atrax27407 Posted October 6, 2017 Share Posted October 6, 2017 Texas Instruments made two versions of their TMS2564 (which is an 8K EPROM). The more common version is a 28-pin package that is still difficult to find. The most difficult version is the 24-pin package. It was used in the TI DSDD FDC. It appears that all of the 4K EPROMs (i..e., TMS2532, 2732, etc.) have address lines numbered A0->A11. The 8K chips (2764) have address lines A0 ->A12. I am looking for the datasheet for the TMS2564 24-PIN package. I have been unable to find it on ;line. Can anyone help me out? I know it muxt exist somewhere in cyberspace! Quote Link to comment Share on other sites More sharing options...
+helocast Posted October 6, 2017 Share Posted October 6, 2017 (edited) Sorry - mask rom vs. eprom Worst case. Here's some other resources: https://console5.com/wiki/ROM_64Kb:_8k_x_8-Bit_(24-pin) and if you have to go the adapter route: http://ist.uwaterloo.ca/~schepers/sockets.html TMS4764.pdf Edited October 6, 2017 by helocast 2 Quote Link to comment Share on other sites More sharing options...
+helocast Posted October 6, 2017 Share Posted October 6, 2017 [ 1 Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted October 6, 2017 Author Share Posted October 6, 2017 I have that one. The TMS4764 is a PROM not an EPROM. I need that data sheet for the 24-pin TMS2564. It looks like the AM27C49 might work but I need to see how it compares with the TMS2564. Quote Link to comment Share on other sites More sharing options...
digdugnate Posted October 6, 2017 Share Posted October 6, 2017 is this it @atrax? TMS2564.pdf 1 Quote Link to comment Share on other sites More sharing options...
+helocast Posted October 7, 2017 Share Posted October 7, 2017 I have that one. The TMS4764 is a PROM not an EPROM. I need that data sheet for the 24-pin TMS2564. It looks like the AM27C49 might work but I need to see how it compares with the TMS2564. No, I understand. I caught it was a rom and not eprom, but there doesn't seem to be a way to delete replies (only edit). You're welcome to my entire 1984 catalog attached, but I'm only seeing 28-pin versions in Chapter 6. Sorry. 1984-MOS-Memory-Data-Book.pdf 1 Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted October 7, 2017 Author Share Posted October 7, 2017 I have it on the highest authority (Jim Fetzner) that the AM27C49 will work in place of the 24-pin TMS2564 package. And I quote: "It should work--but you'll have to shift pins 18, 19, and 21 to get the address lines in the proper order. . ." Quote Link to comment Share on other sites More sharing options...
RickyDean Posted October 9, 2017 Share Posted October 9, 2017 This may have some useful info about a variety of eproms: https://www.mikesarcade.com/cgi-bin/spies.cgi?action=url&type=info&page=ROMref.txt Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted October 9, 2017 Author Share Posted October 9, 2017 Many thanks!!! Buried amongst the details, were the pinouts for the elusive 24-pin package of the TI TMS2564. If my programming adapter works for the AMD27C49s. I can make a socket adapter for it to fit in a 24-pin TMS2564 socket. Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted October 9, 2017 Author Share Posted October 9, 2017 I was mistaken. The last four pins were continued on the next page. Alas! It is the 28-pin package. I'll have to keep looking. Quote Link to comment Share on other sites More sharing options...
RickyDean Posted October 9, 2017 Share Posted October 9, 2017 I was mistaken. The last four pins were continued on the next page. Alas! It is the 28-pin package. I'll have to keep looking. Maybe here? https://console5.com/wiki/ROM_64Kb:_8k_x_8-Bit_(24-pin) Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted October 9, 2017 Share Posted October 9, 2017 Here's a nice diagram showing how to cross the pins on a 27HC641 to use as a 2364 (or in our case, a 24-pin TMS2564). Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted October 9, 2017 Author Share Posted October 9, 2017 There appear to be very few of the 27HC641s available - even on eBay. The going price seems to be about $10-15 per chip. Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted October 9, 2017 Author Share Posted October 9, 2017 It also appears that the AM27C49 and the 27HC641 (by MICROchip) are "pin identical". The MiniPRO does NOT support either one directly without an adapter. I'm working on an adapyet for the cheaper (and more readily available) AM27C49. I believe that I have the pinouts figured out. Quote Link to comment Share on other sites More sharing options...
CPUWIZ Posted October 9, 2017 Share Posted October 9, 2017 Look for 68764C, it is a 24 pin 8K EPROM. They are rare, but I have them. 1 Quote Link to comment Share on other sites More sharing options...
CPUWIZ Posted October 9, 2017 Share Posted October 9, 2017 1 Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted October 10, 2017 Author Share Posted October 10, 2017 I had a bunch of Motorola MCM2532Cs. I found that they were impossible to program with most modern USB-powered programmers. It seems that the problem is that they aren't very tolerant of undervoltage programming. They require an absolute 25V to work. The TMS2532, on the other hand is very tolerant of undervoltage programming and program consistently at 21V. Quote Link to comment Share on other sites More sharing options...
+acadiel Posted April 5 Share Posted April 5 Old topic, but tossing this out here. You can program a 28 pin 2564 and just throw the lower 24 pins in a 24 pin socket and it should be happy. I am using one to replace a 2364 Commodore ROM and just going to bend the upper pins in and tape them. 1980_TI_The_MOS_Memory_Data_Book_for_Design_Engineers.pdf 3 Quote Link to comment Share on other sites More sharing options...
humeur Posted April 5 Share Posted April 5 (edited) This eprom is 24 pin 8K https://deramp.com/downloads/mfe_archive/050-Component Specifications/Motorola/Memory Components/Motorola MCM68764.pdf JL Edited April 5 by humeur 2 Quote Link to comment Share on other sites More sharing options...
CPUWIZ Posted April 5 Share Posted April 5 8 hours ago, humeur said: This eprom is 24 pin 8K https://deramp.com/downloads/mfe_archive/050-Component Specifications/Motorola/Memory Components/Motorola MCM68764.pdf JL Pointed that out 7 years ago and I still have a bunch. 4 Quote Link to comment Share on other sites More sharing options...
+acadiel Posted April 6 Share Posted April 6 22 hours ago, CPUWIZ said: Pointed that out 7 years ago and I still have a bunch. Want to part with one? I’d love one to replace a 2364 which I don’t have enough clearance to put a 28 pin 2564. 🙂 Quote Link to comment Share on other sites More sharing options...
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