Too bad I don't have a 200; you're probably right but since it's not clearly defined in the data sheet I'll have to dig out one of my other systems using a 2764 and check it for myself ;-)
But I have to ask: why pull pin 27 to Vcc? What happens if you pull it low? On Sun, Nov 13, 2022 at 9:06 PM Brian K. White <[email protected]> wrote: > 27C64 can't be used as-is. > pin 27 is A15 and needs to needs to go to a non-existing 2nd OE or CE. > > You'd need an adapter board that combines pin 27 (A15) from the socket, > with pin 22 /CE0 (/BANK#1) from the socket, to produce a single /CE to > pin 22 of the chip. > > You could do that with a single 2-gate NAND part the same as in this > model 200 RAM > https://github.com/bkw777/TANDY_200_RAM#single-bank---sop > > https://raw.githubusercontent.com/bkw777/TANDY_200_RAM/main/TANDY_200_RAM.svg > > That is using one nand gate just to invert /CS1 to CS1, > then ANDing those to make a single CS, and inverting that to make a > single /CS output to the chip's /CE > > The point is getting the job done with only 2 gates of the same type so > it's all from a single part. > They even make little 8-leg parts with just the 2 needed gates. > > For 27C64 you'd need to do that with /CE0 from bus pin 22 and CE1 from > bus pin 27, to produce a single /OE to chip pin 22. And chip pin 27 > pulled to VCC by anything from 100k to a plain trace. All other pins > including /CS would go 1:1 socket to chip. > > > On 11/13/22 19:38, Mike Stein wrote: > > Duh; shoulda looked more carefully; it really IS A15 (not A13) and it > > goes to /CE1 (or CE1); double duh! Thanks, Brian. > > > > So it looks like the only non-standard pin is pin 27, since 26 is not > > used. Has anyone actually tried a JEDEC standard 27C64? > > > > Pin 27 is the Program pin which looks like it might effectively be an > > active high OE (since there is no program voltage. > > > > m > > > > > > > > On Sun, Nov 13, 2022 at 5:27 PM Brian White <[email protected] > > <mailto:[email protected]>> wrote: > > > > 8k. > > > > HN61364 = 8k > > A15 is connected to a chip select to enable/disable the whole chip > > (really just output enable not chip enable despite the /CEx labels), > > and the actual address lines are only A0-A12 > > > > It's mostly like 27C64 but with 3 OE lines, customer programmable to > > be either active high or low as part of the mask programming. > > Although the schematic labels them as /CE0 /CE1 /CE2, really they > > are all OE not CE, and it appears that /CE1 should be shown as > > active-high, so really: /OE0, OE1, /OE2 , and /CS is a normal actual > > whole chip enable, active low. > > > > I was just now in the middle of drawing up an adapter for that chip > > like FlexROM_102 but for that chip, to facilitate using the main rom > > replacement feature of REX Classic in a 200 the way I have already > > for 100 and 102. > > > > But it may be simpler to make a different kind of adapter that > > replaces both chips with a single larger chip on a single adapter in > > the main rom socket and simply remove the 8k chip. The /BANK1 line > > goes to both chips the same, and A15 ends up activating one or the > > other exclusively at any given moment. > > > > bkw > > > > On Sun, Nov 13, 2022, 4:48 PM Mike Stein <[email protected] > > <mailto:[email protected]>> wrote: > > > > Looking at the schematic, are you sure it's 8K and not 16 > (27x128)? > > > > Looks standard except for pins 26 & 27 > > > > On Sun, Nov 13, 2022 at 4:23 PM Stephen Adolph > > <[email protected] <mailto:[email protected]>> wrote: > > > > Georg, > > What type of ROM chips did you use, when you replaced your > > ROMs with patched versions? > > I've been pondering what the simplest way to do that is. > > The 8K M13 socket is wired oddly, and doesnt seem compatible > > with a 27C64. > > thx > > Steve > > > > On Sun, Nov 13, 2022 at 12:30 PM Georg Käter > > <[email protected] > > <mailto:[email protected]>> wrote: > > > > Hello together, > > > > I own a M200 "German/EU Version" (Art.Nr. 26-3860H) > > w/modem, for German market it was delivered with set of > > keyboard > > > > caps and a data tape including driver for keyboard and > > printer. I tried this in VirtualT and it seems to work > > so far. To run REX > > > > on my M200 I replaced original ROM by ROM from VirtualT > > patched to serve german keyboard mapping. > > > > For your reference I´ve added original ROM files and > > files from tape for your reference. > > > > Regards > > > > Georg > > > > > > Georg Käter > > Gangolfsweg 44 > > D-52076 Aachen > > Tel. : +49 2408 7194987 > > Fax. : +49 2408 7196758 > > Mobil : +49 171 4839954 > > E-Mail : > > > > [email protected] > > <mailto:[email protected]> > > > > ========== Ihre Nachricht > > ========================================== > > > > *von* : Cedric Amand <[email protected] > > <mailto:[email protected]>> > > *gesendet* : Sonntag, 13. November 2022, 15:37 > > *an* : [email protected] > > <mailto:[email protected]> > > *Betreff* : [M100] custom key mapping generator for > > Tandy 200 > > > > __________ Originalnachricht > > _______________________________________ > > > > My point exactly Brian ! > > How did they come up with that idea ? It makes no > > sense. It really prevents you from using the option > > rom socket. > > The docs does not talk about removing it. > > And even if you could remove it ; the installation > > procedure of that ROM is not easy at all, requires > > to type two "calls" with the freaking keyboard > inverted. > > OK - us nerds 40 years later can do it easily, just > > type "CQLL", but imagine explaining that to a random > > journalist in 1984 ?! > > Especially as the french doc (which I happen to > > have) says to type "CALL" not CQLL. > > I also wonder if other markets are affected by this > > plague, > > If anyone here lives in germany and owns a qwertz > > (or other keyboard variant) of the M200 : do you > > have a "stock option ROM" as well ? > > I also wish to thank Stephen publicly for the time > > he invested into helping me, as indeed, you can't > > use an option ROM (and even less a REX#) in those > > non-qwerty M200s, and I think this research might > > help some other people at some stage (this hobby is > > booming right ? :) ) > > We're (and I am) in the process of replacing the > > main rom + 8KB rom with a 27C512 flashed with a > > custom "native Azerty" firmware > > Which should free up to option socket, for a REX# > > I also plan to make other modifications to that > > custom ROM, but we'll see if I get there. > > I've also been experimenting in the past with custom > > firmware for the my M102 for different reasons. > > I'm a "modem" nerd and I have all the equipment > > (PABX, etc) to make voice calls between my vintage > > laptops - so it's important for me to have my modems > > work. This required a custom firmware to make my > > M102 work, with modem, with a REX#. ( OK I think > > this kind of stuff is only relevant to me this time > > :) :) > > Le 2022-11-13 14:53, Brian White > > <[email protected] <mailto:[email protected]>> > > a écrit : > > > > Nice. > > So the point would be to make the main rom > > natively azerty to match the hardware, free up > > the option rom slot for normal use, without > > otherwise changing the main rom so that it > > becomes incompatible with application software? > > I guess you might even be able to make a dvorak > > version and move the keycaps around? > > I'm just trying to imagine the sales pitch for > > that azerty 200 that needs the option rom, thus > > preventing the use of any other option rom (or > > at least making it pretty inconvenient by having > > to swap them on every reset I guess?) > > "Here's your new model 200. It's only half as > > useful as others with no modem and no option rom > > but you can still pay full price please." > > -- > > bkw > > > > On Sun, Nov 13, 2022, 8:28 AM Stephen Adolph > > <[email protected] > > <mailto:[email protected]>> wrote: > > > > hi folks, > > Thought I would share this work. It is a > > spreadsheet for computing the keyboard table > > in the T200 so you can make native custom > > keyboards for T200. > > Why? > > The AZERTY keyboard in Europe was > > accommodated using an option ROM that kinda > > hacked the keyboard. Keystrokes get > > intercepted and corrected to be AZERTY even > > though the main ROM is set up for QWERTY. > > An alternative is to have the main rom > > directly support AZERTY. > > To do this, there are 6 keyboard mapping > > tables that start at 9763h. Each table are > > 44 bytes long. > > This spreadsheet lets you assign the ascii > > codes for each of the 44 affected keys, for > > all 6 tables. (unshifted, shifted, GRAPH, > > shift GRAPH, CODE, Shift CODE). > > It is an excel spreadsheet that included the > > analysis add it so that certain needed > > functions are present. > > Once you make the correct keyboard mapping, > > the spreadsheet provides the 6x44 bytes in > > assembly compatible form, so you can compile > > and patch the tables with a hex editor. > > This approach could be used for other > > machines also. > > Note - the AZERTY keyboard did NOT modify > > the actual character set, so that is out of > > scope. Of course it is possible to patch > > the main ROM to change the bitmaps as well. > > Not handled by this spreadsheet. > > Comments welcome. > > Steve > > > > > > > > __________ Ende Originalnachricht > > __________________________________ > > > > *Vertraulichkeitsinformation: > > *Diese Nachricht ist vertraulich. Die Informationen > > dieser Nachricht sind ausschließlich für die persönliche > > und vertrauliche Verwendung durch den/die oben genannten > > Empfänger bestimmt. Wenn Sie kein beabsichtigter > > Empfänger sind, bitte lesen, kopieren und verwenden Sie > > die Nachricht nicht. Machen Sie sie nicht anderen > > zugänglich. Bitte informieren Sie uns umgehend über den > > Zustellfehler und senden Sie die Originalnachricht > > per E-Mail an uns zurück. > > > > *Confidentiality Notice: > > *This message is confidential. The information contained > > in this message is intended only for the personal > > and confidential use of the recipient(s) named above. If > > you are not the intended recipient, please do not > > read, copy, or use it and do not disclose it to others. > > Please inform us immediately of the delivery error > > and return the original message to us via e-mail. > > > > -- > bkw > >
