[Coco] CoCo Disk Basic and head banging

[Rick Ulland]

Thank you for clearing this up. Don't mind not knowing, hate getting it 
wrong.

-rick


On 1/1/22 6:01 PM, Robert Gault wrote:
> For most of us there will be head banging with floppies because Disk Basic ignored this issue. I wrote a patch for the Disk ROM and included code to prevent head banging regardless of the type of floppy drive.
> I assigned a byte in low RAM as last drive used. When initializing Disk Basic, that bytes was set to $FF. Each time Basic needed to read or write to a disk, the new code checked to see if the drive had changed by comparing the needed drive with LASTDR. If there was a difference, and there always was at turn on, the drive was told to read the head address: #$C0 sent to $FF48.
> So knowing where the drive head was located, there was no reason to attempt to move the head an arbitrary number of tracks to a lower number which might actually be a "negative" one.
>
> Sent from AT&T Yahoo Mail on Android
>