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hhos

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About hhos

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  1. The "DSK1." part of the file name is the device name. The object code is the device name and file name to which the output of the assembler will be stored. You probably have the option to send that output to an alternate device with Classic99, like "DSK2", "DSK3" or another device supported by the emulator.
  2. The data that he uses for the displayed characters is complete. It is at time index 7:19. Once you have that you would just have to choose positions to put them onto the screen, poll the joysticks and display characters as desired, according to which bits are set.
  3. Maybe you could write the program and send it to him? Then he could make another video with that in it.
  4. There is a listing in the E/A manual on pages 404-406. The description of the ISR, DSR, etc. usage of this memory, as described on these pages, has such a large foot print that I have thrown out any idea of allowing the current interrupt system any access. I don't know of any other list, and I've seen this one referenced every time I've seen the subject come up, as far as I can recall anyway. HH
  5. Since that's exactly what I was looking for I guess it'll have to do. Thank you. HH
  6. That is much better than what I had. Thank you. Are there any other guides in the same place you found this? I am looking specifically for V9958, but would be interested in many others. HH
  7. According to this at least one wait state, after A15 toggles LOW, is needed when accessing GROM. "Solving the GROM access problem....... But there is a problem here: the cicuitery that generates this holding signal is fairly complex (two 74LS138, and two 74LS03). As a result, it takes time for SysRdy to go low after A15 has toggled. If we remove wait state #4, the request for a hold actually arrives too late for the CPU to take it into account. The situation is even worse with zero-wait-states timing, where there is no way the signal can get there in time." According to my understanding one wait state after A15 toggles LOW is all that is ever provided by the circuitry around the 74LS194 (wait state generator). HH
  8. I'm not advocating this mod so much as evaluating it. I just analyzed what it is doing, realized how easy it would be to include fully populated Scratch Pad, and wrote up something on it. It is here essentially because I think this is a simple, cheap and effective way to speed the TI99 up. I figure, for that very reason, quite a few people have used it, and don't realize with a little bit of time, solder and wire, they could add just a little bit of out of the way memory. This mod also leaves a number of unused resources which could be useful for further expansion, some of which could start to resemble aspects of your system. There's not enough to put together a paging system for the RAM blocks, but it would be a cheap start. Right now, my focus is on designing a system that only uses technology that was available in the early 80s. No FGPAs or CPLDs. PALs are out simply because even if I can find them, the expense would be too great. GALs, PALCEs, PEELs, and similar chips programmed with only the capabilities of a PAL chip are OK. And, of course, I will use SRAMs that weren't available in the 80s, also because of availability and expense. As the system matures I'll allow more modern technologies into the design. The first goal though, is to make it as fast as I can with 74XXX technology chips. This one also adds 64K, no wait states, to the console. It just uses only 32K of it. It is a minimal expansion to give a developer an idea of how his software would play on an early 80s machine, and then on an 80s machine with zero wait states. At least that is how I look at it. I'm assuming that since you can switch RAM into the memory I/O space, that you use the CRU to switch the 8K blocks in and out? Where did you map that into the CRU space? I might put that into my next mod. How many wait states do you have when accessing that external RAM expansion? Only on VDP access? How many wait states does it insert? I believe GROM is even slower than VDP, possibly because it is on the 8 bit side of the MUX? What about GROM access? And the other memory mapped devices? Sound chip? Speech Synthesizer? Anything else? I'm still looking at ideas for my own TI99 mod design, but this one still looks like a good basis to start with on the first one. Yours sounds like it will be more similar to my #3 or #4. Does your modified system use only legacy 74XXX chips? PALs or GALs? Something more sophisticated? HH
  9. I modified a couple of the pictures from the Ballmann-Clulow project to show the jumpers and soldering points. There are two pictures in the attached file. You only follow ONE of them. They both have the same result. It's just a question of whether you want to cut a trace, or pull/cut one pin on each of the two 6810s. Pulling/cutting the pin looks easier but, sometimes it's a little tricky pulling the pin. You might break off the pin from the chip, or pull the trace up off the board. Cutting the pin is easier. Just be careful, in either case, when you solder your wire into the hole underneath the bent up pin. Cutting the trace is the easier way to go, especially if you feel you lack soldering skills. There is just one more point to solder to, and about 5 times the length of wire for the jumper, but each solder point is unobstructed, and there is virtually no chance of accidentally pulling a trace away from the board. HH CG_32K_console_1K.Scratch.tar.gz
  10. BEWARE: I have not tested this but, it is so simple and I can see no reason for it not to work. If you have already installed this 32K console SRAM mod, then it won't take much more work to fully populate the RAM space at >8000 to >83FF. That would give you 1024 bytes instead of just 256. It seems to me that disconnecting the CS* from the 6810s and moving that signal over to pin 4 of U504 C2 (first remove the +5VDC from it) should be all that is necessary. I see two possibilities for doing this. I think this might be the easier of the two but, you may find other possibilities that I didn't consider. The signal could be removed from the 6810s by cutting the trace coming from pin 8 of U507. Run a jumper from pin 8 of U507 to pin 4 of U504 C2. Do not forget to remove the 5VDC from pin 4 prior to connecting this jumper, though. Cutting this trace at this point cuts off the connection to U606, pin 12. In all likelihood, you would want to reestablish the connection from U507, pin 8 to pin 12 of U606. This would be required, if you have the defeat switch installed, so the Scratch Pad memory would still be fast memory when the switch is in bypass mode. The 2nd solution I came up with was to pull or cut the CS* pin on BOTH 6810s. Then run a jumper from the hole that is left under pin 11 to U504 C2-4 (again, remove the 5VDC from it first). This doesn't break the connection to pin 12, U606, so nothing more should have to be done. Alternatively, you could remove both 6810s from the board since they will not be used anymore. I intend to leave them in, possibly to be used as a small buffer for another idea with which I have been toying. I made up schematics for what I call the Clulow-Guion 32K upgrade, and I am attaching them to this post. They are intended as an addendum to "Hardware Manual for the Texas Instruments 99/4A Home Computer" by Michael L. Bunyard. The largest difference between the CG32K and the BC32K is the CG32K can be switched back and forth between 0 wait states and the normal 4 wait states using a toggle switch. I don't think you can hot swap it, though I can't offer first hand test results. Even though I am going to use this as a basis for the 1st stage of my own design, I do not intend to use a toggle switch to bypass the zero wait state in mine, so chances are that I never will test a hot swap of this particular mod. I want to be able to hot swap mine via software, and perhaps a mechanical push button. Instructions for the three current Ballmann-based mods are found here: http://www.mainbyte.com/ti99/16bit32k/32kconsole.html Please let me know if you think I'm in error with the schematics or the modification I've suggested. If you try it and it works, please let me know. If it doesn't work... well, that's your fault for trusting me. Clulow-Guion_32K.upgrade.tar.gz
  11. I finally got around to looking at this project, which I am calling the Clulow-Guion_32K upgrade, located http://www.mainbyte.com/ti99/16bit32k/32kconsole.html Actually not that hard to figure out once you get the pin #'s on those piggy-backs straight. I initially had almost half of them bass ackward . Figuring out where the 2-input AND on U613, pin 13 for the wait state bypass defeat switch was a bit confusing, but I think I got it now. Your mod has 64K RAM and only 32K is used? Did they put some of the extra memory into that space, or do you still only have 256 bytes in the >8000 to >83FF address area? It only has 256 bytes. There may be enough unused logic gates in there now to implement a 1024 byte scratch pad, though. There's certainly enough memory. There is no attempt to accelerate Video, Cart, or GROM access. That, in part I think, would explain the lack of acceleration when running console BASIC, or XB. When I'm certain of the placement of that AND gate I'll post a revised schematic. And, if I can figure it out quickly, maybe a way to mod this mod for the 1024 byte Scratch PAD (not a high priority for me at the moment since the 32K expansion would be just as quick w/ this mod). HH
  12. Thanks, Ksarul. Thanks, Fabrice. I'll be wary. Were any of the errors in the last six pages? Those schematics of the TI99/4QI are the only part of this manual that I am using. Can you direct me to a list of the errors that you have found? HH
  13. I found this: http://www.mainbyte.com/ti99/man/ti99_tech.pdf It appears to be what I was looking for. It has what appears to be a board layout for a 99/4, then schematics for a 99/4A, and then schematics for the 99/4QI. Thanks, HH
  14. "It" would be the Bunyard book I take it? That is the one that I have been using. Thanks, HH
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