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Indent boot sector
This commit is contained in:
Michaelangel007
parent
17838e2515
commit
011a85d922
325
README.md
325
README.md
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@ -205,199 +205,204 @@ Now I could be a jerk and hand-wave it as
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but I'll be nice guy and provide a fully documented disassembly:
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```asm
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; P5 PROM Drive Usage ZP and IO
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P5.Buff = $26 ; 16-bit pointer to dest
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P5.SlotX16 = $2B ; i.e. $60 = Slot 6
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P5.WantTrack= $41 ;
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; Disk Drive P5 PROM Usage ZP and IO
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P5.Buff = $26 ; 16-bit pointer to dest
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P5.SlotX16 = $2B ; i.e. $60 = Slot 6
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P5.WantTrack = $41 ;
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P5.SecLoaded= $3D ;
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P5.SecTotal = $0800 ; Boot Sector contains total number of sectors to load
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P5.SecWant = $3D ;
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P5.SecTotal = $0800 ; T00S0 @ $00: total number of sectors to load
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PHASEMSAK = $03 ; 4 phases
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PHASEOFF = $C080
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PHASEON = $C081
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DRIVE_DATA = $C08C
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PHASE_MASK = $03 ; 4 phases
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PHASE0_OFF = $C080
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PHASE0_ON = $C081
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; Globals
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SEEK_HALFTRACK = $50
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HAVE_HALFTRACK = $51
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NumSecLeft = $52
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BufZP = $1000 ; Zero Page is saved here
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DRIVE_OFF = $C088 ; Motor Off
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DRIVE_ON = $C089 ; Motor On
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DRIVE_DATA = $C08C
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RWTS_SLOTx16 = $FD
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RWTS_HALFTRACK = $FF ;
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; Globals
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boot_HalfTrack_Seek = $50
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boot_HalfTrack_Have = $51
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NumSecLeft = $52
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BufZP = $1000 ; Zero Page is saved here
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ReadBoot3 = $B500
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LoadBoot3 = $BC00
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ExecBoot3 = $BE00
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rwts_SlotX16 = $FD
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rwts_HalfTrack_Have = $FF ;
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; Misc.
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RESET = $3F2 ; Ctrl-Reset Vector + Checksum
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TXTHOLE31 = $4FB ; 40x24 Text Sceen Hole
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ReadBoot3 = $B500
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LoadBoot3 = $BC00
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ExecBoot3 = $BE00
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; IO Switches
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STORE40 = $C000 ; W
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ALTZPOFF = $C008
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CLR80VID = $C00C
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CLRALTCHAR = $C00E ; Turn off Mouse Text
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DHIRESOFF = $C05F
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; Misc.
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RESET = $3F2 ; Ctrl-Reset Vector + Checksum
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TXTHOLE31 = $4FB ; 40x24 Text Sceen Hole
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ROMIN = $C081
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; IO Switches
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STORE40 = $C000 ; W
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KEYBOARD = $C000 ;R
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KEYSTROBE = $C010
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ALTZPOFF = $C008
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CLR80VID = $C00C
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CLRALTCHAR = $C00E ; Turn off Mouse Text
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DHIRESOFF = $C05F
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; F800 ROM Entry Points
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F8.INIT = $FB2F ;
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F8.HOME = $FC58 ; Clear 40x24 text screen
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F8.SETNORM = $FE84 ;
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F8.SETVID = $FE93 ; PR#0
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F8.SETKBD = $FE89 ; IN#0
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ROMIN = $C081
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ORG $800
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; F800 ROM Entry Points
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F8.INIT = $FB2F ;
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F8.HOME = $FC58 ; Clear 40x24 text screen
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F8.SETNORM = $FE84 ;
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F8.SETVID = $FE93 ; PR#0
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F8.SETKBD = $FE89 ; IN#0
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0800:01 DFB $01 ; Tell P5 PROM to read only 1 Sector
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Boot1: ; A=01 X=60 Y=00 P=31 S=F0 Boot Stage #1 Entry Point from $C6F8
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0801:A9 60 LDA #$60 ; Save "RTS" @ $0801 so that when we call
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0803:8D 01 08 STA Boot1 ; `CallReadSec` it will return to NextSector @ $086F
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ORG $800
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0806:A2 00 LDX #$00 ; Save _absolute_ track the drive head is on
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0808:86 FF STX RWTS_HALFTRACK ; since we can only move _relative_ tracks
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0800:01 DFB $01 ; Tell P5 PROM to read only 1 Sector
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Boot1: ; A=01 X=60 Y=00 P=31 S=F0 Boot Stage #1 Entry Point from $C6F8
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0801:A9 60 LDA #$60 ; Poke "RTS" @ $0801 so that when we call
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0803:8D 01 08 STA Boot1 ; `CallReadSec` it will return to NextSector @ $086F
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080A: SaveZP: ; Copy $0000[ $00 .. $FF ] to $1000
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080A:B5 00 LDA $00,X ; Just in case ALTZPON was accidently left on
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080C:9D 00 10 STA BufZP,X ;
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080F:E8 INX ;
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0810:D0 F8 BNE SaveZP ;^ $080A
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0806:A2 00 LDX #$00 ; Save _absolute_ track the drive head is on
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0808:86 FF STX rwts_HalfTrack_Have ; since we can only move _relative_ tracks
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0812:8D 08 C0 STA ALTZPOFF ; //e+, //c, IIgs, Laser 128
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080A: SaveZP: ; Copy $0000[ $00 .. $FF ] to $1000
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080A:B5 00 LDA $00,X ; Just in case ALTZPON was accidently left on
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080C:9D 00 10 STA BufZP,X ;
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080F:E8 INX ;
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0810:D0 F8 BNE SaveZP ;^ $080A
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LoadZP: ;
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0815:BD 00 10 LDA BufZP,X ;
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0818:95 00 STA $00,X ;
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081A:E8 INX ;
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081B:D0 F8 BNE LoadZP ;^ $0815
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0812:8D 08 C0 STA ALTZPOFF ; //e+, //c, IIgs, Laser 128
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081D:A9 FF LDA #$FF ;
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081F:8D FB 04 STA TXTHOLE31 ; Screen Text Hole Slot 3, Temp 1
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LoadZP: ;
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0815:BD 00 10 LDA BufZP,X ;
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0818:95 00 STA $00,X ;
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081A:E8 INX ;
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081B:D0 F8 BNE LoadZP ;^ $0815
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0822:8D F3 03 STA RESET+1 ; Make Ctrl-Reset
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0825:8D F4 03 STA RESET+2 ; do warm restart @ TODO: FIXME:
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081D:A9 FF LDA #$FF ;
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081F:8D FB 04 STA TXTHOLE31 ; Screen Text Hole Slot 3, Temp 1
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0828:8D 00 C0 STA STORE40 ;
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082B:8D 0C C0 STA CLR80VID ;
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082E:8D 0E C0 STA CLRALTCHAR ;
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0831:8D 5F C0 STA DHIRESOFF ;
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0834:8D 81 C0 STA ROMIN ;
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0822:8D F3 03 STA RESET+1 ; Make Ctrl-Reset
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0825:8D F4 03 STA RESET+2 ; do warm restart @ TODO: FIXME:
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0837:20 2F FB JSR F8.INIT ;
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083A:20 58 FC JSR F8.HOME ; Clear 40x24 text screen
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083D:20 84 FE JSR F8.SETNORM ;
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0840:20 93 FE JSR F8.SETVID ; PR#0
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0843:20 89 FE JSR F8.SETKBD ; IN#0
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0828:8D 00 C0 STA STORE40 ;
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082B:8D 0C C0 STA CLR80VID ;
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082E:8D 0E C0 STA CLRALTCHAR ;
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0831:8D 5F C0 STA DHIRESOFF ;
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0834:8D 81 C0 STA ROMIN ;
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0846:A6 2B LDX P5SLOTx16 ; X=60 = Drive Slot * $10
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0848:8A TXA ;
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0849:4A LSR ;
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084A:4A LSR ;
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084B:4A LSR ;
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084C:4A LSR ; A=06
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084D:09 C0 ORA #$C0 ; A=C6 = $Cx00 = Memory-Mapped IO: i.e. $C6 = slot 6 P5 PROM
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084F:8D 6E 08 STA CallReadSec+2 ; *** SELF-MODIFYING Code !
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0837:20 2F FB JSR F8.INIT ;
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083A:20 58 FC JSR F8.HOME ; Clear 40x24 text screen
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083D:20 84 FE JSR F8.SETNORM ;
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0840:20 93 FE JSR F8.SETVID ; PR#0
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0843:20 89 FE JSR F8.SETKBD ; IN#0
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0852:A9 0F LDA #$0F ; Num Sectors to Read
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0854:85 52 STA NumSecLeft ;
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0856:A9 15 LDA #$15 ; Track $15 contains Boot Stage 2
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0858:85 41 STA P5.WantTrack ;
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085A:0A ASL ; $15 * 2 = $2A Half-Tracks
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085B:20 81 08 JSR HalfTrackSeek ;v $0881
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0846:A6 2B LDX P5SLOTx16 ; X=60 = Drive Slot * $10
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0848:8A TXA ;
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0849:4A LSR ;
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084A:4A LSR ;
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084B:4A LSR ;
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084C:4A LSR ; A=06
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084D:09 C0 ORA #$C0 ; A=C6 = $Cx00 = Memory-Mapped IO: i.e. $C6 = slot 6 P5 PROM
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084F:8D 6E 08 STA CallReadSec+2 ; *** SELF-MODIFYING Code !
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LoadSector:
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085E:A5 52 LDY NumSecLeft ;
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0860:B9 BE 08 LDA LogicalSector,Y ;
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0863:85 3D STA P5SECTOR ;
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0865:B9 CE 08 LDA DestPage,Y ;
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0868:F0 05 BEQ NextSector ;v $086F Never read into Zero Page!
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086A:85 27 STA P5.Buff+1 ; Tell P5PROM where in mem we want to load
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0852:A9 0F LDA #$0F ; Num Sectors to Read
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0854:85 52 STA NumSecLeft ;
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0856:A9 15 LDA #$15 ; Track $15 contains Boot Stage 2
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0858:85 41 STA P5.WantTrack ;
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085A:0A ASL ; $15 * 2 = $2A Half-Tracks
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085B:20 81 08 JSR BS.HalfTrackSeek ;v $0881
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CallReadSec: ; *** SELF-MODIFIED @ $084F
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086C:20 5C 00 JSR $005C ; CALL P5 PROM Read Sector @ $C65C
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LoadSector:
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085E:A5 52 LDY NumSecLeft ;
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0860:B9 BE 08 LDA LogicalSector,Y ;
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0863:85 3D STA P5.SecWant ;
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0865:B9 CE 08 LDA DestPage,Y ;
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0868:F0 05 BEQ NextSector ;v $086F Never read into Zero Page!
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086A:85 27 STA P5.Buff+1 ; Tell P5 PROM where in mem we want to load
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NextSector:
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086F:C6 52 DEC NumSecLeft ;
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0871:10 EB BPL LoadSector ;^ $085E
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CallReadSec: ; *** SELF-MODIFIED @ $084F
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086C:20 5C 00 JSR $005C ; CALL P5 PROM Read Sector @ $C65C
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TestBoot3: ; Boot Stage 2 done, do stage 3
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0873:A6 2B LDX P5.SlotX16 ;
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0875:86 FD STX RWTS_SLOTx16 ;
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0877:A9 BC LDA #>LoadBoot3 ; Load T$22 4&4 "4 sectors" @ $BC00, $BD00, $BE00, $BF00
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0879:20 00 B5 JSR ReadBoot3 ; Boot Stage 2 reads in encrypted Stage 3
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087C:B0 F5 BCS TestBoot3 ;^ $0873 C=1 error, Hang if NibbleCheck1 fails
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087E:4C 00 BE JMP ExecBoot3 ;
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NextSector:
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086F:C6 52 DEC NumSecLeft ;
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0871:10 EB BPL LoadSector ;^ $085E
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HalfTrackSeek: ; A = Half Track to Seek
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0881:85 50 STA SEEK_HALFTRACK ; Save Half Track to seek
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TestBoot3: ; Boot Stage 2 done, do stage 3
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0873:A6 2B LDX P5.SlotX16 ;
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0875:86 FD STX rwts_SlotX16 ;
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0877:A9 BC LDA #>LoadBoot3 ; Load T$22 4&4 "4 sectors" @ $BC00, $BD00, $BE00, $BF00
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0879:20 00 B5 JSR ReadBoot3 ; Boot Stage 2 reads in encrypted Stage 3
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087C:B0 F5 BCS TestBoot3 ;^ $0873 C=1 error, Hang if NibbleCheck1 fails
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087E:4C 00 BE JMP ExecBoot3 ;
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NextTrack: ;
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0883:A5 FF LDA RWTS_HALFTRACK ; 6502 Math Reminder:
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0885:85 51 STA HAVE_HALFTRACK ; Clear Carry before Addition
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0887:38 SEC ; Set Carry before Subtraction
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0888:E5 50 SBC SEEK_HALFTRACK ; Already on requested track?
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088A:F0 2C BEQ SeekDone ;v $08B8 Yup! Nothing to do!
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088C:B0 04 BCS MoveTrackOut ;v $0892 Move Track out to Track $00
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BS.HalfTrackSeek: ; A = Half Track to Seek
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0881:85 50 STA boot_HalfTrack_Seek ; Save Half Track to seek
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MoveTrackIn:
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088E:E6 FF INC RWTS_HALFTRACK ; Move Track in to Track $22
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0890:90 02 BCC DoSeek ;v $0894 Always, could also do: INC RWTS_HALFTRACK
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BS.NextTrack: ;
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0883:A5 FF LDA rwts_HalfTrack_Have ; 6502 Math Reminder:
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0885:85 51 STA boot_HalfTrack_Have ; Clear Carry before Addition
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0887:38 SEC ; Set Carry before Subtraction
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0888:E5 50 SBC boot_HalfTrack_Seek ; Already on requested track?
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088A:F0 2C BEQ SeekDone ;v $08B8 Yup! Nothing to do!
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088C:B0 04 BCS BS.MoveTrackOut ;v $0892 Move Track out to Track $00
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MoveTrackOut:
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0892:C6 FF DEC RWTS_HALFTRACK ; Intentional fall-into DoSeek
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BS.MoveTrackIn:
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088E:E6 FF INC rwts_HalfTrack_Have ; Move Track in to Track $22
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0890:90 02 BCC DoSeek ;v $0894 Always, could also do: INC rwts_HalfTrack_Have
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DoSeek: ; Common code
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0894:20 AD 08 JSR PhaseOn ;v
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0897:20 B9 08 JSR Delay ;v
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PhaseOff:
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089A:A5 51 LDA HAVE_HALFTRACK ;
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089C:29 03 AND #PHASEMASK ; Drive Stepper Motor = 4 Phases
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089E:0A ASL ; 1 phase = 1/2 track
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089F:05 2B ORA P5.SlotX16 ;
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08A1:A8 TAY ;
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08A2:B9 80 C0 LDA PHASEOFF,Y ; Turn stepper motor off
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08A5:20 B9 08 JSR Delay ;v
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08A8:F0 D9 BEQ NextTrack ;^ $0883 A=00, always
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08AA:20 B9 08 JSR Delay ;v *** DEAD CODE ??? Never reached!
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PhaseOn:
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08AD:A5 FF LDA RWTS_HALFTRACK ;
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08AF:29 03 AND #PHASEMASK ;
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08B1:0A ASL ; 1 phase = 1/2 track
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08B2:05 2B ORA P5.SlotX16 ;
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08B4:A8 TAY ;
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08B5:B9 81 C0 LDA PHASEON,Y ; Turn stepper motor on
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SeekDone:
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08B8:60 RTS ;
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Delay:
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08B9:A9 28 LDA #$28 ; You _could_ minimize the delay time like in DOS 3.3
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08BB:4C A8 FC JMP WAIT ; but that bloats the code
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BS.MoveTrackOut:
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0892:C6 FF DEC rwts_HalfTrack_Have ; Intentional fall-into DoSeek
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LogicalSector: ; Logical->Phystical Sector = Interleave 2
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DoSeek: ; Boot Sector Common code
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0894:20 AD 08 JSR BS.PhaseOn ;v
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0897:20 B9 08 JSR BS.Delay ;v
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BS.PhaseOff:
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089A:A5 51 LDA boot_HalfTrack_Have ;
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089C:29 03 AND #PHASE_MASK ; Drive Stepper Motor = 4 Phases
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089E:0A ASL ; 1 phase = 1/2 track
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089F:05 2B ORA P5.SlotX16 ;
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08A1:A8 TAY ;
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08A2:B9 80 C0 LDA PHASE0_OFF,Y ; Turn stepper motor off
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08A5:20 B9 08 JSR BS.Delay ;v
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08A8:F0 D9 BEQ BS.NextTrack ;^ $0883 A=00, always
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08AA:20 B9 08 JSR BS.Delay ;v *** DEAD CODE ??? Never reached!
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BS.PhaseOn:
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08AD:A5 FF LDA rwts_HalfTrack_Have ;
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08AF:29 03 AND #PHASE_MASK ;
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08B1:0A ASL ; 1 phase = 1/2 track
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08B2:05 2B ORA P5.SlotX16 ;
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08B4:A8 TAY ;
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08B5:B9 81 C0 LDA PHASE0_ON,Y ; Turn stepper motor on
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SeekDone:
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08B8:60 RTS ;
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BS.Delay:
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||||
08B9:A9 28 LDA #$28 ; You _could_ minimize the delay time like in DOS 3.3
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08BB:4C A8 FC JMP WAIT ; but that bloats the code
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08BE:00 0D 0B 09 DFB $00,$0D,$0B,$09,$07,$05,$03,$01
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08C2:07 05 03 01
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08C6:0E 0C 0A 08 DFB $0E,$0C,$0A,$08,$06,$04,$02,$0F
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||||
08CA:06 04 02 0F
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LogicalSector: ; Logical->Physical Sector = Interleave 2, DOS order?? TODO
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DestPage:
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08CE:B0 B1 B2 B3 DFB $B0,$B1,$B2,$B3,$B4,$B5,$B6,$B7 ; "Pages" of 16-bit address
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08D2:B4 B5 B6 B7
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08D6:18 19 1A 1B DFB $18,$19,$1A,$1B,$1C,$1D,$1E,$1F ; to load into
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08DA:1C 1D 1E 1F
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DS $900-* ; unused/wasted
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08DE:00 00 ;
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08E0:00 00 00 00 ;
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08E4:00 00 00 00 ;
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||||
08E8:00 00 00 00 ;
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08EC:00 00 00 00 ;
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08F0:00 00 00 00 ;
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08F4:00 00 00 00 ;
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08F8:00 00 00 00 ;
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08FC:00 00 00 00 ;
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08BE:00 0D 0B 09 DFB $0,$D,$B,$9,$7,$5,$3,$1
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||||
08C2:07 05 03 01
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08C6:0E 0C 0A 08 DFB $E,$C,$A,$8,$6,$4,$2,$F
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08CA:06 04 02 0F
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||||
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DestPage:
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08CE:B0 B1 B2 B3 DFB $B0,$B1,$B2,$B3,$B4,$B5,$B6,$B7 ; "Pages" of 16-bit address
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||||
08D2:B4 B5 B6 B7
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||||
08D6:18 19 1A 1B DFB $18,$19,$1A,$1B,$1C,$1D,$1E,$1F ; to load into
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08DA:1C 1D 1E 1F
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DS $900-* ; unused/wasted
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08DE:00 00 ;
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||||
08E0:00 00 00 00 ;
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||||
08E4:00 00 00 00 ;
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08E8:00 00 00 00 ;
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08EC:00 00 00 00 ;
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||||
08F0:00 00 00 00 ;
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08F4:00 00 00 00 ;
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||||
08F8:00 00 00 00 ;
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||||
08FC:00 00 00 00 ;
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```
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## P5 Boot PROM
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Block a user