84 lines
1.4 KiB
ArmAsm
84 lines
1.4 KiB
ArmAsm
ORG $C700
|
|
|
|
; Slot scan ZP addresses
|
|
SCAN_LO EQU $00
|
|
SCAN_HI EQU $01
|
|
|
|
; ProDOS
|
|
COMMAND EQU $42
|
|
UNIT EQU $43
|
|
ADDRESS_LO EQU $44
|
|
ADDRESS_HI EQU $45
|
|
BLOCK_LO EQU $46
|
|
BLOCK_HI EQU $47
|
|
|
|
MSLOT EQU $7F8
|
|
|
|
; Slot I/O addresses
|
|
STATUS EQU $C080
|
|
|
|
; ROM addresses
|
|
BASIC EQU $E000
|
|
SLOOP EQU $FABA ; Resume boot scan
|
|
ROMRTS EQU $FF58
|
|
BOOT EQU $0801
|
|
|
|
LDX #$20 ; $20 $00 $03 $00 - Smartport signature
|
|
LDX #$00 ; $20 $00 $03 $3C - Vanilla disk signature
|
|
LDX #$03
|
|
LDX #$00 ; Override with $3C for DumbPort
|
|
; Determine our slot
|
|
JSR ROMRTS
|
|
TSX
|
|
LDA $0100,X
|
|
STA MSLOT ; $Cn
|
|
ASL
|
|
ASL
|
|
ASL
|
|
ASL
|
|
TAY ; $n0
|
|
; Load the disk status bits
|
|
LDA STATUS,Y
|
|
LSR ; Check for Disk 1
|
|
BCS DISKREADY ; Boot from Disk 1
|
|
LDA SCAN_LO
|
|
BNE GO_BASIC
|
|
LDA SCAN_HI
|
|
CMP MSLOT
|
|
BNE GO_BASIC
|
|
JMP SLOOP ; Go back to scanning
|
|
GO_BASIC JMP BASIC ; Go to basic
|
|
; Boot routine
|
|
DISKREADY LDX #$01 ; Read
|
|
STX COMMAND
|
|
DEX
|
|
STX BLOCK_LO ; Block 0
|
|
STX BLOCK_HI
|
|
STX ADDRESS_LO ; Into $800
|
|
LDX #$08
|
|
STX ADDRESS_HI
|
|
LDA MSLOT
|
|
PHA ; Save slot address
|
|
PHA ; RTS address hi byte
|
|
LDA #REENTRY - 1
|
|
PHA ; RTS address lo byte
|
|
CLV
|
|
BVC BLOCK_ENT
|
|
REENTRY PLA ; Restore slot address
|
|
ASL ; Make I/O register index
|
|
ASL
|
|
ASL
|
|
ASL
|
|
TAX
|
|
JMP BOOT
|
|
DS 2
|
|
BLOCK_ENT RTS
|
|
DS 2
|
|
SMARTPOINT_ENT RTS
|
|
PADDING DS $C7FE - PADDING
|
|
ORG $C7FE
|
|
FLAGS DFB $D7
|
|
ENTRY_LO DFB BLOCK_ENT
|
|
|
|
END
|