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Seeking AT&T 6300 Service Diagnostic Diskette


Experienced Member
Jul 26, 2020
I am searching for the AT&T Service Diagnostics Diskette that service technicians would have used to test, evaluate, and repair the 6300’s. I have the customer test diskette but that doesn’t yield much information. I thought some of you may have seen it at one time or another or know someone who I could contact to acquire a copy of it.

Actually, I am having difficulty printing from the parallel port. I sat down today to print something from my AT&T 6300 machine and received an error “write fault error writing device lpt1.” The file was a standard text file using a print command from DOS 6.22. I then tried the simple command dir > lpt1 and got the same response.

I don’t have many test-related tools for this machine. So, I put faith in the Microsoft Diagnostic Version 3 (MSD) to at least give me a hint of what may be going on. Under the LPT1 listing, I found some odd factors. Paper out and Busy was yes. I unplugged the printer cable and received the same response.

I can’t seem to find any doc’s on the MSD on the Internet to explain the findings from the MSD. I am asking what you might use to identify why the LPT1 is failing? In addition, I have a loopback plug on the serial and parallel port. I tried testing again with no change in results. That is sort of why I am seeking the AT&T Service Diagnostics Diskette. Thanks to all that respond.


Experienced Member
Mar 2, 2022
Chicagoland, USA
for those who pass this way on their travels....

I couldn't follow the ftp:// old skool link , but the same files are available on archive.org or in the zip below,

link to files
run the system.exe

If you are repairing the AT&T 6300, there is great help "Service Manual" http://www.olivettim24.hadesnet.org/docs/PC6300SM.pdf for instructions on the system test go to section 5-54

and good luck to you !


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