czietz wrote: Sat Nov 07, 2020 11:43 am
Ok, after my own tests and discussion on the EmuTOS list, here's what we found out: Unfortunately, there is no clean way to handle an floppy access that fails because no disk is inserted. This is because of limitations of the WD1772 floppy disk controller. You can only chose between two unsatisfying options:
1. You keep the drive selected indefinitely. This is what TOS 1 does. You can observe that the floppy drive LED keeps on.
2. You keep the motor on signal asserted indefinitely. This is what TOS 2, 3, 4 and EmuTOS do. It means that after inserting a disk, it will spin until a successful floppy access has been done.
Apart from the visible indication (LED keeps on), the choice #1 can have other more subtle implications, which is why Atari changed the behavior starting with TOS 2. Since EmuTOS handles this case exactly as newer Atari TOS versions do, the outcome of the discussion was not to change EmuTOS (to TOS 1 behavior) in this regard.
I hope I could at least explain to you why.
PS: I'm so used to the behavior of TOS 2 (I rarely use Atari TOS 1) that I never even thought about this; it was perfectly normal for me.
Thank you for this. I'm extremely grateful for this thorough explanation.
US Atari 520 STFM (C070523-001 REV.D1) , Exxos PSU, 4MB Marpet Upgrade, Exxos 6 Chip TOS 1.04 USA, EmuTOS 1.0.1, Ultrasatan, PP Driver, Original Floppy Disk Drive, NEC Multisync EA193Mi Monitor, Star LC-10c Printer, iMP C100110-001 DMA.
