This is a facinating topic and piece of Atari history.
Just a few questions to see if making a MOD kit for SF354's or SF314's would be possible...
flashjazzcat, on 10 Nov 2014 - 12:40 PM, said:
Someone needs to clone that controller board so we can mod our otherwise useless ST floppy drives.
PS I read on her site that's she's back in business. And she could add the second SIO port.
Yes, someone making PCBs would be great use for the ST drives out there to convert them to 8-bit use rather than changing our XF551's!
Even modifying the controller PCB to handle DS-DD for ST SF314's in stead or just copy it and make MOD kits for SS-DD for a ST SF354's mod kit.
I think the expectation is that we can learn what command puts it into DD mode. That would give us a 320K drive.
Obviously, engineering wasn't quite done with the design... not ready for PrimeTime at the FCC.
This is really a collector's item - you shouldn't hack it.
I agree, but fixing the ROM so we could modify SF354's would be great!
Quick look at the code, it has commands R, r, P, W, S, !, N, O, H, ". There a couple of others but am going to bed as am falling asleep at keyboard. will try and figure out what some do latter.
The other 3 commands are R, P, W with high bit set. It doesn't appear that high bit set means anything at this point. The H command appears to set high speed sio, a similar speed to the XF551. All bytes sent/returned after the H command is issued with a $01 in one of the aux bytes will be at high speed except for the command frame. Once high speed is set, Instead of A (ack) returned for command Acknowledge, a H is returned. To turn off, issue a H command with 0 in aux bytes.
A custom dos required for this baby.
How hard would it be to patch the ROM so it doesn't need a custom DOS if we wanted to make a mod kit for SF354's?
Digging a bit more, it appears the full single sided 80 track disk is treated as a double sided 40 track disk.
Also the percom block can return either 26, 18 or 16 sectors per track. Need to dig more to see which densitys do what.
The percom block aux byte returns $48 (H) if in high speed mode or $41 (A) in normal speed mode. The XF551 returns $41 always.
Edit: It won't work on PAL computers. The sio routines are not patched.
"the full single sided 80 track disk is treated as a double sided 40 track disk" Do you think that is to keep be compatible with the XF551 for the software already out there as Bryan suggests?
How does that compare with
Could the ROM sio routines be patched so we could modify SF354's for PAL 8-bitters as well?
Wow, that's kinda clever as it would have made it completely compatible with software for the XF551.
Could you please try to format a disk DS DD 40 tracks, 16 sectors per track. This should get a working format of 1280 odd sectors with the XF351.
The single density format you done, does dos think it was successful but it wasn't? Only way to tell is to read beyond sector 720 and see what happens.
Bob were you able to test beyond sector 720 to see if it really was successful?
Edited by Defender II, Fri Nov 21, 2014 11:28 PM.