On Thu, Mar 15, 2018 at 7:57 PM, Mike Stein <[email protected]> wrote: > Hi Frank, > > How about we split the difference and settle on .73"? Try putting a 16-pin > DIP (which should be .700" end to end) into a RAM module socket sideways and > I think you'll find that it's a little too short; if you use .1" perfboard > you'll have to bend the pins a bit.
Well, I don't know, my 700 mils modules work well, I think the difference is so relevant. > > In any case, the socket spacing is at least .100" wider than the RAM chip. > > As to using diodes, I've often used this technique but I must confess that I > never measured the standby current. But I don't quite see why that should > keep it out of the standby region; with a pull-up resistor and no selects > pulling down the diodes /CE should be at Vcc. I think it can be done, but you anyway need logic to reconstruct the addresses, so why bother with diodes? I use only one logic chip for all the work. > > Also, at least one of the commercial modules used diodes, so perhaps it > depends on the RAM chip; some experimentation might be in order. > > m > > > > ----- Original Message ----- > From: "Francesco Messineo" <[email protected]> > To: <[email protected]> > Sent: Thursday, March 15, 2018 1:27 PM > Subject: Re: [M100] 8K RAM Chip > > > On Thu, Mar 15, 2018 at 6:08 PM, Mike Stein <[email protected]> wrote: >> Yeah, there are a number of ways to deal with the non-standard RAM modules >> in an M100; the pin spacing of the modules is .75 instead of the standard >> .60, so you will probably have to make a little adapter board in any case. >> > spacing is actually 700 mils > >> A self-contained module has to combine the four discrete chip selects into >> one, and also re-encode them into the binary upper two addresses. There are >> various ways of doing that and I have some of the commercial circuits >> somewhere but can't find them at the moment. >> >> One way would be a priority encoder as Fugu suggests. His 32K idea is clever >> and you could just used diodes to combine the chip selects; as a matter of >> fact you can also use an 8K chip and use diodes for the encoding instead of >> the encoder IC. > > A word of warning about using diodes to combine the selects: all the > low power cmos rams need close to Vdd or Vss levels on the select to > have the lowest current consumption when in sleep mode (Vdd circa 3V > inside the M100). > If the ram chip doesn't go in the correct standby mode, the internal > battery of the M100 is drained in about one day instead of the usual > one month (tests done in my Olivetti M10 several times). > > > Frank >> >> ----- Original Message ----- >> From: Fugu ME100 >> To: [email protected] >> Sent: Wednesday, March 14, 2018 5:14 PM >> Subject: Re: [M100] 8K RAM Chip >> >> If you did not want to use the Libero method you could use a 74HC148 (or >> similar) 8 to 3 line priority decoder and put the 4 CSx- lines into the >> upper or lower 4 inputs of the ‘148. That would recreate 2 address lines and >> a new CS- for the 8Kx8 SRAM. It could all mount on a proto-board and not >> require any 'soldering to' the M100 :) I would guess the NEC board uses a >> similar method but with an HC149 8-to-8 line priority encoder. >> >> Alternatively use a 32Kx8 SRAM and waste 3/4 of the space, but it would >> still need the CSx- lines ANDed to generate the SRAM CS-. Again no soldering >> on the M100 required. >> >> >> >> From: M100 <[email protected]> on behalf of Mike Stein >> <[email protected]> >> Reply-To: <[email protected]> >> Date: Wednesday, March 14, 2018 at 12:19 PM >> To: <[email protected]> >> Subject: Re: [M100] 8K RAM Chip >> >> It needs more than just remapping the signals; the required upper two >> address lines are not available on the sockets so you either need to add >> logic to recreate them or modify the main board. >> >> m >> >> ----- Original Message ----- >> From: Gregory McGill >> To: [email protected] >> Sent: Wednesday, March 14, 2018 1:22 PM >> Subject: Re: [M100] 8K RAM Chip >> >> thanks! It seems like we should be able to use the 8x8 chip from the 102 >> with some kludging of lines.. they are pretty close.. >> >> Greg >> >> On Wed, Mar 14, 2018 at 10:08 AM, Brian White <[email protected]> wrote: >>> >>> There are at least a few different "build your own ram upgrade" articles >>> on club100 and other archives of old forum posts, and in magazines too I >>> think but those are hard to search. >>> >>> Here's one that is not one of the old original ones I was thinking of, but >>> looks ok. >>> >>> http://digilander.libero.it/rar2k/TRS80/Memory24k.html >>> >>> I have some NEC modules that work that I assume must have originally been >>> meant for nec 8201a. They are a little pcb with a single ram chip and an >>> additional chip probably a decoder of some sort to consume 4 chip-enable >>> lines. I could take some photos of it and maybe it's circuit could be >>> reverse engineered from that. >>> >>> https://photos.app.goo.gl/ZQle2id7AMWdX2bC3 >>> >>> Another option is QUAD, which is a thing that installs in the bus socket >>> and displaces the internal ram with it's own full 32K, plus 3 more banks of >>> 32K that you can switch between. Although you can't get a quad right now. >>> Steven Adolph is testing his latest revision of the design and it's in >>> between right now. He found problems with the old version and so removed it >>> from oshpark, and th new version is not yet verified. >>> >>> But assuming that comes along sooner or later, that would upgrade you to >>> 32K the same as if you had installed all 4 possible modules inside. >>> >>> -- >>> bkw >>> >>> >>> >>> On Wed, Mar 14, 2018, 11:14 AM Gregory McGill <[email protected]> >>> wrote: >>>> >>>> ok is there a source for the 100 chips? or a pcb? >>>> >>>> Greg >>>> >>>> On Wed, Mar 14, 2018 at 12:02 AM, Fugu ME100 <[email protected]> wrote: >>>>> >>>>> Just the 102, it uses a standard pin out. The 100 uses a special RAM >>>>> module. >>>>> >>>>> From: M100 <[email protected]> on behalf of Gregory >>>>> McGill <[email protected]> >>>>> Reply-To: <[email protected]> >>>>> Date: Tuesday, March 13, 2018 at 10:58 PM >>>>> To: <[email protected]> >>>>> Subject: Re: [M100] 8K RAM Chip >>>>> >>>>> oh wait these are 32x8 :) are these ones on ebay for the 100 or 102? or >>>>> both? >>>>> >>>>> Greg >>>>> >>>>> On Fri, Mar 9, 2018 at 7:33 PM, Gregory McGill <[email protected]> >>>>> wrote: >>>>>> >>>>>> if you have the pinouts I have a bunch of 8x8 srams around for TI99 >>>>>> projects >>>>>> >>>>>> Greg >>>>>> >>>>>> On Fri, Mar 9, 2018 at 6:11 PM, Ken Pettit <[email protected]> wrote: >>>>>>> >>>>>>> Ahh, I see now the original email stated 102. So yeah, those will >>>>>>> work. >>>>>>> >>>>>>> Ken >>>>>>> >>>>>>> >>>>>>> On 3/9/18 6:09 PM, Fugu ME100 wrote: >>>>>>>> >>>>>>>> More if it was R/S :) >>>>>>>> >>>>>>>> This is the one >>>>>>>> >>>>>>>> https://www.ebay.com/itm/1-TOSHIBA-TC5565PL-15-64K-8Kx8-SRAM-CMOS-STATIC-RA >>>>>>>> >>>>>>>> M-5V-150NS-28-PIN-PDIP/321974484773?hash=item4af72cbf25:g:ldEAAOSwGotWlWd9 >>>>>>>> you mean? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On 9/3/18, 6:07 PM, "M100 on behalf of Peter Vollan" >>>>>>>> <[email protected] on behalf of [email protected]> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> Wow, a quick check reveals a 8kX8 SRAM on ebay for $3. Didn't those >>>>>>>>> "memory modules" cost about $30? >>>>>>>>> >>>>>>>>> >>>>>>>>> On 9 March 2018 at 17:57, Chris Kmiec <[email protected]> wrote: >>>>>>>>>> >>>>>>>>>> Great, I'll go looking on the intrawebs :) >>>>>>>>>> >>>>>>>>>> You don't happen to have another REX, do you? :) >>>>>>>>>> >>>>>>>>>> Chris >>>>>>>>>> >>>>>>>>>> On Fri, Mar 9, 2018 at 7:01 PM, Fugu ME100 <[email protected]> >>>>>>>>>> wrote: >>>>>>>>>>> >>>>>>>>>>> The chips are available they are standard 8Kx8 SRAM. Should be >>>>>>>>>>> able to >>>>>>>>>>> find some on line. >>>>>>>>>>> >>>>>>>>>>> Unfortunately the QUAD is only for the Model 100, it will not fit >>>>>>>>>>> the >>>>>>>>>>> 102. >>>>>>>>>>> >>>>>>>>>>> Congratulations on your new addition :) >>>>>>>>>>> >>>>>>>>>>> From: M100 <[email protected]> on behalf of Chris >>>>>>>>>>> Kmiec >>>>>>>>>>> <[email protected]> >>>>>>>>>>> Reply-To: <[email protected]> >>>>>>>>>>> Date: Friday, March 9, 2018 at 4:33 PM >>>>>>>>>>> To: <[email protected]> >>>>>>>>>>> Subject: [M100] 8K RAM Chip >>>>>>>>>>> >>>>>>>>>>> Are these available anywhere, or do I have to find a donor system? >>>>>>>>>>> Just >>>>>>>>>>> got a like-new 102, but no memory expansion. >>>>>>>>>>> >>>>>>>>>>> I'm assuming QUAD is no longer being made/sold? >>>>>>>>>>> >>>>>>>>>>> Thanks! >>>>>>>>>> >>>>>>>>>> >>>>>>>> >>>>>>> >>>>>> >>>>> >>>> >>> >>> On Mar 14, 2018 11:14 AM, "Gregory McGill" <[email protected]> >>> wrote: >>> >>> ok is there a source for the 100 chips? or a pcb? >>> >>> Greg >>> >>> On Wed, Mar 14, 2018 at 12:02 AM, Fugu ME100 <[email protected]> wrote: >>>> >>>> Just the 102, it uses a standard pin out. The 100 uses a special RAM >>>> module. >>>> >>>> From: M100 <[email protected]> on behalf of Gregory >>>> McGill <[email protected]> >>>> Reply-To: <[email protected]> >>>> Date: Tuesday, March 13, 2018 at 10:58 PM >>>> To: <[email protected]> >>>> Subject: Re: [M100] 8K RAM Chip >>>> >>>> oh wait these are 32x8 :) are these ones on ebay for the 100 or 102? or >>>> both? >>>> >>>> Greg >>>> >>>> On Fri, Mar 9, 2018 at 7:33 PM, Gregory McGill <[email protected]> >>>> wrote: >>>>> >>>>> if you have the pinouts I have a bunch of 8x8 srams around for TI99 >>>>> projects >>>>> >>>>> Greg >>>>> >>>>> On Fri, Mar 9, 2018 at 6:11 PM, Ken Pettit <[email protected]> wrote: >>>>>> >>>>>> Ahh, I see now the original email stated 102. So yeah, those will >>>>>> work. >>>>>> >>>>>> Ken >>>>>> >>>>>> >>>>>> On 3/9/18 6:09 PM, Fugu ME100 wrote: >>>>>>> >>>>>>> More if it was R/S :) >>>>>>> >>>>>>> This is the one >>>>>>> >>>>>>> https://www.ebay.com/itm/1-TOSHIBA-TC5565PL-15-64K-8Kx8-SRAM-CMOS-STATIC-RA >>>>>>> >>>>>>> M-5V-150NS-28-PIN-PDIP/321974484773?hash=item4af72cbf25:g:ldEAAOSwGotWlWd9 >>>>>>> you mean? >>>>>>> >>>>>>> >>>>>>> >>>>>>> On 9/3/18, 6:07 PM, "M100 on behalf of Peter Vollan" >>>>>>> <[email protected] on behalf of [email protected]> >>>>>>> wrote: >>>>>>> >>>>>>>> Wow, a quick check reveals a 8kX8 SRAM on ebay for $3. Didn't those >>>>>>>> "memory modules" cost about $30? >>>>>>>> >>>>>>>> >>>>>>>> On 9 March 2018 at 17:57, Chris Kmiec <[email protected]> wrote: >>>>>>>>> >>>>>>>>> Great, I'll go looking on the intrawebs :) >>>>>>>>> >>>>>>>>> You don't happen to have another REX, do you? :) >>>>>>>>> >>>>>>>>> Chris >>>>>>>>> >>>>>>>>> On Fri, Mar 9, 2018 at 7:01 PM, Fugu ME100 <[email protected]> >>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>> The chips are available they are standard 8Kx8 SRAM. Should be >>>>>>>>>> able to >>>>>>>>>> find some on line. >>>>>>>>>> >>>>>>>>>> Unfortunately the QUAD is only for the Model 100, it will not fit >>>>>>>>>> the >>>>>>>>>> 102. >>>>>>>>>> >>>>>>>>>> Congratulations on your new addition :) >>>>>>>>>> >>>>>>>>>> From: M100 <[email protected]> on behalf of Chris >>>>>>>>>> Kmiec >>>>>>>>>> <[email protected]> >>>>>>>>>> Reply-To: <[email protected]> >>>>>>>>>> Date: Friday, March 9, 2018 at 4:33 PM >>>>>>>>>> To: <[email protected]> >>>>>>>>>> Subject: [M100] 8K RAM Chip >>>>>>>>>> >>>>>>>>>> Are these available anywhere, or do I have to find a donor system? >>>>>>>>>> Just >>>>>>>>>> got a like-new 102, but no memory expansion. >>>>>>>>>> >>>>>>>>>> I'm assuming QUAD is no longer being made/sold? >>>>>>>>>> >>>>>>>>>> Thanks! >>>>>>>>> >>>>>>>>> >>>>>>> >>>>>> >>>>> >>>> >>> >>> >>
