Hans23 Posted August 29, 2021 Share Posted August 29, 2021 Hi, I received a console for repair and it has this 32k RAM expansion built in: It has a (leaked) NiCd buffer battery connected to the two "ACCU" pins on the upper right corner. The IDC connector goes to the console like this: I hope that the CPU is not dead, as that'd be quite an ordeal to move over. In any case, some info on the RAM board would be useful, in particular as I would like to know whether any traces on the motherboard were cut for the installation. I have certainly looked for such modifications, but the cables don't exactly make things easy Thanks, Hans 5 Quote Link to comment Share on other sites More sharing options...
globeron Posted August 29, 2021 Share Posted August 29, 2021 Never seen the board, but maybe this helps. @Tursi / harmlesslion Also in the Dutch TIjdingen magazine in 80's are instructions how to built 32K in the console. With help of the "Regio Zeeland" team i got my first 32K and then load assembly games via cassette player. (See my channel Youtube TI99VIDEOS for more details). 1 Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted August 29, 2021 Share Posted August 29, 2021 That one looks like the board Jürgen Stelter from the TI Workshop Wiesbaden designed. I think it originally came with a page or two of instructions. 4 Quote Link to comment Share on other sites More sharing options...
Tursi Posted August 29, 2021 Share Posted August 29, 2021 There's no need to cut traces unless you are changing the operation of the multiplexer, so as long as it's not an accelerated 16-bit RAM mod, it should be fine. Quote Link to comment Share on other sites More sharing options...
Hans23 Posted August 29, 2021 Author Share Posted August 29, 2021 I did find a cut trace on the board now, but I have not yet figured out what connection is broken by it. The console works - without the RAM extension connected - when I reconnect the cut trace. The board does not look very complex and if I can´t find any documentation, it might be possible to figure it out. The large number of connections that are made to the motherboard make that a project that I´d not want to immediately jump onto -Hans 2 Quote Link to comment Share on other sites More sharing options...
Tursi Posted August 29, 2021 Share Posted August 29, 2021 I'm not offering (yet), but if you post high res pics of both sides of the PCB, maybe someone can make an educated guess to get us 80% of the way there 1 1 Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted August 30, 2021 Share Posted August 30, 2021 I only was able to find this pictures, but it´s a 32K PEB-card from Jürgen Stelter, not the inside mod. 1 Quote Link to comment Share on other sites More sharing options...
Hans23 Posted August 30, 2021 Author Share Posted August 30, 2021 The 10 minutes ago, Schmitzi said: I only was able to find this pictures, but it´s a 32K PEB-card from Jürgen Stelter, not the inside mod. The card on the pictures is a PEB card, but the description is for the internal board that I am faced with Most of the important information is on the first page, but if anyone happens to have the second page, I'd be interested. Thank you! Quote Link to comment Share on other sites More sharing options...
Hans23 Posted August 30, 2021 Author Share Posted August 30, 2021 (edited) For those who don't read German: This internal 32k card uses the 16 bit data bus and it attaches directly to the CPU. There is additional logic on the board to provide wait states to make it work better with the TMS9929A VDP. I tested it without wait states and a F18A installed and it works fine, although I did not immediately have an idea how to measure the speed difference. Here is a full set of pictures: P.S.: I like the crusty 74LS03 which is older than the TI-99/4A itself Edited August 30, 2021 by Hans23 6 Quote Link to comment Share on other sites More sharing options...
+mizapf Posted August 30, 2021 Share Posted August 30, 2021 I just had a look for my old TI console which was equipped with the internal 32K RAM expansion. I cannot remember, though, who installed that expansion. At that time I was about 17 years old, I was able to solder things, but I don't remember whether I was responsible for this cable mess. It was not my father, I am quite sure, because we went separate ways concerning computing in those days. As you can see, there are two buttons (yellow = LOAD, red = RESET) and a flip switch, supposedly for turning on the wait states. 10 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.