Posted By
ytm
on 2024-10-03
18:48:33
|  Re: FlexSD firmware for SD2IEC drives, V1.3.0 fw
GEOS 128 used the same IEC fastloader as GEOS 64, this is already supported by sd2iec firmware.
The original GEOS 128 didn't use any burst features. All the disk drivers were almost exact copies of those from GEOS 64. They only had to change the code to enable/disable I/O from manipulating $01 into $FF00.
Yes, my 1571 burst disk driver doesn't use any drive code, just U0<0,2,4> commands for block read/write/inquiry. It's much shorter than the original.
I just wanted to check how it would perform comparing to the original fastloader. It turns out the speed is almost the same, so it was not worth pursuing this further, but it's a nice example of block-read and block-write commands.
Here is the boot disk image: https://drive.google.com/file/d/17qJ4FBybRc5i_inv3LSWuR0a5lFjZlhX/view?usp=sharing
And here is the relevant code: https://github.com/ytmytm/geos/blob/feature-drv1571burst/drv/drv1571burst.s
The only interesting parts for you would be next to __ReadBlock / __WriteBlock (around line 913). There is nothing original here, it was mostly lifted from the 1571 User's Guide.
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