TravisS42

Yeah, a lot of Japanese things just don't get noticed elsewhere. Though the SMP 80/X seems to be universally unknown. Surprised by how little Japanese language information there is out there, not much better than English parts of the web. Rather than going unnoticed completely a website might have a sentence about it. Given the number of people interested in retro computing in Japan I thought there would be more, but after talking to a few people there it is clear they are every bit as starved for information. I'm going to try to scan the book I got and donate the hard copy to one of the retro computing groups there.

My irrational want is any of the SORD SMP 80/x series microcomputers. First of all, I think they look great, love the front panel on this SMP80/20. I'm also really interested in them because they seem to be largely unknown. There is very little information about them online, despite being an Intel 8080 microcomputer that was announced and released before the Altair 8800. According to this profile in The Home Computer Advanced Course magazine, it was even fairly popular. A few websites English and Japanese language websites devote a paragraph about them and I've found a document or two with SORD ads but that is about it. I recently picked up a handbook for the SMP 80/50 (Z-80), which seems to be a Z80 version of the SMP 80/50, and it is a model I've never seen mentioned anywhere online. For that matter, aside from this book I've never seen any other documentation online or for sale about any of the models. Sadly it is stuck with my brother in Japan due to COVID-19 shipping issues. But he sent me a few photos and I am intrigued. I don't know what info is actually contained inside, but I have dreams of tracking down more and cobbling together enough information to make an emulator or building a replica. I've attached those photos if anyone else is interested in looking at the little that is available.

@Tursi I don't know how I missed that on the top. I'll blame the bad light and my general tiredness lately. But for curiosities sake I did mange to get the shield off and saw that the silkscreen was definitely wrong. So much like yours, the one labelled +12V is actually GND. Also not sure what happened, but all that fiddling around seems to have fixed something, because the computer turns on now. Keyboard is a mess, but that is a problem for another day. Anyway, it is still good to know about this issue so I won't be confused in the future. Thanks for helping to clarify things.

It might be silk screened incorrectly, but every other example I have found online seems to be the same as this one. I'll take a look, see if I can trace them. Haven't been able to get the RF shield off the board though, seems to be stuck on the expansion port side, and I'm not sure what is going on there.

Thanks for being willing to take a look. My other thought was that perhaps the 4-pin connector on the power supply has different output depending on the version, so that the QI simply expected GND on pin 2, rather than pin 3. But I can't find any documentation about it. Everything I've found focuses on the compatibility of the 2 or 4 pin connector on the power cable, not the power supply itself.

I might be barking up the wrong tree with this, but I looked at this page: http://www.mainbyte.com/ti99/computers/motherboard_ti99qi.html, which shows the motherboard and power supply board for a TI-99/4A QI. I compared them to mine, and I've included both here: Mainbyte TI-99/4A QI motherboard My TI-99/4A motherboard They appear to be the same board. But I notice my power supply board isn't the same. It has a 4-pin connector, rather than 2-pin. It also looks like the one I see listed as the TI-99/4A board, as opposed to the one for the TI-99/4A QI. My power supply board Mainbyte TI-99/4A QI power supply Mainbyte TI-99/4A power supply These are from this page: http://www.mainbyte.com/ti99/hardware/power_supply.html The one in mine appears to be the TI-99/4A one, if that site is to be believed, not the QI one. Is it possible that someone replaced the board and wired it incorrectly? Or did TI often mix and match things, therefore this is a part combination that is normal and something else is wrong?

Thanks, I guess I can try that, though not sure if I'd get anything given the strange voltage issue. The ones I got were from 8bitclassics, and supposedly should be compatible with the NTSC TI-99/4A (https://www.8bitclassics.com/product/5-pin-din-to-composite-av-cable/). Their packaging does indicate yellow should be video.

I recently picked up a beige TI-99/4A and based on the motherboard layout I guess it is a TI-99/4A QI. I am new to these things, so take that with a grain of salt. However, I didn't know if it was working or not so I picked up a 5-pin DIN to AV cable to test it on a modern TV. Sadly, I didn't get a signal through the AV inputs or using an AV->HDMI converter. My first step was to check the power supply output to the motherboard, but I got a strange result and could use some help. I measured from the ground that goes around the board, and these were the results. The GND and +12V seem to be switched for some reason. I notice that they are the in the same order as shown in this video of a TI-99/4A that isn't a QI revision (link should start at the relevant part). Not sure if that is relevant or not. So I was wondering if anyone knows what the problem might be, and how I might go about fixing it. Or just where I should look next to figure out why I don't get any output.