nam Boot 8-bit LBA Mode Only!
ttl NitrOS-9 System Module
* Disassembled 94/06/25 11:37:47
by Alan DeKok
* ReDone by Paul T. Barton
99/08/17, for 8-bit IDE
*
* Uses only the low 8-bits
of each 16-bit sector.
*
Port
equ $FF70 still leaves room for SSPak & SSP & MPI
Status equ 0 Results
of read/write
CmdIde equ 0 Commands
DevHead equ 1 0,1,0,DEV,0,0,0,0
CylHigh equ 2
CylLow equ 3
SecNum equ 4
SecCnt equ 5 always
=1
ErrReg equ 6 Has
the errors
RData equ
7 data 0..7
WData equ
7 data 0..7
ReadCmd equ $20
Diagnos equ $90
BusyBit equ %10000000
BUSY=1
DrdyBit equ %01000000
drive ready=1
DscBit equ %00010000
seek finished=1
DrqBit equ %00001000
data requested=1
ErrBit equ %00000001
error_reg has it
RdyTrk equ %01010000
ready & over track
RdyDrq equ %01011000
ready w/ data
Master equ %01000000
LBA MODE
ifp1
use /dd/defs/os9defs
use /dd/defs/rbfdefs
use /dd/defs/6809defs
endc
tylg
set Systm+Obj6309
atrv
set ReEnt+rev
rev
set $02
mod eom,name,tylg,atrv,start,size
* on-stack buffer to use
org 0
size
equ .
name
equ *
fcs /Boot/
fcb $06
start orcc
#$50 ensure IRQ's are off.
pshs x,d save 4 bytes of
junk
R.D
equ 0
R.X
equ 2
clr >$FF40 stop the disk
lbsr Init
ldd #$0001 request one byte (will round
up to 1 page)
os9 F$SRqMem request the memory
bcs L00AE exit on error
* U is implicitely the buffer
address to use
ldx #$0000 X=0: got to sector #$0000
bsr GetSect load in LSN0, U = buffer start
bcs L00AE
lda #'0 --- loaded
in LSN0
jsr <D.BtBug ---
ldd <DD.BSZ,u size of the bootstrap file
std R.D,s save it on the stack
(0,s is junk)
ldx <DD.BT+1,u get starting sector of the bootstrap file
pshs x save
the starting sector number
ldd #256 one page of memory
os9 F$SRtMem return the copy of LSN0 to free memory
ldd R.X,s get size of boot memory
to request
os9 F$BtMem ask for the boot memory
puls x restore
the starting sector number
bcs L00AE no memory: exit with
error
stu R.X,s save start address
of memory allocated
ldd R.D,s and the size of the
boot memory
beq L00A7 if no memory allocated,
exit
SectLp
pshs x,d save sector #,
size of boot
bsr GetSect read one sector
bcs L00AC if there's an error,
exit
lda #'. dump out
a period for boot debugging
jsr <D.BtBug do the debug stuff
puls x,d restor sector,
size of boot
leau 256,u
leax 1,x go to the next
sector
subd #256 take out one sector,
need value in B, too.
bhi SectLp loop until all sectors are
read
L00A7 clrb
clear carry
puls d return
size of boot memory to user
bra L00B0 and go exit
L00AC leas
$04,s remove X,D off of stack
L00AE leas
$02,s kill D off of the stack
L00B0 puls
x restore start address
of memory allocated
*
leas size,s remove the on-stack buffer
L00BA rts
* GetSect: read a sector off
of the disk
* Entry: X = sector number
to read
* Memory: U = where to put
it
*
* Uses only the low 8-bits
of each 16-bit sector.
GetSect
pshs y
ldy <Address,pcr
grab the device address
bsr ChkBusy
RdyHuh1
lda Status,y
is IDE ready for commands?
anda #DrdyBit ready
?
beq RdyHuh1
loop until Drdy =1
lda #Master
sta DevHead,y 0L0d/0hhh
device=LBA
ldd #$0100
only one at a time
sta SecCnt,y
only one at a time
stb CylHigh,y bits
23-16
tfr x,d
sector number to read
sta CylLow,y
hi-byte
stb SecNum,y
leax ,u
where to put the sector
clrb
256-bytes counter
lda #ReadCmd
command to read one sector
sta CmdIde,y
finish process
Blk2
lda Status,y
is IDE ready to send?
anda #DrqBit
DRQ, data request
beq Blk2
loop while DRQ =0
BlkLp
lda RData,y
A <- IDE (8-bits only)
sta ,x+
into RAM
decb
256 each 8-bit xfers
bne BlkLp
go get the rest
lda Status,y
check for error-bit
clrb
puls y,pc
* ------------------------------------------
ChkBusy
lda Status,y
anda #BusyBit 1xxx-xxxx
bne ChkBusy
if =1 then loop
rts
exit when BUSY =0
Init
pshs d,y
ldy <Address,pcr
bsr ChkBusy
could be spinning up...
lda #Diagnos
hits all drives
sta CmdIde,y
./
bsr ChkBusy
wait 'til both done
clrb
no errors
puls d,y,pc
Address fdb
Port
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
fcb 0,1,2,3,4,5,6,7,8,9
emod
eom
equ *
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