c2d/asm/loader.s

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2017-04-09 00:41:29 +00:00
;diskload2.s
; apple vectors
warm = $FF69 ; back to monitor
bell = $FBDD ; ding
; vars
lopage = $0800
hipage = $B500
rwtsprm = $B7E8 ; looked at dos 3.3 disk, not using $3E3 to find
rwts = $B7B5
preg = $48 ; mon p reg
;trkcnt = $00 ; track counter
;segcnt = $01 ; loop var
;buffer = $02 ; MSB of RWTS buffer
;secnum = $03 ; loop var
;trknum = $04 ; loop var
start:
.org lopage
ldx #0 ; move code to hi memory
move:
lda moved,x
sta loader,x
inx
bne move ; move 256 bytes
jmp loader
moved:
.org hipage
loader:
lda #1 ; read(1)/write(2) command
ldy #$0C ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
lda #0 ; buffer LSB
ldy #8 ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
lda #2
sta trknum ; start with track 2
lda loadpage ; where to dump the tracks
sta buffer
ldx lasttrack
dex ; because data starts at track 2
dex
stx trkcnt ; number of complete and partial tracks
;;;begin track loop
trkloop:
lda trknum ; track number
ldy #4 ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
;;;begin sector loop (16), backwards is faster, much faster
lda trkcnt
bne fulltrack
lda lastsector
jmp subtrack
fulltrack:
lda #$F
subtrack:
sta secnum
secloop:
lda secnum ; sector number
ldy #5 ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
lda buffer ; buffer MSB
clc
adc secnum
ldy #9 ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
ldy #<rwtsprm ; load rwts paramlist B7E8
lda #>rwtsprm
jsr rwts ; do it!
bcs diskerror
lda #0
sta preg ; fix p reg so mon is happy
dec secnum
bpl secloop
;;;end sector loop
lda buffer ; buffer += $10
clc
adc #$10
sta buffer
inc trknum ; next track
dec trkcnt ;
bpl trkloop ; 0, all done with tracks
;;;end track loop
done:
jmp (nextjump)
diskerror:
jmp warm
lasttrack:
.org *+1
lastsector:
.org *+1
loadpage:
.org *+1
nextjump:
.org *+2
trkcnt:
.org *+1
segcnt:
.org *+1
buffer:
.org *+1
secnum:
.org *+1
trknum:
.org *+1