Hans23
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Posts posted by Hans23
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Nice, thank you both! I'll give the OSSC at try, I have one here and never tried it with the TI.
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20 minutes ago, pixelpedant said:- Using a European console, which outputs a much cleaner YPbPr signal (but needs 50Hz compatible display).
The tms-rgb that I mentioned converts the YPbPr signal to RGB. This might not be necessary as YPbPr is commonly referred to as component video and there should be TVs that can directly display it. I tried with my Samsung screen but finally gave up and went the RGB route. Do you know of any working solution that converts the YPbPr output produced by the TMS9929A to a standard component video signal?
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I take it that you're using a video monitor connected to the console using a DIN-5 adapter cable, and you are located in the US. If that is the case, your best bet is an F18A which gives you a VGA output and adds a 80 chars per line mode, which is nice for coding. If you have a european console, you can also acquire a tms-rgb board. It is soldered underneath the video controller and gives you a clean RGB signal (15 kHz). You will need a monitor that can operate with that scan rate (e.g. CBM 1084 or a TV with an RGB SCART input).
I'm still building F18A boards and if you're interested, fill out my form to get onto the waiting list. I'm currently waiting for the FPGA chips that I ordered to arrive, but once they do, I'll be able to build another bunch of boards.
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5 hours ago, Nelno said:The main challenge I will have is PCB design. I have exactly zero experience with PCB design, so I'm learning as I go. Currently trying to get a good workflow for FreeCAD to PCB design software.
KiCad is very popular among open hardware projects. I found getting started with it rather easy, and a library for Kailh switches exists, not sure if it contains the one you need though. You're probably far enough into the project not to want to switch tools, but if you struggle with FreeCAD, maybe KiCad is worth a try.
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The 7053 sync separator comes in handy if you happen to have displays that support the refresh rate, but not SoG. At $139, it is pricey when bought new, but sometimes one pops up on eBay. It does the job well, but it needs a separate power supply which I find annoying.
Most high-end Eizo displays support SoG as they were specifically marketed to be used with workstations. I got an Eizo S2100 (21'', 1600x1200) and an L685 (18'', 1280x1024) off eBay and had good luck with both of them on various machines that I had.
There is the Sync on Green DB which may be useful for selecting a suitable monitor, although it is focused on PS2 use and thus does not tell you whether the higher workstation resolutions are supported.
Good luck!
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I've stopped soldering in the JTAG adapter and instead program the flash using the TL886II+ - This is much faster than using the pesky Xilinx tools.
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5 hours ago, mike_z said:If I install a socket for the 9901 will that interfere with the F18A connection?
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.
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59 minutes ago, wierd_w said:I would like to install a chip socket in place of the VDP, and then install the F18A on the socket
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.
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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.
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2 hours ago, broettger said:What is the approximate cost?
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
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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.
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11 hours ago, J-Data said:SMT soldering isn't that bad, just need patience and some good flux
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.
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8 hours ago, ralphb said:When I clicked on that link, I got:
This website is currently experiencing high load, which is causing strain on our systems. Please try again in a few minutes.
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.
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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.
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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
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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
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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
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2 minutes ago, RickyDean said:I'll take them, you already have my info, and I can pay with paypal. If they have not been spoken for thst is.
You got them. I'll get in touch directly.
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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.
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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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11 hours ago, InsaneMultitasker said:5. Suggest wrapping some electricians tape around this area to protect the traces when you insert the card into the Peripheral Expansion Box.
The board apparently works just fine, at least for the FD controller part - One just needs to talk to it the right way
I've put on some isolation to prevent PEB casing shorts. I also socketed U29 and U39 to make further repairs easier, but as I don't have these in stock, I'm leaving the original parts in.
Thanks for your input!
Hans-
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From this thread, in which I inquired about some mods I found on a Myarc HFDC and that made me wonder whether they're causing the controller to not work. I've checked the TTL chips on drive side of the board and they appear to be OK. After cleaning off the flux, I've reinstalled the mods that were present when I received the card, here's photos of its front and back:
1 hour ago, InsaneMultitasker said:2. U8 modification is suspicious; that connection is part of the floppy data separator circuitry. Is it a blown trace or intentionally removed? The black mark (Sharpie marker?) obscure the board trace.
The trace between U9 (74LS373) pin 5 and U17 (7406) pin 5 was intentionally cut. Here's a close shot of the trace:
1 hour ago, InsaneMultitasker said:3. The disc capacitor may be correct; some HFDCs had them installed in this manner. What does the wire connect?
It connects pin 5 of U17 to pin 12 of U9, so apparently the mod corrects an incorrect connection between the two?
Any further guidance will be appreciated.
Thanks,Hans
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Hi,
I'm looking at @Schmitzi's Myarc HFDC which is not working - It responds on the bus as normal, but no HD activity is ever seen. As I only have limited testing abilities at this point, I'm first inspecting the hardware for obvious faults and defective TTL ICs. So far, I have not found anything. What I did find on the board, however, is a couple of hardware modifications that have been made and that don't quite look like factory mods:
U38 - Output 1Y wired to inputs 2C0-2C3:
Br
Interrupted trace between U8 pin 5 U17 pin 3.
Capacitor and rewiring under U17:
Diode under HDC9223.
The mods looked a bit dodgy due to the flux residue, but as they're all over the board, I'm unsure whether these are factory or aftermarket mods. Does anyone know?
The EPROM on the board is labeled "H11", and it seems that there are v14 and v16 images floating around. Any ideas what might work best would be appreciated.
Thanks,
Hans
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Replacing PEB On/Off Switch
in TI-99/4A Computers
Posted
My PEB has a similar problem - It seems to be caused by the case breakout being a tight fit and the switch being mounted so that it bends easily. Other than replacing the switch (which I'd find a bit ugly), has this problem be solved by others and how?
Thanks,
Hans