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Hans23

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About Hans23

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  1. If you use pin headers like the below with your F18A, you'll be able to get enough clearance to make it sit above the socketed TMS9901. The Mill-Max pins that I use are too short for that. They're chosen to make the F18A fit into the machine with the RF shield installed. Without it, there is enough room in the console to fit the higher construction, and it is probably also better in terms of getting the heat out.
  2. Here is a Blog article with a description of the F18A installation, with pictures.
  3. TI already has you covered: The VDP is in a socket (at least in all machines that I have seen), so all it takes is pull the TMS99(18|29)A and put in the F18A - No soldering is required.
  4. I have been asked whether I include printed installation instructions with the F18A boards that I might - I do not, and that could certainly be a problem to the less electronics savvy. The process is straightforward, but it requires opening the console and routing the cable outside of the case requires some creativity. If you've never opened your TI-99/4A, here is a guide that describes the process. Once you're in, you need to locate the TMS9918A (or TMS9929A) VDP chip and remove it. The chip is the 40 pin chip covered with white termal paste. Here is a video that almost shows how to remove it from its socket - Almost because the person in the video only lifts the chip from one end, bending the two pins on the other end. Instead, lever the chip out with a small screwdriver from both sides, in an incremental fashion. Install the VGA cable on the F18A - There is a bump on the cable that needs to face down when it is plugged into the pin header on the board. Then install the F18A in the VDP socket with the "PIN1" pointing to the center of the motherboard. Due to the other neighboring components on the board, there is only one way to plug in the F18A, the cable connection will run over the neighboring 40pin chip. Make sure that you firmly press on the F18A board so that the pins completely go into the socket. If you want to reinstall the RF shield, you'll want to remove the small aluminum block that is mounted opposite to the VDP on the upper part of the shield. If you want to mount the VGA plug permanently on the back of the machine, you'll need to make a cutout in the RF shield that allows you to install and remove the VGA cable when the RF shield is installed. I leave the RF shield off, which makes things easier. Remember, however, that the VGA cable restricts how far you can flip the motherboard over, you'll have to be careful lifting the motherboard once the cable is installed. Also, the cable is a rather tight fit, so you way want to make the cutout in the RF shield large enough to allow you removing the F18A from the board without taking off the heat shield. I put a warning label "F18A installed" on the bottom of my motherboard to remind me to be careful when lifting it up. Please let me know if you need further installation help with the boards that I've built. I'd also appreciate if we could see some photos by people who have installed theirs for inspiration. I'm away from my workshop for a few days so it will take me a bit before I can provide photos of my installaion.
  5. The cost of the parts runs down at about $50. I need an hour to build a board. I'm leaving it up to everyone to make a sensible bid. -Hans
  6. I've put Matthew's BOM into a Google Sheet. I can report that I've sent out 15 F18A's at this point. Some have been received and and installed. A few people have not received their board yet, but even after the current list is empty, I still have parts and PCBs left. If you're interested in getting a board in May or June, put yourself onto the list.
  7. Nicely done! One thing that you might want to correct is the VGA connector. When the pins are fully pushed through the PCB, you don't get enough clearance for the cable. It might be okay with yours, but I have started to only put the pins into the board so that they are flush to the underside, giving me more space in the machine.
  8. Hans23

    SDD 99

    That kind of performance is ... suboptimal. 🙂 Indeed, and I did not mean to say that this particular service is the way to go. What you'll probably need is a service that provides you with two functions: Retrieve the list of available time zone names, and retrieve the rules for one particular time zone by name. That way, you'd be able to convert UTC as provided by the NTP server to local time. Doing it this way, however, would create a dependency on an external service which might not be desirable if the SDD99 is also supposed in standalone mode otherwise. In the end, though, the tzdata distribution is not all that large and it might be more robust to include it in the SDD99 distribution and parse it in the firmware if you have enough space.
  9. Hans23

    SDD 99

    For an Internet connected device, it is probably best to retrieve the timezone offset from an online service like http://worldtimeapi.org/api/ or similar.
  10. Hi, as I'm progressing with F18A builds, here is some additional information that may help if you're trying to do the same: Matthew's original PCB layout on CircuitMaker.com is missing a trace to one of the voltage regulators. I've patched the first bunch of boards that I built, but I have now fixed the layout. The Gerbers for that version are in this file: F18A_rev_B_-_Hans_Gerber (1).Zip. A version of the BOM is available in this Google Doc. The four 2mm pitch jumpers can all be connected to ground if the device is used in a TI-99/4A. Instead of programming the Flash chip using JTAG and a Xilinx platform cable, one can program it using a suitable programmer and adapter (e.g. the TL866II+). The binary file that goes into the ROM is attached here: f18a_250k_v19.bin. Going this route will prevent you from having to get the ancient Xilinx ISE 14 development system to work. Cheers, Hans
  11. Annoyingly, the FPGAs have still not arrived, so I'm unable to build any more F18As right now. I hope that they get through customs in the next days, but it seems that they are being looked at much closer than other stuff that Aliexpress shipped to me and that has already arrived. Anyway, in the mean time, I have looked at how to get sound output from a machine with an F18A - this topic has certainly been covered before, but I'd like to summarize it for those folks who are late to the party like myself: Sound is coming out of the AV DIN plug on the back side of the TI - even when the F18A is fitted. With an NTSC console, all it takes is a DIN5 to RCA adapter cable which should be easily available. The pinout is like this: Annoyingly, the PAL console uses a 6 pin 270° jack, and ready-made cables are not available for that. The best solution is to replace the 6 pin jack by the standard 5 pin version, which has a compatible footprint. In addition to replacing the jack, one also needs to rewrite a jumper to correctly connect the ground pin. Here is a photo of the PAL version: Here is the same detail on the NTSC version: I have a couple of these jacks and can send them alongside the F18A to owners of PAL consoles that want to make this conversion. Cheers, Hans
  12. I've sent out a small number of boards, but production is stalled as I'm waiting for parts to arrive. I hope to be able to finish a few more next weekend. -Hans
  13. You got them. I'll get in touch directly.
  14. Hey, I was given a collection of homebrew TI hardware that smells 1980ies DIY all over and that I don't really want to keep. If anyone's interested in these things, they're free if you pay postage. Here's what I have: Some EPROM card - The EPROM contains unknown-ti-rom.BIN. Some I/O interface? Looks like an EPROM programmer for the cartridge port. A H.Martin module with 32K SRAM fitted - There is a stack of the 8K RAMs to the right.
  15. I ordered two TMS9900's on Aliexpress a few months ago because I had a machine with a bad CPU and the ones that I received work fine. The TMS9900 is not very likely to be really fake in the sense that it is not likely you get a completely different chip labeled as TMS9900. The reason for that is the uncommon case that the chip comes in (at least if it is a TI chip, I have also seen second-source CPUs in a more standard case). In any case, the vintage chips you can buy on Aliexpress are often used chips that have been desoldered and often cleaned or remarked to make them appear new. For that reason, it is important that you test them as soon as you get them so that you can have yourself be refunded if they don't work. This is a seamless process in my experience, just open a dispute and get your money back, no questions asked. Swapping the CPU is not particularly easy due to the size of the chip. You'll need a good desoldering pump and some patience. The PCB is not particularly delicate, but there is no solder mask between pins of one chip, and sometimes there are traces going in between two legs. Make sure that you do a thorough inspection after you've removed the CPU.
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