Trs-80 parts?

Okay, sci.electronics pointed me to jameco.com. I found many parts, read full story there.

Anyway, I found an exact copy of my schematics at

On sheet 1 part 4, what is "X71" (split into multiple parts) and "X3"?

help appreciated, poly-p man

X3 and X71 appear to be programming jumper strips. They are 16-pin IC sockets with a plug-in strip of jumper wires that are either open or short, depending on the specific configuration needed in the computer. Ferinstance, X71 appears to be the configuration for setting the computer to see either 4K or 16K of RAM. BTW, see Z33 and Z34?? Those are the BASIC operating system for the TRS80. You will probably have loads of trouble finding a copy of those.

Good luck on building it (and even more luck on making it work).

Cheers!!!!

Ebay looks like your best chance. NEC were making clones of the Z80 until around 2000 some time IIRC

Bye. Jasen

I have 2 rails of Z80's you just want one?

dan

Poly-poly man wrote:

I'm going to be nice and not ask why.

sci.electronics pointed me to

poly-p man

Why do you have so many, though ;)

I suspect his reason for having so many is similar to mine, although I threw away most of my tubes of Z80s years ago.

The Z80 was a very popular microprocessor for use on embedded controllers, ultimately being replaced by the Intel 8086 and later more current processors.

When production of these products ceased once they became obsolet, many tubes of them and other obsolete semiconductor devices ended up in the trash can, or going home with employees.

In my mind the question would be: Why would you want to duplicate a TRS-80 today, since for about the same amount of time and effort you could produce a contemporary computer using, say, an Intel Pentium 4?

Since as a hobby I restore some older computers to operation, mainly Atari 400s and 800s, but I start off with a complete abeit not working machine. If I owned a TRS-80, I would likely try to respore it to operating condition as well. Still, other than a historic collectible, I really don't see any reason to recreated at TRS-80 from scratch. Then too, I may be missing something. Realize that even at the time they were being still sold by Radio Shack, most people, including their owners, referred to the as "Trash-80s", a major reason why most of them ended up in the trash can. It is an understatement that none of them were very reliable and provided such poor performance that virtually none were actaully employed in commercial use.

That said, an original Radio Shack TRS-80 (not a reproduction) is likely a very desirable item for some specialty collectors even today. (Check on eBay to test the market.)

Harry C.

You do realized that you will need the ROM chips from a TRS-80 computer, a TRS-80 keyboard, and a TRS-80 or equiv. TTL monitor... Wouldn't it be easier just to buy a TRS-80, they practically give them away on Ebay... I have 4 of them myself.

You would have more fun and learn more by building a 6502 or Z80 computer from scratch. ...just a thought

The only thing that will be a problem is the ROM ICs. It might take some looking to find a keyboard with just mechanical keyswitches that could be rewired to match the matrix of the TRS-80 computer, but there was nothing really special about its keyboard. Same with the monitor, the original was a tv set with the tuner missing, and if I recall, optocouplers to get the video signal into it. Any North American TV set would work, even better one with an actual video input jack. Any NTSC monitor, and there are lots of them for older computers, CCTV cameras, and whatever, would work.

Keep in mind that someone did convert their existing Z80 computer to a Z80, and wrote about it in "Kilobaud". He did have to get the ROMs, but at that time they could be ordered from Radio Shack. And he had to rearrange some things so his hardware would fit that which the ROMs expected.

It likely isn't legal, but I'd not be surprised if one could find a dump of the ROMs online somewhere.

Michael

Start at

Also try

I saw a complete one of these (with floppies) go on eBay a day ago for about $80 + S&H

someone was getting rid of them!!!

I couldn't pass them up, the thoughts of all the little controller boards I could made with them and all the 2732's and 6116's and 8255's I have

:)

dan

Poly-poly man wrote:

I could dup roms for you, but I dont know what I have a trs80 around anymore....

dan

Michael Black wrote:

What were the RS part numbers? I have some RS masked ROMs from their old "Surprise Packages" around here somewhere. I bought a bunch of them because they had cassette and 8 track DC motors I needed, and the price was right. ;-)

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