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TI Professional Computer video problem

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eebuckeye

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Joined
Feb 9, 2008
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35
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I received a TI Pro computer and can not get a good picture using composite or the RGB port. I understand the resolution is not normal which is possibly my problem. I have the TI monitor but it does not work unfortunately. I tried a Tandy CM-5 RGB monitor and get the picture attached. I tried the monitor with a Tandy computer and the screen is perfect and have tried adjusting the monitor with no change.

Any suggestions please? Thank you
 

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The TI Professional’s video system uses an oddball scan frequency that’s about halfway between CGA and EGA, so you’re going to have problems trying to get any “normal” monitor to sync with it. (The “composite” port runs at the same frequency as the RGB port; it was used for mono.)
 
eebuckeye said:
If I install a different ISA video card would that help?
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The TI Professional video is not software compatible with IBM video cards so installing an IBM one the BIOS wouldn't know how to talk to it.

eebuckeye said:
Any other RGB monitors that might work?
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I never tried but some early multisync monitors supported the 17? KHz hsync and CGA TTL level video signals. Looks like the TI 9 pin pinout matches CGA.

https://www.minuszerodegrees.net/manuals/NEC/NEC MultiSync II (model JC1402) - Service manual.pdf
 
djg said:
The TI Professional video is not software compatible with IBM video cards so installing an IBM one the BIOS wouldn't know how to talk to it.
Click to expand...

I wasn’t even sure if the slot pin outs were compatible enough to avoid letting the magic smoke out if you plugged an ISA card into it, but checking the manual it looks like they’re… mostly electrically compatible. But yeah, definitely won’t work. The memory map of the TI is completely different from a standard PC, it starts its VRAM at 0xC0000, not 0xB0000 or 0xB8000…
 
You probably already know most of this, but pretty much everything with both the TIPC as well as the TI Business Pro was intentionally designed to be specific to Texas Instruments hardware. Even software was TI-specific (and thus it failed miserably). Outside of adding a 40MB drive to a Business Pro (which had to be split up into multiple partitions because of the TI-specific version of DOS), I never was able to do much with the one Business Pro I had. Also had a TIPC which had been modified to a 286 (MS-DOS compatible) but it had so many issues otherwise that I let it go for a couple bucks.
 
eebuckeye said:
Unfortunately I didn't know that until now. Is it worth keeping? It seems pretty rare?
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Worth as valuable not really. Have note of $200 for one with monitor and keyboard though missing keys on ebay from some time in the past. Didn't note functional state. It is an interesting portion of early PC history where companies were trying to figure out how to compete with IBM. TI thought the way to compete was to make improvements that weren't software compatible with the IBM PC. Market said otherwise so they aren't that common. Surprise what won in the market was 100% compatible but cheaper.

It was our first PC. The better text than CGA but with graphics capability is why we picked it. Later we did buy an IBM compatible board to put in it to be able to run more software. Convinced mom that I could write software to automate a lot of paperwork for her show rabbit hobby to get her to buy the computer. That worked fine on the TI. Early on TI was able to convince software companies to make the major software packages available for it. When they saw the sales if supporting it was much effort updates stopped supporting it after a while.

Some TI specific software is available
https://www.google.com/search?q=sit...NIgBtwGSAQE0mAEAoAEBwAEB&sclient=gws-wiz-serp

Have some usergroups software also. A lot of user group stuff is programs written for IBM PC that did run on TI. Some are TI specific. VCF directory has some demo disks I made for the TI in the VCF museum.
http://www.pdp8online.com/ftp/software/TI_PC/

I've brought mine to VCF show a couple times
http://www.pdp8online.com/shows/vcfe16/vcfe16.shtml
http://www.pdp8online.com/shows/vcfe21/index.shtml
 
From a historical point of view it’s “worth keeping” because it is one of the more notable machines from that brief window of time between late 1982 and 1984 where people thought the concept of “MS-DOS Compatible” computers that weren’t “PC Compatible“ was a viable idea. (Other machines from this era include the Tandy 2000, the Mindset, Sirius 1/Victor 9000, the HP 150 touchscreen… etc.) It wasn’t completely stupid, after all CP/M had worked despite programs needing extensive customization when moved between machines if they did anything but simple TTY I/O but, yeah, didn’t work out in the end.

That said, of course, it’s going to be more of a curiosity than a machine most people will get much use out of today.
 
eebuckeye said:
Outside of having an original monitor it is impossible or near impossible to find a compatible display?
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It will be some work since you need a multisync that supports TTL CGA/EGA. The one I pointed out supported VGA also switch selectable. The VGA only ones I looked at won't work since they only support >= 31kHz which significantly limits selection. The EGA non multisync ones won't work either. Didn't see any on ebay right now though no easy search term to separate them. No idea how hard they are to find now.

I've heard people using scan converters to convert old video formats to modern video formats. I haven't looked into them so don't know if this is possible for the TI format video.

Any chance you can fix the original monitor?
 
I won't be able to fix it at least. It powers on but no picture at all and brightness does nothing.. I picked it up for $350 with keyboard in good shape, computer and monitor. The shipping method was horrible but the computer seems like it might still work as it beeps, the caps lock on the keyboard works, the drives try to load.. I can return it but seems like it still might be worth keeping?
 
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