out during my prototype tests): > > https://www.dropbox.com/s/38q01n8gckuz3of/IMG_1906.JPG?dl=0 > > And here's one of the batches I've made for an italian collector: > > https://www.dropbox.com/s/c5zes6lgevdkz2n/IMG_0266.JPG?dl=0 > > And here's another version of the module with slightly different logic > to use different SRAM > chips: > > https://www.dropbox.com/s/1p9tz1jgirbfaee/IMG_1601.JPG?dl=0 > > The test setup include different address and block tests and also a > standby current measurement as these modules must not draw more than > 2-4 uA during standby conditions to allow the memory battery backup > last a reasonable amount of time. > Most of the modules settle to much less than 1 uA standby current. A > few ones went up to 1 uA. The original modules can draw up to 4 uA in > standby mode. > > Best regards > Frank IZ8DWF > >> -- >> bkw >> >> On Jul 5, 2017 10:29 AM, "Jason Benson" <[email protected]> wrote: >>> >>> I want to fix the 8201A but I haven't had any luck yet determining the >>> cause of the trouble. (see other thread about internal NiCd batteries) >>> >>> On Wed, Jul 5, 2017 at 10:05 AM, Josh Malone <[email protected]> >>> wrote: >>>> >>>> What happened to the 8201A? It might be more beneficial to just repair >>>> that. >>>> >>>> I can tell you from experience that SRAMs for the model-T are easy to >>>> come by. (I recently replaced a RAM chip in my 102 w/ parts from ebay) No >>>> reason to scavenge other machines for these parts. >>>> >>>> -Josh >>>> >>>> On Wed, Jul 5, 2017 at 9:19 AM, Jason Benson <[email protected]> >>>> wrote: >>>>> >>>>> My 8201A that died the first time I tried to use it has a full set of >>>>> ram expansions. Are those ram expansions usable in any of the other >>>>> computers from the M100 family? I imagine the NEC PC 8300 probably uses >>>>> the >>>>> same chips, but probably not the M100/102. >>>>> -Jason >>>> >>>> >>> >>
