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Full Schematic for TRS80 Model 4/4P

Robbbert

Robbbert

Experienced Member
Joined
Jan 10, 2019
Messages
446
The Technical Manual only has excerpts, but I'm after the complete diagram of the 4/4D/4P models (Gate Array and the older one), that is clearly readable.

Can someone point me to a good source?
 
The Service Manuals for all those models should be on archive.org. At the very least the 4pNGA/4pGA Service Manual is there. I don't have a Model 4, so I never looked for that service manual.

Tom
 
I raided archive.org yesterday, unfortunately the manual was the same as the others - no full schematic.

Thanks anyway.
 
Found it at last, in another copy amongst other stuff. Problem solved.
 
The file is uploaded here: https://we.tl/t-80zaoqF9U2 (WeTransfer)

Like any file sharing site, make sure you have all your adblocking and virus scan tools at the ready - I had no ads or popups, so I have no way to know what dangerous things might be there.
 
Robbbert said:
The file is uploaded here: https://we.tl/t-80zaoqF9U2 (WeTransfer)

Like any file sharing site, make sure you have all your adblocking and virus scan tools at the ready - I had no ads or popups, so I have no way to know what dangerous things might be there.
Click to expand...

Thank you for that link. This is SO MUCH better than the 4/4P technical manual file I already had!

-Alex
 
Thanks for sharing. It is very good readable copy. The only down is that it is just for non GA version.

I now know that there is a very good copy of GA manual with schematics - I just got it from a kind sole here through private message. I did not ask for permission to publish it, but I hope I will not offend anyone if I share it with other forum members who would ask in private.

I just wished that the well known sites would have these copies.
 
Another kind soul just found that the manual with schematics in question is actually available in public domain at archive.org. I would not reveal that soul's identity, just say that the nick is NoPizzaTonite, with my thanks of relieving me from the duty of distributing the link to the said document on my google drive in private. Thank you, and everyone else - enjoy the link above
 
Sorry to dredge up this old thread, but the we-transfer link is expired, and it seems easier to add documents to archive.org than to find them there. I am looking for the schematics of the non-Gate Array model 4P. These are not in the 26-1080 Service Manual. This only has the Gate Array schematics.
Greeting,
Fred Jan
 
Fred Jan,

First, a big thanks for your great and long-lived Model II information archive; I've found it very useful for a long time.

Now, are the schematics on PDF pages 71 - 77 of the service manual PDF at archive.org's 26-1080 page not the ones you're looking for? In rereading them a few minutes ago it sure looks like the NGA 4P schematics, with the various PALs and the 1793 FDC.
 

Hi lowen,​

Thanks for the heads-up, the problem is obvious with me reading large scanned PDFs (making the scan is easier :)).

The schema is indeed what I was looking for. My Model 4P appears to not showing the 64x16 screen, but does show the 80x24 screen. The boot-ROM RAM test (RESET & .) is visible (in 64x16). The board is the 8709427 REV PP3, which is hopefully close to the PAL (=non-GA) schema.


Greetings & thank you,
Fred Jan
 
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