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About JJB

  • Rank
    Space Invader
  • Birthday 03/12/1968

Profile Information

  • Gender
  • Location
    Wellington, New Zealand
  • Interests
    Pretty much everything electronic & mechanical; returning to the TI99/4a after 25 years
  • Currently Playing
    with FinalGROM99
  • Playing Next
    with DSK emulation on the cheap
  1. Using Tursi's schematic (thanks Tursi, didn't realise it was yours; great writeup) I used a 256Kx8 RAM chip I had lying around and made two 32K pages switchable through unused TMS9901 I/O pins. Still haven't got a use for it though 🙂
  2. I have used several different solutions to add 32K to consoles and none of them had trouble fitting under the shielding. There is at least one IC height space between the shielding and the motherboard due to the TMS9919/29 heatsink. One thing to keep in mind is that, unless you have a specific reason, the speed gain is not spectacular by any means and there are some programs that are incompatible with the 16-bit mod. I have attached the 8-bit mod I have used in my current console. Jochen TI 32k Mod.pdf
  3. I have built one of the citrus3000psi boards (no idea if they are still available). My console now outputs RGB through the video connector. I use a cheap Scart RGB -> HDMI converter from Amazon to display on a computer monitor. Initial image was too red to my taste so I experimented with a resistor in the Red line inside the Scart connector and settled on 68R. Much, much better result that the composite -> HDMI converter I used before. )
  4. Really appreciate the Fortran education here Vorticon; great demos. It has been a very long time, to have it up and running on this restricted hardware is a treat. It would be quite useful if it had some string-handling capabilities added.
  5. Adding 32K would mean either a complete redesign or an additional shield; since there are a couple of (rather easy) ways of adding 32K to a vanilla console already it won't be on the shortlist I think. A hard drive image on SD is something I have been thinking about after chatting to others working on similar ideas. it's certainly doable by changing the DSR and sketches. I am working on remote (network) storage, HD image support could be part of that.
  6. Hmmm yes it would be handy to have listing files as a keyboard shortcut for instance. Probably need to go down the route of a user-defined interrupt (>83C4)? You could shorten the CALL names for starters 🙂
  7. Moving pictures say more than a 1000 pictures: https://youtu.be/MDsME0TLIYE
  8. The last year I have been working on integrating this happy trio with the TI: I have designed a generic Arduino DSR shield for the TI, with the first application the emulation of three DS/SD floppy drives. Have a look at github.com/jambuur/APEDSK99 for all the hardware and software details.
  9. In addition there is an excellent book called "Technical Drive" by Monthy Schmidt; for the project I am working on I did a comparison with Thierry's commented disassembly and there are some differences too. I did try to contact Monthy to see if he was ok with scanning and saving a copy on whtech but no response (interesting chap BTW). His book also contains commented disassembly of the Corcomp and RS232 devices. Any suggestions on the forum how to go about this? Cheers, Jochen
  10. Hi everyone, As my recently purchased console was in bits for some surgery (a lonely 4116 VDP RAM died) and I had to wait for replacement 4164 RAM, I decided to build the speech synthesizer board into the console. I had come across this Mainbyte article (http://www.mainbyte.com/ti99/speech/speech_console.html) but didn't like soldering all those wires to the I/O port and dismembering the speech board. I have come up with an alternative that is easy to build and easy to reverse if necessary. Instead of just using the I/O port I used the cartridge connector. All necessary signals except 4 are available here and conveniently the pins for the cartridge connector have not been trimmed which allowed me to stick a custom connector on its back (see photo 1). I made this connector from a IC socket (the cheap ones, machined ones don't fit). I cut the rows to the required length, roughed the sides up, sparsely put superglue on 1 side, stuck this length on the back of the cartridge connector and then pushed the other length on. It's was a tight fit and after the glue had sufficiently dried it has become a solid connector. I then soldered a piece of flatcable onto my connector and sealed the thing with hot glue. The other side of the flatcable is soldered to a standard 44 pin S100 connector (Ebay). This connects up to the other side of the speech board. 4 signals coming in to the speech board from the console side are not carried through to the I/O connector on the other side: +5V, -5V, SBE* and AudioIn. All 4 are needed by the speech board so we need to connect pins 1,2,43 and 44 of both connectors (see photo 2) To prepare the console for the speech board I glued (epoxy) 2 plastic standoffs to the top cover to secure one side of the board and its shield with 3mm screws. The other side of the speech board is held in place with Velcro (see photo 3). You will need 4 signals from main board's I/O connector: SBE*, Reset* (the Reset line on the cartridge connector is active high so can't be used), Ready* and AudioIn. I used a separate piece of flatcable to solder to convenient points on the top side (just trace pins 1,2,43 and 44 and pick an easy spot to solder to). At the other end I soldered a standard 4 pin connector to connect up to its partner on the main flatcable (see photo 4). Now it's just a matter of securing the speech board and shield (only the component side shield is used) to the top cover, route the flat cable into the cartridge connector cavity and replace the cartridge cover (mind the lip). You probably need to enlarge (a bit of filing) the slot for the cartridge connector if you have used hot glue to secure the custom connector (see photo 5). If you have left enough slack in the flatcables putting together the console is still easy; the extra step is to insert the cartridge connector in its slot before securing the main board. I used Thierry's site for the I/O and Cartridge pinout (see attached PDF for a reference). It's tricky to keep track of which top and bottom pins to use so check twice before soldering Cheers, Jochen Peripheral and Cartridge connector.pdf
  11. Hi RXB, Would you be able to provide more detail? This would be very useful for the following: - I have added 32K in my console but with a bigger RAM (256K) that can be paged through unused 9901 outputs. The extra banks could be used as a storage device (needs battery backup)- Been thinking of adding DSK emulation though the sideport with RAM and an Arduino with SD card capability. The RAM would be loaded with a modified TI Disk Controller ROM at startup by the Arduino providing reading/writing TI disk images on the SD card. BTW there is also an Arduino shield with Ethernet and SD so maybe even a tiny TCP/IP stack would be possible :-) Jochen
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