Re: [cc65] Atari sector size detection

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From: Shawn Jefferson (
Date: 2002-10-28 17:34:29

Attention Christian:

Have you been following the thread I started in comp.sys.atari.8bit?  Here is some information that Stefan Dorndorf replied with:

>In 6502 code you can do this:
>LDA #DRIVENO ; number of disk drive to check (1 to 9)
>STA $301
>LDA #'S     ;  S means STATUS check
>STA $302     
>JSR $E453   ; Disk-Interface-OS-Routine (this will call SIO)
>BMI ERROR   ; Error occured (e.g. Disk drive switched off)
>AND #$20    ; check Bit 5 of $2EA for Double Density
>BNE DOUBLE    ; double = 256 bytes/sector
>BEQ NOTDOUBLE  ; not double = 128 bytes/sector
>Unfortunately, this doesn't work on the XF551. You will need some more
>complicated code to do correct density check on the XF551. Please post
>a message, if you're interested. (SpartaDos can't handle the XF551.)

There is some arguing that SpartaDOS detects and uses the XF551 perfectly fine though.  I know I've used mine with it ( >v3.2f) before with no troubles. Maybe this code will help you?

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