rom4x/rom4x/B0_C552_patch_bootfail.s
mgcaret c4b1070329 Simplify bootable ramdisk detection. Jump to AppleSoft if no boot device.
I discovered that there are more than one ProDOS boot block in the wild, so I
simplified the check for recoverable RAM disk to check card for $01 and then
anything besides $00 and $FF since most uninitialized RAM tends to have one of
those two values.  This is slightly more rigid than the boot code checks for.
I added a jump to AppleSoft if no bootable device is found.  I changed the
message a little bit, too.
I also added notes about the feasibility of using the RamFactor firmware.
2017-01-12 19:40:55 -08:00

19 lines
251 B
ArmAsm

#include "iic.defs"
.text
* = $c552
jsr setnorm
jsr init
bra cbtfail
.dsb coma-*,$ea
bra coma ; Make sure coma routine exists
.db 0 ; rom4x present
cbtfail jsr setvid
jsr setkbd
lda #>(nbtfail-1)
pha
lda #<(nbtfail-1)
pha
jmp swrts2