Jump to content


New Members
  • Content Count

  • Joined

  • Last visited

Community Reputation

18 Good

1 Follower

About Yoruk

  • Rank
    Star Raider
  • Birthday 04/17/1988

Profile Information

  • Gender
  • Location
  • Interests
    Computing, electronics

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. No ideas ? Meanwhile, here are some pictures of my prototype. I use a home made software that analyze and convert PCB pictures designs into a Eagle-CAD project. Holes and via are automatically detected, it also computes signals names continuity. 🙂 Original design from the book : And my prototype.
  2. Hello there, I am currently working on a simple speech synthesizer circuit for my C64. It works with the SP0256 allophone chip. I didn't created anything, I just re-created the board presented in the "Commodore 64 interfacing blue book" by V. J. Georgiou. A full project with ready-made pcb is presented. Here are the schematics : As you can see, nothing complicated. The code is also available in the book, is more or less POKE commands to give the circuit the allophone index. Unfortunately, it doesn't works (weird sound). I manage to probe some points in the circuit with my scope: -the reset goes from low to high at the C64 boot, -some data is incoming on PBx data pins when the program is running, -when powering the computer on, even if nothing is "asked", there is some garbage signal on the "Dout" pin of the IC. (Strange ?). When playing the allophones, I can hear (and see) some variations in the noise, but nothing clear. -my crystal is a 3.27 one, didn't manage to find a 3.12. As explained in the project article, it should only make the voice "higher". I didn't have a nice TTL clock signal on pin 28 or 27, but I think it's normal. (I see high speed "vibrations") My opinion is to think that the SP256 is damaged. I found it on ebay. Looks "new" but I'm not sure at all if it may be already used. Maybe I'll try to buy a new one from another seller... Is someone here familiar with this chip ? Thanks !
  3. I've found some ROM dumps here... http://www.zimmers.net/anonftp/pub/cbm/vic20/roms/ But I'm not familiar with the ".prg" format. The author says that "The files are in PRG format, i.e. the first two bytes contain the starting address.". Looks like this sample starts at $A000 (witch make sense for a game to have the autostart) : This file length is actually 8194 bytes... So I think that I just have to remove the top two bytes before flashing my eproms ?
  4. Well I choose bank 5 to have an autostart feature and 3 to not have it. If this bank can also be used for existing codes that's even better !
  5. Here is the finished board : It was not easy due to the chip configuration. I choose to put them like instead of a single row, it was a bit easier to route !🙂
  6. Perfect answer, many thanks ! My TV is something like 10 years old, I use it with almost all my console and computers systems, I didn't expect a problem. I'll soon try some NTSC games on my PAL system too.
  7. My guess is that the hardware is identical, but the data on tape is different. I mean, there is no hardware differences on cartridges, so... But I didn't manage to find any manual or information online to confirm this...
  8. Hello there, I have an opportunity to buy a STARPATH SUPERCHARGER, US model, (NTSC ?). My VCS2600 is a PAL version. Is there internal differences between a Supercharger for PAL machines and for the NTSC ? (Maybe there is no differences at all...) So to sum up if I bought this one, can I use it on my machine ? Thanks ! 🙂
  9. If you call this a treasure, well actually yes ! I've got a lot of them, that's why I use them in my designs. Of course it could be simpler to use a single 8k chip, but again I created this also for learning reasons 😊
  10. Regarding this board, look like that header pins 17 and 18 (C R/W and V R/W) are nonexistent too, which confirm our analysis. This is the result of my reflections : So I have, if bank 5 chosen : Chip 1 : $A000-$A7FF, chip 2 : $A800-$AFFF chip 3 : $B000-$B7FF and chip 4 : $B800-$BFFF if bank 3 : $6000-$67FF, $6800-$6FFF, $7000-$77FF and $7800-$7FFF
  11. Thanks for the links. The first one is interesting, but they didn't share schematics. The second one does share one, and it actually uses "V R/W" signal. I asked the guy from Tynemouth Software a question about the "V R/W" and "C R/W" signals. The answer is quite simple : The initial read signal from the CPU is the "C R/W". The "V R/W" is the same but gated with the clock, so this signal is a bit shorter. For normal designs it's better to use the CPU one. But he also says that for a simple ROM access I simply don't need any reading signal at all, since I'll always read the memory. So all my ROM /OE pins should be tied to ground. Yes of course it's quite simpler any maybe cheaper to get an existing board, but I really do this for learning and educational purposes, so it's not a problem to spend a few hours on this. 😁 Your advices and help are for sure very helpful for me !
  12. Well I found here the schematics of a "text interface" that As we can see the "V R/W" signal is NC and the "C R/W" is driving the "/WE" pin of a 2016 (static ram ?). But I don't understand how the /OE signal of the top 2716 chip is created... The input gate D of the U4 7405 (pin 9) is connected to... nothing ? Well I can be interested by some scans... I have some time now and I like retro-analyze PCBs so... It could be helpful ! Thanks.
  • Create New...