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Tandy 1000 & 2000 Service Manual & 1000A Supplement available for download

I

IBM Portable PC

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I’ve recently had a couple of requests for the 1000A Service Manual, which is in fact simply a supplement to the 1000 Service Manual.

While I’m at it, several years ago a few of us here also contributed to buying a very rare copy of the Tandy 2000 Service Manual, and to having the weighty tome professionally scanned.

All 3 PDFs may now be downloaded from here:
https://drive.google.com/drive/folders/122m2_qNxQnQu0bqc3isy3OYG779bMOis

Note that I simply located and downloaded the 1000/1000A documents myself several years ago, although I’m not sure where I downloaded them from.

Please upload and share all 3 on various sites for others who may be searching.

Note that the Tandy 2000 manual includes a rare copy of the Mitsubishi M4853 800K floppy drive OEM technical manual.
 
Thank you for finally putting out there a copy of the 1000A schematics! Bits and pieces of the 1000A supplement seem to be floating around but this is the first copy I've seen that actually has the schematics present. Sometime when I'm really lacking for anything better to do I look forward to sacking out with a copy of this and the Tandy 1000EX/SX era sheets to try to noodle out exactly what differences there are between the various ASICs. The 1000A's unique proto-"Big Blue" video chip is particularly interesting.
 
Oops, I just cross-posted this to IBM Portable PC's original 1000A service manual thread. Oh well, that thread it is still the top Google result for now.

The 1000A information is amazing to have. I was sure that information was lost to time. It is not quite complete - looks like the scanner missed a few pages - it is still packed with knowledge.

Eudimorphodon, it has a similar chip to the SX's Little Blue also.

I uploaded to Archive.org: https://archive.org/details/tandy-1000-a-service-manual-supplement/page/n9/mode/2up
 
This will make a few people very happy!

Overnight I had a thought that perhaps I did not simply download the 1000A Service Manual from somewhere as I had originally thought. Today I checked my email ( I have 22 years worth of email across about 6 accounts in Apple Mail - thank God that it remembers the things that I do not!) and PDF archives and sure enough I actually purchased the manual on eBay in 2013. I had it shipped directly to a scanning company where they experienced some issues with the fold-out circuit diagrams. It appears that they scanned the document three times with varying results. More importantly, I have been able to locate all 3 attempts. The version previously shared, which I did obviously did not check thoroughly at the time, was the final 26 Oct 2013 version. I have now clarified the filenames and uploaded all 4 versions into a seperate folder within the Google Workplaces link from my original post. I guess the next step is to take all 4 versions and merge the clearest pages in Adobe Acrobat Pro, however I do not see myself doing this in the near future. Then again by doing so something may be inadvertently overlooked. Perhaps the 4 attempts, with involved varying settings between scans, is the safest option.

Enjoy!
 
That is awesome, thank you. "Tandy 1000A Service Manual 6 Jan 2014 Scan.pdf" appears to be complete. Perhaps that is one that you already assembled together. I have replaced the version I uploaded to Archive.org with that.
 
"Tandy 1000A Service Manual 15 Oct 2013 Scan.pdf" appears to be complete also - just has one of the 1000A schematic sheets out of order. "Tandy 1000A Service Manual - 6 Jan 2014 Scan.pdf" does have the order fixed and has all the empty pages removed, so I think that is the best one. I will leave 6 Jan 2014 as the version on archive.org: https://archive.org/details/tandy-1000-a-service-manual-supplement
 
JayesonLS said:
"Tandy 1000A Service Manual 15 Oct 2013 Scan.pdf" appears to be complete also - just has one of the 1000A schematic sheets out of order. "Tandy 1000A Service Manual - 6 Jan 2014 Scan.pdf" does have the order fixed and has all the empty pages removed, so I think that is the best one. I will leave 6 Jan 2014 as the version on archive.org: https://archive.org/details/tandy-1000-a-service-manual-supplement
Click to expand...

The scans are very similar, however some schematics are clearer on the later scans.
 
JayesonLS said:
Eudimorphodon, it has a similar chip to the SX's Little Blue also.
Click to expand...

Yep. That's one nice thing about having the schematics, it might reveal whether there'd be any reasonable possibility of adapting some of the SX/EX/HX-era chips to the 1000A for repairs. The video chip is totally out, sure, but perhaps there'd be hope for some of the others. It does put the 1000A in a pretty awkward spot that it has so many unique ASICs in it.

An interesting, and apparently unique, tidbit in there is it says the 1000A's video chip added support for 256kx1 DRAMs, IE, It has a ninth, unused multiplexed address line output, "MA8". Looks like they considered the idea of being able to build a Tandy 1000 with 512K onboard with no need for a DMA chip!

(Interestingly "Big Blue" only has 8 address lines plus a "banksl" signal, which is only used on the EX and HX to switch between its two 128kX16 bit memory banks for 512k of RAM, but the block diagram for Big Blue in the EX tech manual still shows an "MA8" hanging off the multiplexing circuitry. Last minute tweak to take advantage of the 64kx4-bit wide 256kbit chips?)

It does kind of make me wonder if in theory at least it'd be possible to "mad science" together a 512k-onboard 1000A. Not that there'd be any point, but...
 
Eudimorphodon said:
it might reveal whether there'd be any reasonable possibility of adapting some of the SX/EX/HX-era chips to the 1000A for repairs.
It does kind of make me wonder if in theory at least it'd be possible to "mad science" together a 512k-onboard 1000A. Not that there'd be any point, but...
Click to expand...

For the 10 or so pins I checked, the keyboard interface/PIO IC is identical to the one in the SX. I don't know why they have different part numbers - bugs maybe, or perhaps different manufacturer. Also possible I suppose that some of the internal logic is a little different.

The other two, I don't think so. The timing IC has different pinout and has some functions not present in the Little Blue. I had figured this much out before we got the manual and was not looking forward to the amount of effort needed to reverse engineer it. It was quite a treat for this manual to show up out of the blue.

My interest has been to develop a turbo upgrade with SX timings. So far, it looks like it may be easiest to recreate most of the timing IC with programmable logic. That would also be a OK approach to make a chip replacement. I have designed this on a smaller scale for the original 1000 where I recreated the functionality of the Intel 8284 clock generator in a 16V8 GAL. It tested OK standalone - waiting on boards to arrive so I can test in a 1000.

The PLCC IC - replacing that with something else seems like a much more work than I want to sign up for. On the plus side, Tandy 1000's seem to be very robust.
 
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