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NSC: More comments
This commit is contained in:
Joshua Bell
parent
95f029fc30
commit
6ee08e5c89
@ -1,6 +1,9 @@
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.setcpu "65C02"
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.setcpu "6502"
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.linecont +
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.include "apple2.inc"
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.include "opcodes.inc"
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;; ASCII
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BELL := $07
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CR := $0D
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@ -9,10 +12,7 @@ CR := $0D
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MAX_DW := $FFFF
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;; Softswitches
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KBD := $C000 ; Last Key Pressed + 128
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KBDSTRB := $C010 ; Keyboard Strobe
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CLR80VID := $C00C ; 40 Columns
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CLRALTCHAR := $C00E ; Primary Character Set
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ROMIN2 := $C082 ; Read ROM; no write
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RWRAM1 := $C08B ; Read/write RAM bank 1
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@ -21,6 +21,7 @@ PRODOS := $BF00
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DATETIME := $BF06
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DEVNUM := $BF30
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BITMAP := $BF58
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BITMAP_SIZE := 24 ; 24 bytes in bitmap
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DATELO := $BF90
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TIMELO := $BF92
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MACHID := $BF98
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@ -49,7 +50,7 @@ SETNORM := $FE84
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SETKBD := $FE89
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SETVID := $FE93
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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.macro PASCAL_STRING arg
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.byte .strlen(arg)
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@ -77,20 +78,20 @@ SETVID := $FE93
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.define HI(c) ((c)|$80)
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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data_buffer = $1800
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.define SYSTEM_SUFFIX ".SYSTEM"
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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.org $1000
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;; Loaded at $2000 but relocates to $1000
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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sys_start:
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sec
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@ -98,7 +99,7 @@ sys_start:
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.byte $04, $21, $91 ; 4/21/91
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Relocate this code from $2000 (.SYSTEM start location) to $1000
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;;; and start executing there. This is done so that the next .SYSTEM
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;;; file can be loaded/run at $2000.
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@ -122,7 +123,7 @@ load: lda src,y ; self-modified
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jmp load
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Identify the name of this SYS file, which should be present at
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;;; $280 with or without a path prefix. This is used when searching
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;;; for the next .SYSTEM file to execute.
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@ -156,7 +157,9 @@ cloop: iny
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.endproc
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;; Fall through...
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Before installing, get the system to a known state and
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;;; ensure there is not a previous clock driver installed.
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.proc pre_install
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cld
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@ -170,33 +173,38 @@ cloop: iny
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eor #$A5
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sta $03F4
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;; Quit 80-column firmware
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lda #$95 ; Ctrl+U (quit 80 col firmware)
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jsr COUT
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ldx #$FF ; Reset stack
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;; Reset stack
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ldx #$FF
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txs
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sta CLR80VID ; Reset I/O
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;; Reset I/O
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sta CLR80VID
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sta CLRALTCHAR
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jsr SETVID
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jsr SETKBD
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jsr SETNORM
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jsr INIT
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ldx #$17 ; Update system page bitmap
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lda #1
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;; Update System Bit Map
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ldx #BITMAP_SIZE-1
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lda #%00000001 ; protect page $BF
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: sta BITMAP,x
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lda #0
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lda #%00000000 ; nothing else protected until...
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dex
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bne :-
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lda #$CF
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lda #%11001111 ; ZP ($00), stack ($01), text page 1 ($04-$07)
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sta BITMAP
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lda MACHID
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and #$88 ; //e or //c ?
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and #$88 ; IIe or IIc (or IIgs) ?
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bne :+
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lda #$DF
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sta lowercase_mask ; lower case to upper case
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: lda MACHID
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and #$01 ; existing clock card?
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beq detect_nsc ; nope, check for NSC
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@ -208,7 +216,7 @@ cloop: iny
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jmp launch_next_sys_file
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Detect NSC. Scan slot ROMs and main ROMs. Try reading
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;;; each location several times, and validate results before
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;;; installing driver.
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@ -306,7 +314,7 @@ tries: .byte 3
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slot: .byte 0
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Install NSC Driver. Copy into address at DATETIME vector,
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;;; update the vector and update MACHID bits to signal a clock
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;;; is present.
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@ -317,7 +325,7 @@ slot: .byte 0
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lda DATETIME+1
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sta ptr
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clc
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adc #$73
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adc #(unlock - driver - 1)
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sta ld3+1
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lda DATETIME+2
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sta ptr+1
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@ -337,7 +345,7 @@ loop: lda driver,y
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ora #$01
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sta MACHID
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lda #$4C ; JMP opcode
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lda #OPC_JMP_abs
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sta DATETIME
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;; Invoke the driver to init the time
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@ -377,7 +385,7 @@ loop: lda driver,y
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jsr CROUT
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Find and invoke the next .SYSTEM file
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.proc launch_next_sys_file
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@ -523,7 +531,7 @@ not_found:
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jmp quit
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Output a high-ascii, null-terminated string.
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;;; String immediately follows the JSR.
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@ -555,7 +563,7 @@ skip: inc ptr
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rts
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; COUT a 2-digit number in A
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.proc cout_number
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@ -581,12 +589,13 @@ units: pla
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rts
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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lowercase_mask:
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.byte $FF ; Set to $DF on systems w/o lower-case
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Invoke ProDOS QUIT routine.
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.proc quit
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PRODOS_CALL MLI_QUIT, quit_params
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@ -601,7 +610,8 @@ lowercase_mask:
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.endproc
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Read a disk block.
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.proc read_block
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PRODOS_CALL MLI_READ_BLOCK, read_block_params
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@ -618,7 +628,7 @@ block_num: .word 2 ; block_num - block 2 is volume directory
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read_block_params_unit_num := read_block_params::unit_num
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read_block_params_block_num := read_block_params::block_num
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Load/execute the system file in PATHNAME
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.proc invoke_system_file
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@ -637,8 +647,8 @@ block_num: .word 2 ; block_num - block 2 is volume directory
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jmp SYS_ADDR ; Invoke loaded SYSTEM file
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.endproc
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;;; --------------------------------------------------
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;;; Error Handler
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;;; ------------------------------------------------------------
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;;; Error handler - invoked if any ProDOS error occurs.
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.proc on_error
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pha
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@ -655,7 +665,7 @@ block_num: .word 2 ; block_num - block 2 is volume directory
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jmp quit
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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.proc open_params
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.byte 3 ; param_count
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@ -679,7 +689,7 @@ ref_num:.byte 1 ; ref_num
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ref_num:.byte 0 ; ref_num
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.endproc
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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found_self_flag:
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.byte 0
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@ -689,8 +699,8 @@ suffix: .byte SYSTEM_SUFFIX
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self_name:
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PASCAL_STRING "NS.CLOCK.SYSTEM"
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;;; --------------------------------------------------
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;;; NSC driver - copied into ProDOS
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;;; ------------------------------------------------------------
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;;; NSC driver - modified as needed and copied into ProDOS
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driver:
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php
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@ -700,59 +710,74 @@ ld4: lda $CFFF ; self-modified
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st1: sta $C300 ; self-modified
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ld1: lda $C304 ; self-modified
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ldx #8
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L140D:
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;; Unlock the NSC by bit-banging.
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uloop:
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ld3: lda unlock-1,x ; self-modified
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sec
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ror a
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L1412: pha
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ror a ; a bit at a time
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: pha
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lda #0
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rol a
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tay
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ld2: lda $C300,y ; self-modified
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pla
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lsr a
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bne L1412
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bne :-
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dex
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bne L140D
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bne uloop
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;; Read 8 bytes * 8 bits of clock data into $200...$207
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ldx #8
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L1423: ldy #8
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bloop: ldy #8
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st2:
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: lda $C304 ; self-modified
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ror a
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ror $01FF,x
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dey
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bne :-
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lda $01FF,x
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lsr a
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lsr a
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lda $01FF,x ; got 8 bits
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lsr a ; BCD to binary
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lsr a ; shift out tens
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lsr a
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lsr a
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tay
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beq L1447
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beq donebcd
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lda $01FF,x
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and #$0F
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and #$0F ; mask out units
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clc
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: adc #$0A
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: adc #10 ; and add tens as needed
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dey
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bne :-
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sta $01FF,x
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L1447: dex
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bne L1423
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lda $0204
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donebcd:
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dex
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bne bloop
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;; Now $200...$207 is y/m/d/w/H/M/S/f
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;; Update ProDOS date/time.
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lda $0204 ; hour
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sta TIMELO+1
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lda $0205
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lda $0205 ; minute
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sta TIMELO
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lda $0201
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lda $0201 ; month
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asl a
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asl a
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asl a
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asl a
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asl a
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ora $0202
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ora $0202 ; day
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sta DATELO
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lda $0200
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lda $0200 ; year
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rol a
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sta DATELO+1
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pla
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bmi done
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st4: sta $CFFF ; self-modified
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@ -767,11 +792,11 @@ unlock:
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sizeof_driver := * - driver
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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sys_end:
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;;; --------------------------------------------------
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;;; ------------------------------------------------------------
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;;; Junk from here on...
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.byte $b3, $68, $72, $f0, $2a, $2a, $2a, $2a
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