A2osX/ProDOS.FX/ProDOS.S.RAM.txt
2019-11-04 08:21:40 +01:00

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NEW
AUTO 3,1
RAM.START
RAMDRV cld no decimal.
ldx #$0B save 13 bytes of parms
.1 lda A1L,x
sta a1l1,x
dex
bpl .1
ldx #$01
.2 lda passit,x save xfer vectors
sta sp1,x
dex
bpl .2
lda A4L get command.
beq stat 0 = status
cmp #$04 check for command too high.
bcs ioerr if it is, i/o error
eor #$03
sta A4L 0=format, 2=read, 1=write
beq format
ldy bloknml+1 check for large block number.
bne ioerr too big.
lda bloknml block #
bmi ioerr largest block number is $7F
* at this point, control is passed to the code in the alternate 64k.
* it it used for read, write and format. after the request is completed,
* control is passed back to 'noerr'.
format lda #RAMXDRV card entry point
sta passit
lda /RAMXDRV
gocard sta passit+1 also used by 'mainwrt'
sec direction ram -> card
clv start with original zero page
jmp xfer transfer control
ioerr lda #$27
bne H2D41
lda #$2B write protect error.
H2D41 sec flags error
bcs H2D47
noerr .EQ *
stat lda #$00
clc
H2D47 php save status
pha and error code.
ldx #$0B restore 13 byes of parms
H2D4B lda a1l1,x
sta A1L,x
dex
bpl H2D4B
lda sp1 restore xfer parms.
bit $6060 addr $FF58 must = rts ($60) as in ROM
sta passit
lda sp1+1
sta passit+1
pla restore error code
plp and status.
rts
mainwrt sta SETWRITEAUX write to alt 48K
ldy #$00
H2D6A lda (A1L),y pointers set in card by 'setptr'
sta (A4L),y
lda (A2L),y
sta (A3L),y
dey
bne H2D6A
sta CLRWRITEAUX write to main 48K.
lda #donewrt done writing card
sta passit
lda /donewrt
jmp gocard
sp1 .HS 0000
a1l1 .BS 13 13 bytes of storage
*--------------------------------------
RAM.LEN .EQ *-RAM.START
MAN
SAVE USR/SRC/PRODOS.FX/PRODOS.S.RAM
LOAD USR/SRC/PRODOS.FX/PRODOS.S
ASM