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matthew180 last won the day on August 13 2019

matthew180 had the most liked content!

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About matthew180

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    River Patroller

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    Central Florida
  • Interests
    My family, FPGA, electronics, retro/vintage computers, programming, coin-op games, reading, outdoor activities.
  • Currently Playing
    Divinity2, Borderlands2, beta-testing for Realms of Antiquity (TI-99/4A CRPG).

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  1. IIRC, there is a kit somewhere (check MainByte for "32K on the 16-bit bus" project), and I would be surprised if Thierry didn't do the project his own way as well. The project ends up being more involved than most people anticipate (hardware usually is), and you will need good desoldering skills (and soldering skills, but desoldering is 4x harder than soldering). Somewhere there is also a kit to replace the ROM, which uses a PCB that fits the 90-degree orientation of the ROMs, and probably replaces the SRAM too, but I don't recall. You will also end up with a 1-off computer and broken compatibility with some software because suddenly on your computer all the scratch-pad will be decoded. There is no software that will take advantage of the extra memory, and it will not make the system magically any faster, so ask yourself if the mod is worth the effort, i.e. if you are going to write your own software to use the extra RAM for your own enjoyment.
  2. I have two ATI FirePro V8800 graphics cards (both cards are 2GB with 4x Display Port outputs), and one nVidia Quadro 4000. Make offer. I prefer shipping via USPS flat rate box, but I'm flexible.
  3. There has been a lot of discussion and speculation around the "what if" of the 99/4A. A little searching on the forums should provide you with a few hours of reading. IMO, a flawless 99/4A implementation would not have made any difference as far as the future of the computer was concerned. TI messed up the execution of being a player in that market by trying to keep everything closed, the licensing, and other such factors. Even IBM got greedy and screwed up with the closed nature of the PS/2, despite having TI as an example of "what not to do", just a few years earlier. As for an actual 99/4A being produced that does not have the blunders and flaws, you probably won't ever see it since it would be a one-off system. Some people have created neat systems around the 9995, 99010, etc., and while they do have some software compatibility, they are not 100% compatible, and they are still one-off systems.
  4. That is an amazing haul! That test cart that has "4: PDP TEST" on the label is interesting. I wonder if that refers to a DEC PDP-11 computer? Maybe used for writing initial software or prototyping? Edit: Interesting to see the "9118A" used in a TI product. That was the later version of the 9918A.
  5. The first test after assembling a board is to *always* use the multi-meter to check for a short from any power rail to ground. You do this with the power off. Use the diode beep test if your meter has that feature, otherwise the resistance reading should be at least some tens or hundreds of ohms (3.3V @ 50mA is 66-ohms, for example). If you have less resistance than what your regulator can give (E=I*R, where E=voltage, I=current, R=resistance), then you know you have a problem somewhere. The F18A regulators are 150mA for each 1.2V, 3.3V, and 2.5V. I just measured a working F18A, the 2.5V and 3.3V rails were greater than 10K, and the 1.2V rail was about 230-ohms, so very easy to detect a short if you have one.
  6. Any resistor between 1K and 10K is fine for a pull-up. No need to move it from ground to 5V, the F18A does not need the reset, but it will honor it. Also, depending on where you got the VGA pig-tail, I have seen those fail too, at the soldered wires on the back of the HD15 connector. When doing SMD, or any soldering for that matter, keeping things clean and using copious amounts of flux is critical. Use a quality no-clean flux (for example Kester brand), and a tacky-flux can help keep the parts in place while you work. Use 99.9% alcohol for cleanup, NOT the stuff you get at the store (look up Miller Chemicals 824). Heat control is very important for making good solder joints. There are a lot of videos and such related to soldering, and you have to watch a bunch to find the real ones. The right amount of heat and flux properly applied to the parts will make all the difference. I use a 1mm chisel tip and keep the temperature set at 640 F (leaded solder). Use leaded solder for hobby stuff! Lead-free is so much harder to work with due to the higher temperatures required, you can really kill your parts trying to get them soldered. Use a temperature controlled soldering iron, and a brass sponge (look it up), NOT a wet sponge. Always apply a little solder to your tip before you put it in the holder, and wipe it clean on the brass sponge every time you pick it back up. Hot-air workstations are useful too, but they require a different approach, so you should practice with them before trying them on something you care about. Being able to see what you are doing make the difference between being successful or not. For that reason I always work under magnification (and because getting older sucks). I invested in a stereo boom microscope (AmScope, about $850 on Amazon). With that I can work on stuff all the way down to 0102, but never if I can help it. The MK2 uses 0402 caps and some 1mm x 2mm QFN and BGA parts. It is amazing what you can solder when you can see what you are doing.
  7. Sorry it took so long to post. Here are a few TI photos from my perspective. The guy (Mark Little) next to Jon's table had a pretty impressive 99/4 and 99/4A setup. I really liked the 5.25" floppy drives he had. I love 5.25" drives, the have so much personality and variation. No matter how many I have seen, it seems there are always some I have not. Jon had a nice display of the Tomy, the 99/4A and the CC-40. We had some long discussions about each, and I not know the 99/2 was like the Sinclare and produced the video output via the CPU. It's BASIC interpreter is also token compatible with the 99/4A. Good stuff.
  8. Do they have to be 1st person, or over-the-shoulder view (not sure what that is, 3rd person?). What about top-down or isometric kinds of driving games? Edit: never mind, I should learn to read the topic title.
  9. Let's see, where to start. I'm sure I will repeat some things already discussed, and Tursi's summary is pretty much right on. First, the "F18A Title Screen" was added to help with troubleshooting. The 9918A powers on with everything disabled (all VDP registers reset to 0) and the VRAM in some random state, but that is not very useful when things are going wrong. So, like Tursi said, if you see the F18A Title Screen you know the FPGA has loaded its bit-stream from the flash, you know the 3.3V and 1.2V voltages are ok, and you know the 50MHz oscillator is working. The VGA "output" section is just a resistor DAC and is rarely the problem. Although, a cold solder joint on one of the 100-ohm resistors for the Horz or Vert signals will prevent your monitor from syncing. The LED on the F18A is not technically a "power" LED, it is driven by logic from the FPGA and only comes on when the FPGA has successfully configured (which takes about 200ms). If it is flickering then something is *really* wrong, probably with the power section. The only thing the F18A needs to power up and display the F18A Title Screen are: 5V, Ground, and pull the reset pin high. A 5V power source and 3 wires on a breadboard are about all you need, although I would recommend pulling reset high with a pull-up resistor. The reset pin is a "soft reset", i.e. is only affects the loaded circuit and will *not* cause the FPGA itself to reset; only a power cycle will trigger the FPGA to reload its bit stream from flash. Host communication relies on the level shifter and the one discrete AND-gate IC (next to the level shifter). The level shifter requires 3.3V, but the AND-gate is powered from 5V. If the F18A powers up and you see the F18A Title Screen, it is possible the level shifter or the AND-gate have failed. If the level shifter is kind-of failing, you would expect to see gabled output as the host tries to communicate. But a solid F18A Title Screen would indicate the host is either not trying at all, or all 8-bits of the data bus are blocked. The AND-gate controls the direction of the level shifter for the data bus and is controlled by the host #CSR and #CSW signals. The regulators are VR1 1.2V @ 150mA, and VR2 is a dual 3.3V @ 150mA and 2.5V @ 150mA. The 2.5V is the JTAG reference. All caps are rated for 16VDC (at least the ones I used), but the Absolute Max input rating for VR1 and VR2 are 6V. Any more than that for too long and they will blow. IIRC they have over current and output short-circuit protection. The two jumpers that control the GROMCLK and CPUCLK generation, and their respective output pin are critical for some systems. The 9918A, and thus the F18A, produces the GROMCLK which is required in the 99/4A for GROMs and sound to work, which is critical for normal operation of the console. I had a problem just the other night with an F18A I was repairing that was showing the F18A Title Screen. I had just replaced every IC on the board (the console power supply failed and put 12V on the 5V rail), so I was sure it was not an IC failure, all the voltages were good, and I had video output. The problem turned out to be a cold solder joint on the input of the jumper pins to the FPGA, so the F18A was not producing the GROMCLK, which meant the 99/4A was not operating, which meant the F18A was just sitting and waiting for the 99/4A to talk to it. The jumpers pull the inputs low, and the FPGA has weak internal pull-ups on those inputs, so if you don't have a jumper, the selection for that jumper position will be a "1". The reason for this design decision was, for anyone who was so inclined, to allow switches-to-ground to be used on the jumper pins, i.e. it makes using switches easy in place of jumpers in case you want to make the default-sprite-selection an external switch, etc. Just realize the problem is not always straight forward and you need to understand what is supposed to be happening, and make sure the jumpers are set correctly for your target computer. For example, if you pull all the jumpers and put the F18A in a 99/4A, the computer will not work. But put it in a CV with no jumpers and it will work fine.
  10. I don't know, but my instinct would be to look at the MSX1 for examples, although I learned yesterday that the CV set the bar for the NES engineers to pass, so there is that.
  11. Even if I had finished by this time last year, due to the chip shortage I cannot get a large majority of the parts, especially the FPGA, used on the MK2 right now. So I could not get them made for the last 8 months even if I was done. Hopefully me finishing the MK2 will coincide with parts being available.
  12. Moving the 32K into the console does not make anything faster as far as the CPU bus cycle time is concerned. It might affect the overall performance of the *computer* if 32K console mod avoids the 16-to-8 bit multiplexer, but I have not looked at the mod in detail so I'm not sure. However, changing the crystal in the system, which affects the CPU's clock, that *does* impact the bus cycle time and devices on the bus will need to respond in less time, or introduce less propagation delay. How many people have done those mods is anyone's guess. It is probably best to make your hardware projects so they work with a stock console, IMO.
  13. @tuf @Vorticon Based on the thread for the project, it looks like it is mostly through-hole, with one or two SMD SOICs on the console-side board. But SOICs are easy, you can do them by hand no problem.
  14. Sure, I understand that, but I was trying to stay on topic (answer a question) and provide a simplification to help clarify an idea about propagation delay, rather than getting into hole vs. electron flow through a PN junction, or current vs. wave E and M field theory, etc. For your sake I will go make a correction, since, as you pointed out, it is not the actual electrons flowing from one end to the other that carries the information. Is that satisfactory?
  15. Yes, but this new design does not have shielding. I was just offering information for consideration. And each one has electrical and physical trade-offs and considerations to account for, and there are no silver bullets. Adding capacitance to your high-speed data lines can put you into a world of hurt really fast, and IDE cables are designed for short distances and internal use. The fire-hose is external and typically much longer, so a lot more opportunity to introduce problems. RF, grounding, and shielding is non-trivial. Hopefully this design will "just work" and most of these concerns can be ignored.
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