diff options
Diffstat (limited to 'bootblocks/boot_fpy.s')
| -rw-r--r-- | bootblocks/boot_fpy.s | 91 |
1 files changed, 70 insertions, 21 deletions
diff --git a/bootblocks/boot_fpy.s b/bootblocks/boot_fpy.s index ef1f21a..a40d0fa 100644 --- a/bootblocks/boot_fpy.s +++ b/bootblocks/boot_fpy.s @@ -3,36 +3,59 @@ ! ! cat boot_fpy.bin monitor.out > /dev/fd0 ! -! Warning: Disk errors currently cause a hang. -! The boot sector does not end with $AA55 this is not a problem -! with the BIOS but many boot managers will not boot it. ORGADDR=0x0600 -EXEADDR=0x06E0 +EXEADDR=0x0800 ! This must be up to 0x7E0 or 0x0800 LOADSEG=0x0080 ! Must be 512b aligned for DMA +! Padding so you can join with 'cat'. .org EXEADDR-1 -.byte 0xFF ! Marker +.byte 0 + +! This marker is needed by many boot managers (and bochs) but the BIOS does +! NOT require it on a floppy. +if EXEADDR=0x0800 +.org ORGADDR+0x1FE +.word 0xAA55 +endif .org ORGADDR entry start public start start: - mov ax,#$07C0 ! Relocate to ORGADDR - mov ds,ax xor ax,ax - mov es,ax - mov cx,#256 - mov si,ax + mov si,#$7C00 mov di,#ORGADDR + + mov ss,ax + mov sp,di ! Or si or ax + + push ax + pop ds + push ax + pop es + + mov cx,#256 cld rep - movsw + movsw jmpi go,#0 go: - mov ds,ax ! Setup SP & S-regs - mov ss,ax - mov sp,#ORGADDR + +! Grrr, have to load sector 1 in by hand. +if EXEADDR=0x0800 +Loopi: + mov ax,#$0201 ! Read 1 sector + mov bx,#EXEADDR ! Into EXEADDR + mov cx,#$0002 ! From sector 2 + xor dx,dx ! Of the floppy drive head zero + int $13 + jc Loopi +endif + + mov si,#Boot_message + call puts + mov ax,[a_text] ! How many sectors to load mov cl,#4 shr ax,cl @@ -51,7 +74,7 @@ go: ! But occasionally some older machines have really poor BIOSes ! (Some modern ones too) so once we know how many sectors to read ! we switch to reading a track at a time. But we only try it once - ! for each track, normally, as long as the load address is sector + ! for each track. Normally, as long as the load address is sector ! aligned, this will work every time but with some BIOSes we can't ! read a track without messing with the BPB so if the track read ! fails it's one try we fall back to sector reads. @@ -62,10 +85,11 @@ go: ! your BIOS is one of the bad ones you'll have to format your disks ! to a 2:1 interleave. ! - ! BTW: There are some versions of superformat that incorrectly - ! calculate the inter-sector gaps and end up squeezing the sectors - ! to the start of the track. This means that only a full track read - ! is fast enough. + ! BTW: It's very easy to make superformat incorrectly calculate the + ! inter-sector gaps so it ends up squeezing the sectors to the start + ! of the track. This means that only a full track read is fast enough. + ! I suggest you use fdformat as it always uses 'safe' parameters for + ! a 1440k floppy. ! AX = count of sectors mov cx,#2 ! CX = First sector @@ -176,12 +200,37 @@ bad_magic: retf sect_error: - ! TODO Error. - j sect_error + ! Disk error, wait then reboot. + + mov si,#reboot_msg + call puts + + xor ax,ax ! Wait for the user. + int $16 + jmpi $0,$FFFF + +puts: + lodsb + cmp al,#0 + jz EOS + push bx + mov bx,#7 + mov ah,#$E ! Can't use $13 cause that's AT+ only! + int $10 + pop bx + jmp puts +EOS: + ret maxsect: .word 0 +reboot_msg: + .asciz "Disk error, press a key to reboot:" + +Boot_message: + .asciz "Boot sector loaded.\r\n" + ! Check for overlap end_of_code: if end_of_code>hitme |