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May I suggest you check your system and directory tk headers: 43 57 TK 58 NB 76 01 08 Remove any "NB" noise bytes in your image and restore the length of each edited track by adding a byte at the end of the track. If that doesnt give you a bootable image then use RAWDUMP and clean manually as above....

Or hexbin util provided with WinOSI will convert two, hex, CR to bin. Follow it up with CLEAN for those noise bytes!
Good to see your progress Rich. I have a C4 version of your boot ROM done and a diskloader version that allows Exmon useage for snooping around DOS65.

Just brilliant ! My order on the way thanks Bill. Nice see someone else using the Premier ROMS - good potential here for some easy program editing with Toolkit and using Cegmon windows with the extended BASIC commands. I have more code coming that makes the system even more flexible... PS no noise i...

Good luck. Hate those intermittent faults. Any corrosion on the board?

Your top diagram shows an typical emitter follower. Low impedance drive was the objective. Wouldn't hurt to add to 600s. Is there a link to that diag? The 540B one I have is not like that. Yes that trace mod looks right. Make sure its isolated from pin1 and 5V ( untested ). CRT are nice in the winte...

If the noise is still evident on a CRT then it could be the mux of video and cpu access with VAS at U56 on a RevB and D Connect 02 clk from CPU to U56-2 after cutting trace to U56-2. Apply the same technique to a 540B- maybe at U6F-2 and check C36. (Untested) Impedance mismatch will cause signal deg...

The Monitor ROM source needs a correction: keyboard = $df00 keyboard array.

How does it look on CRT monitor Jeff ?

Danny, Give me a day or 2 and I think I can sort this ...

Jeff , welcome , please create a new topic in the projects forum and we can help you further.
Also a user hardware & software profile is helpful to all.