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Hi Dave, thanks for the reply. Ok, that's great. I couldn't understand why the /CS0 line was pulsing like that. The reason I've been thinking I have an issue is the following: After I fixed the issue with the D&N board with replacing the 74LS27, I put the board back in and saw that I was now only ge...

Here is a video showing me toggling through the $0400 address space in the OSI monitor while probing the /CS0 and /CS1 lines. $0400 address means that /CS1 should be enabled and the other /CS lines inactive. http://www.neoncluster.com/temp_items/Media/502_OSI_CS.MOV While I'm doing this the followin...

Hi Mike, Yes, this drive writes fine on the C4. I'll try replacing the cap(s), and see if that has any effect. Just to be sure, are you talking about the cap(s) at C8 and C9? I'll also check the ACIA TXData line again, but I couldn't see anything that looked out of place. I've still been battling th...

Hi Dave, Thanks for the reply. I also thought the RAM problem might be an issue with U26. I must have previously put a socket at U26 and put a new 74lS138 there, although I can't remember doing that, so it must have been a while ago. I removed the 74lS138 and dropped in another one, but the problem ...

UPDATE: D&N board now works (not the disk write part thought) and the C2 can now reset. The issue was the 74LS27 at U5. In fact the only IC I didn't have in my parts bin. Typical. Now I also seem to have a small issue with the 502 board with a RAM in and around the $00FB and $0200 addresses (first t...

Oh well, now the system had died. I was reseating the 74LS85's at U12 and U13 and suddenly the system wouldn't start, and just showed a screen of garbage. I tried again and was able to get it to reset just once, but that was it, can't reset anymore. Removing the D&N board allows the system to boot, ...

Hi Jeff,
I just emailed you some disk images for OS65D 3.3 and 3.2 for the C2/C4.

Phil

I have now changed out nearly every IC in the disk section of the D&N board. The only IC I haven't changed is the 74LS94 au U74 because it's the only one on the entire board that is soldered with no socket...and still I have the write issue!!!

Hi Jeff, Thanks for your thoughts. Yes, the schematics are towards the back of the manuals which can be found here: http://www.osiweb.org/manuals/DN_MEM_CM9.pdf Actually, very occasionally there is a 2 bit set such as 81 or 11 etc. And as dumps go, the one I posted above is cleaner than most. Usuall...

Last update for tonight: Now that I have discovered what seems to be a transient bit that seems to propagate through the data being written to the floppy, I thought this would be pretty easy to spot when probing the WRITE line with the analyser, so tonight I tried again. I sent 00's to the floppy as...