Re: [hatari-devel] Improved timings for the FDC emulation

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

On 07/12/2013 22:54, David Savinkoff wrote:
> - EmuTOS displays only Drive B: when both floppy drives are turned
>    ON (AND) NO hard drive is specified. (should display both drives)

For this, better wait for a new emutos version, as Roger told some fixes 
were needed in Emutos

>
> - TOS 2.06 UK crashes with 4 Bombs when both floppy drives are turned
>    OFF (AND) NO hard drive is specified. (please try on real ST)

I get the same crash ; this is where it happens :

$e01208 : 2038 04c2                            move.l    $04c2.w,d0
$e0120c : 3239 0000 0446                       move.w    $446,d1
$e01212 : 0300                                 btst      d1,d0
$e01214 : 674c                                 beq.s     $e01262
$e01262 : 2f39 0000 0a0c                       move.l    $a0c,-(sp)
$e01268 : 4e75                                 rts

but content of $a0c is 0.l, so this jump to $0, hence the crash (I don't 
know what $a0c is supposed to hold)

When drives A/B are off and gemdos if off, $4c2=0 and $446=0 (boot drive 
number). So it seems TOS checks if the selected boot drive was detected 
as enabled, and if not it jumps to an undefined location that causes the 
crash.
This seems strange that TOS would crash when no drive is available, but 
this would need to be confirmed on real HW, we never know, TOS had bugs too.

This could also be caused by some of the memory init we bypass in stMemory.c

Nicolas