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Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 86/CONCURRENT/CCPM-86 3.1 SOURCE/D4/XFLOPPY.LIB
Sepp J Morris 31738079c4 Upload 
Digital Research
2020-11-06 18:50:37 +01:00

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eject ; Dec 9, 1983
; DISK I/O
; --------
;****************************************************************
;* *
;* FLOPPY DISK DRIVER EQUATES *
;* *
;****************************************************************
; The following equates are set to the size of a double density,
; single sided 5 & 1/4" floppy.
bytes_per_sector equ 512
sectors_per_track equ 8 ;1 to 8
bytes_per_track equ sectors_per_track * bytes_per_sector
; The following equates are for the INTEL 8272 Floppy Disk
; Controller.
fdc_stat equ 03f4h ;status port for disk controller
fdc_data equ fdc_stat+1 ;data port for disk controller
fdc_port equ 03f2h ;all bits clear on channel reset
;7 6 5 4 3 2 1 0
;| | | | | | \_/
;| | | | | | |
;| | | | | | drive select 00=a,01=b,10=c,11=d
;| | | | | fdc reset*
;| | | | int & dmarq enable
;d c b a motor on
fdc_on equ 00001100b ;mask to keep the 8272 unreset
fdc_reset_bit equ 00000100b ;8272 reset when low
fdc_no_motor equ 11111100b ;mask for no motors
fdc_cmnd_read equ 01100110b ;mfm, skip deleted data, read
fdc_cmnd_write equ 01000101b ;mfm, write
fdc_cmnd_format equ 01001101b ;mfm, format
fdc_cmnd_seek equ 00001111b ;seek
fdc_cmnd_recal equ 00000111b ;home to track 0
fdc_cmnd_si equ 00001000b ;sense interupt status
fdc_cmnd_spec equ 00000011b ;specify
fdc_ready_write equ 10000000b ;mask for transfer ready
fdc_ready_read equ 10000000b ;mask for transfer ready
fdc_spec_1 equ 11001111b ;srt=0c, hd unload=0f 1st specify byte
fdc_spec_2 equ 00000010b ;hd load=1, mode=dma 2nd specify byte
f_bytes equ 2 ;magic number for 512 bytes per sector
f_sectors equ 8 ;sectors per track
f_gap equ 050h ;this is IBM's, not August's
f_filler equ 0e5h ;fill character
r_bytes equ 2 ;magic number for 512 bytes
r_sectors equ 8
r_gap equ 02ah
r_dtl equ 0ffh
; Equates for paramter passing for read and write from BDOS.
; At the disk read and write function entries,
; all disk I/O parameters are on the stack.
; The stack at these entries appears as follows:
; +-------+-------+
; +14 | DRV | MCNT | Drive and Multi sector count
; +-------+-------+
; +12 | TRACK | Track number
; +-------+-------+
; +10 | SECTOR | Physical sector number
; +-------+-------+
; +8 | DMA_SEG | DMA segment
; +-------+-------+
; +6 | DMA_OFF | DMA offset
; +-------+-------+
; +4 | RET_SEG | BDOS return segment
; +-------+-------+
; +2 | RET_OFF | BDOS return offset
; +-------+-------+
; SP+0 | RET_ADR | Return address to XIOS ENTRY routine
; +-------+-------+
;
; These parameters may be indexed and modifided
; directly on the stack by the XIOS read and write rotines
; They will be removed by the BDOS when the XIOS completes
; the read/write function and returns to the BDOS.
drive equ byte ptr 14[bp]
mcnt equ byte ptr 15[bp]
track equ word ptr 12[bp]
sector equ word ptr 10[bp]
dma_seg equ word ptr 8[bp]
dma_off equ word ptr 6[bp]
; Some equates in the Disk Parameter Header (DPH)
; and the Disk Parameter Block.
xlt equ 0 ;translation table offset in DPH
dpb equ 8 ;disk parameter block offset in DPH
spt equ 0 ;sectors per track offset in DPB
psh equ 15 ;physical shift factor offset in DPB
;****************************************************************
;* *
;* 8237 DIRECT MEMORY ACCESS CONTROLLER PORT AND COMMANDS *
;* *
;****************************************************************
dma_c2_address equ 004h ;8237 channel 2 address rw
dma_c2_count equ 005h ;8237 channel 2 transfer count rw
dma_stat_reg equ 008h ;8237 status register ro
dma_bmsk_reg equ dma_stat_reg+2 ;8237 binary channel mask wo
dma_mode_reg equ dma_stat_reg+3 ;8237 mode register wo
dma_cbpf equ dma_stat_reg+4 ;8237 clear byte ptr f/f wo
dma_page_fdc equ 081h ;a16 to a20 for channel 2
; The following labels define single mode, address increment
; auto-initialization disable, read or write using channel 2
dma_mode_write_fdc equ 01001010b
dma_mode_read_fdc equ 01000110b
dma_mode_verify_fdc equ 01000010b
dma_bmsk_fdc equ 00000010b ;binary channel mask for disk
; DMA channel assignments
;channel 0 dynamic memory refresh
;channel 1
;channel 2 floppy disk controller
;channel 3
;********************************************************
;* *
;* DISK DRIVER ROUTINES *
;* *
;********************************************************
reorg12 equ offset $
cseg
org reorg12
; Function 7: Select Disk
; entry: CL = disk to be selected
; DL = 00h if disk has not been previously selected
; = 01h if disk has been previously selected
; exit: AX = 0 if illegal disk
; = offset of DPH relative from
; XIOS Data Segment
io_seldsk:
mov bx,offset select_tbl
jmps disk_branch ; vector to select routine
; Function 11: Read sector
; Reads the sector on the current disk, track and
; sector into the current dma buffer.
; entry: parameters on stack
; exit: AL = 00 if no error occured
; AL = 01 if an error occured
io_read:
mov bx,offset read_tbl
jmps io_rw ; code shared with io_write
; Function 12: Write disk
; Write the sector in the current Dma buffer to the current disk
; on the current track in the current sector.
; exit: Al = 00H if no error occured
; = 01H if error occured
; = 02H if read only disk
io_write:
mov bx,offset write_tbl
io_rw:
mov bp,sp ; for stack parameters
mov cl,drive ; for branching out
mov cur_disk,cl ; save for port stuff
; jmps disk_branch
; Branch point for select, read, and write
; entry: bx -> routine vector base
; cl = disk number
disk_branch:
mov ch,0 ; clear msb
mov si,cx
shl si,1 ; si = disk number index
jmp word ptr [bx+si]
; Select Disk branch table
select_tbl dw select_flop,select_flop ; A,B
dw select_flop,select_flop ; C,D
dw select_hd,select_hd ; E,F
dw sel_fid,sel_fid,sel_fid ; G,H,I
dw sel_fid,sel_fid,sel_fid ; J,K,L
dw select_mdisk,sel_fid,sel_fid ; M,N,O
dw sel_fid ; P
; Read branch table
read_tbl dw read_flop,read_flop ; A,B
dw read_flop,read_flop ; C,D
dw read_hd,read_hd ; E,F
dw read_fid,read_fid,read_fid ; G,H,I
dw read_fid,read_fid,read_fid ; J,K,L
dw read_mdisk,read_fid,read_fid ; M,N,O
dw read_fid ; P
; Write branch table
write_tbl dw write_flop,write_flop ; A,B
dw write_flop,write_flop ; C,D
dw write_hd,write_hd ; E,F
dw write_fid,write_fid,write_fid ; G,H,I
dw write_fid,write_fid,write_fid ; J,K,L
dw write_mdisk,write_fid,write_fid ; M,N,O
dw write_fid ; P
; Function 12: Flush buffers
; This is a nop nowadays
io_flushbuf:
xor al,al ; zero for no error
ret
; Function 15: Format floppy disk
; Format the current track of the current drive
; exit: al = 00h if no error
; al > 00h if error occured
io_format:
mov bp,sp ; for stack parameters
jmp format_floppy ; down in the code
; *** Floppy Disk Subroutines ***
; Select floppy disk, check size if first time
; entry: cl = drive number
select_flop:
mov bx,dph_tbl[si] ; fetch dph pointer
cmp dl,0 ; if not first time selected
jnz sel_flop1 ; then skip
push cx
mov al,0FEh ; lsb off
shl al,cl ; move off bit to disk number
and recal_byte,al ; this drive not recal'd
pop cx
call floppy_size ; double or single sided
sel_flop1:
mov ax,bx ; return dph in ax
ret
; Read floppy track 0 sector 0 into the local buffer
; to decide whether it's single or double sided.
; entry: bx = dph pointer
; cl = drive code
; exit: bx = dph pointer or 00h if error reading size
floppy_size:
push bx ; save dph pointer
mov al,cl ; drive code
mov ah,1 ; multi-sector count
push ax ; stack drive,mcnt
sub ax,ax
push ax ; stack track
push ax ; stack sector
push ds ; stack dma segment
mov ax,offset local_buffer
push ax ; stack dma offset
sub sp,4 ; skip the far return
call io_read ; read the sector
add sp,14 ; clear the stack
pop bx ; restore dph pointer
test al,al ; if an error comes back
jnz flop_size_bad ; then return zero
mov ax,offset dpbs ; assume single sided
cmp floppy_type,01h ; if not double sided
jnz flop_size1 ; then skip
mov ax,offset dpbd ; set to double sided
flop_size1:
mov .dpb[bx],ax ; save dpb offset in dph
ret
flop_size_bad:
sub bx,bx ; return bx=00h
ret
; Floppy Disk sector Read entry
read_flop:
mov dma_mode_storage,dma_mode_read_fdc
mov fdc_command,fdc_cmnd_read ;set up the command words
jmp flp_io
; Floppy Disk sector Write entry
write_flop:
mov dma_mode_storage,dma_mode_write_fdc
mov fdc_command,fdc_cmnd_write
call flp_io
test al,al ; check return code
jnz write_flop_done ; if bad, give up
cmp verify_flag,0 ; if we aren't verifying
jz write_flop_done ; then we're also done
mov dma_mode_storage,dma_mode_verify_fdc
mov fdc_command,fdc_cmnd_read
call flp_io
write_flop_done:
ret ; with code in al
; Floppy Disk track Format entry
format_floppy:
mov dma_mode_storage,dma_mode_write_fdc
mov fdc_command,fdc_cmnd_format
mov ax,ds ; local dma buffer for c,h,r,n
mov bx,offset format_block
call comp_dma ; set up dma pointers
mov al,drive ; current drive (on stack)
mov cur_disk,al ; save for seek
mov ax,track ; also on stack
mov cur_trk,ax
call disk_init ; this does it
call check_disk_op ; did it work?
cmp al,'R' ; if retry requested
jz format_floppy ; then loop up
ret ; else return error code
; Common code for floppy read and write
flp_io:
;note: SECTOR, TRACK is 0 relative
;MCNT, SECTORS_PER_TRACK are relative to 1
mov ax,sectors_per_track;max sectors - starting sector =
sub ax,sector ;sectors left on track
xor bh,bh
mov bl,mcnt ;multi sector count is byte variable
cmp ax,bx ;sectors left on track, sectors requested
jbe flp_track ;transfer to end of track
mov al,mcnt ;transfer to before end of track
flp_track:
sub mcnt,al ;AL = # sectors to r/w on this iteration
;through FLP_IO,
mov track_mcnt,al ;sectors to r/w on current track
;check for 64K page overlap
mov ah,al ;shl al,8 (* 256)
xor al,al
shl ah,1 ;* 512
push ax ;how many bytes to r/w on cur trk
mov ax,dma_seg ;compute new 20 bit DMA addr
mov bx,dma_off
call comp_dma ;returns AX = low 16 bits of 20 bit adr
not ax ;how many bytes left in this 64K page
pop bx
cmp ax,bx ;does this transfer fit in 64K page
jae flp_pg_ok ;yes
call flp_deblock ;do a local read/write
jnz flp_ret
mov ax,dma_seg ;compute new 20 bit DMA addr
mov bx,dma_off
call comp_dma
flp_pg_ok: ;read will not cross 64K boundary
mov al,track_mcnt ;could be 0 if we just deblocked
test al,al ! jz nxt_track
mov num_sec,al ;read the rest from this track
call floppy_io ;DMA is already computed
jnz flp_ret ;return error if zero flag is not set
xor ax,ax
mov ah,num_sec ;shl num_sec,8 (* 256)
shl ah,1 ;* 512
add dma_off,ax
nxt_track:
xor al,al
cmp mcnt,al
jz flp_ret
inc track
mov sector,0
jmp flp_io
flp_ret: ; AL = 00 if sucessful
ret ; AL = error code if not
comp_dma: ;Compute 20 bit address from offset, segment
; Entry: AX = segment
; BX = offset
; Exit AX = low 16 bits
; CH = highest 4 bits of address, always less then 16 -
; no megabyte wrap around
;
; The XIOS variables DMA_low16 and DMA_high4 are
; set by this routine. These variables are transferred
; to the floppy disk controller by the routine DMA_SET_UP.
mov cl,4 ! rol ax,cl ;make paragraphs into bytes
mov ch,al ! and al,0f0h ;save high 4 bits, 0 low 4 bits
add ax,bx ;add byte offset
adc ch,0 ! and ch,0fh ;add in the carry, page is less than
mov dma_low16,ax ;16
mov dma_high4,ch
ret
; deblock transfers across 64k boundary by read/write locally
flp_deblock:
mov al,ah ;how many sectors fit in this page ?
xor ah,ah
shr ax,1 ;divided by 512
test ax,ax ;if no sectors, skip to local_rw
jz flp_local_rw
mov num_sec,al ;sectors to read
sub track_mcnt,al ;track_mcnt always > AL
call floppy_io ;read them, dma already computed
jnz flp_deblock_err
xor ax,ax
mov al,num_sec ;compute new DMA offset
add sector,ax ;still on the same track
xchg ah,al ;shl ax,8 (* 256)
shl ah,1 ;* bytes_per_sector (512)
add dma_off,ax ;64K wrap around is legal
flp_local_rw:
cmp fdc_command,fdc_cmnd_write
jnz flp_deblock_op ;skip if not writing
push ds ! push es
mov si,dma_off
mov di,offset local_buffer
push ds ! pop es ;local destination
mov ds,dma_seg
mov cx,bytes_per_sector/2
rep movsw ;move dma to local
pop es ! pop ds
flp_deblock_op:
mov bx,offset local_buffer ;deblock spanning sector
mov ax,ds ;compute 20 bit local DMA addr
call comp_dma
mov num_sec,1 ;read one sector
call floppy_io ;XIOS data cannot span 64K page
jnz flp_deblock_err ;return error
inc sector ! dec track_mcnt
cmp fdc_command,fdc_cmnd_read
jnz flp_deblock_done ;skip if not reading
push es
mov di,dma_off ;move the sector to user's area
mov si,offset local_buffer
mov es,dma_seg
mov cx,bytes_per_sector/2
rep movsw
pop es
flp_deblock_done:
add dma_off,bytes_per_sector
xor al,al ;set zero flag for success
ret
flp_deblock_err:
or al,al ;set not zero for error
ret
; FLOPPY_IO performs the physical read and write
; to the physical disk.
floppy_io:
mov ax,track
mov cur_trk,ax ; set track
mov ax,sector
inc ax ; disk sectors start at 1
mov cur_sec,ax ; set sector
mov d_a_number,r_bytes
mov d_a_eot,r_sectors
mov d_a_gpl,r_gap
mov d_a_dtl,r_dtl
call disk_init
call check_disk_op ;see if it was ok
cmp al,'R' ;if retry requested
jz floppy_io ; then go again
test al,al ;set zf if no error
ret ;and return with al
; The following routine does the read or write operation
; as selected by the global variables.
disk_init:
mov disk_error,0 ;clear the global error flag
mov disk_on_going,0FFh ;flag the motor off counter
mov cl,cur_disk
mov al,01h ; lsb only
shl al,cl ; move bit to disk number
test recal_byte,al ; if disk has been recal'd
jnz disk_routine ; then skip to operation
or recal_byte,al ; flag for next time
; First time through, or after controller reset, recal the drive
disk_recal:
call motor_on
call recal ;back to track zero
call wait_sense_get ;sense interrupt cycle
; Drive has been recal'd, continue with operation
disk_routine:
mov retry_counter,max_retry
disk_routine_1:
call motor_on ;make sure the drive is spun up
call seek ;and were on the right track
call wait_sense_get ;sense interrupt cycle
call dma_setup
call disk_operation
mov disk_time_out,60 ;now, watch for too much time
mov dx,fdc_flag ;if more than a second
call flagwait ; then we have a time out error
mov disk_time_out,0 ;shut off the counter
cmp disk_error,80h ;if it's a timeout error
jz disk_ctrl_reset ; then reset the controller
disk_routine_2:
call fdc_status_get
mov al,d_r_st0
and al,0c0h ;mask out for termination bits
jz disk_routine_ok ;if no errors then leap
dec retry_counter ;else see if more retries are allowed
jnz disk_routine_1 ;if so then try whole operation again
disk_routine_ok:
mov disk_on_going,0 ;allow the motor to shut off
ret
; Reset the disk controller following a time out error
disk_ctrl_reset:
cli
mov al,motor_flags ; get motor bit
and al,not fdc_reset_bit ; reset bit low
mov dx,fdc_port
out dx,al ; reset that hummer
mov recal_byte,0 ; recal all drives
mov disk_on_going,0 ; allow motors off
or al,fdc_reset_bit
out dx,al ; unreset it too
sti
call wait_sense_get ; sense interrupt cycle
mov al,d_r_st0 ; get status byte
cmp al,0C0h ; if perfect
jz d_c_respecify ; then redo the specify
mov disk_error,20h ; bad NEC error
ret
d_c_respecify:
jmp flop_specify ; respecify head step
; The following routine reads/writes as directed from the disk.
disk_operation:
mov disk_results,7 ;7 byte result transfer
mov al,fdc_command ;get the requested command
mov d_a_command,al ;drop it in to the command block
cmp al,fdc_cmnd_format ;if formating
jz disk_op_format ; then skip
mov disk_arguments,9 ;9 byte command string
jmp fdc_command_put ;fire off the disk controller
disk_op_format:
push es ;first set up the format block
push ds ! pop es ; for the current cylinder/head.
mov di,offset format_block ;this is done most easily
mov cx,sectors_per_track ; after "seek" sets cyl/head.
mov ax,word ptr d_a_cylinder ;al=cyl, ah=head
disk_op_format_loop:
stosw ;store cylinder/head
inc di ! inc di ;past sector/size
loop disk_op_format_loop ;do for each sector
pop es
mov d_a_cylinder,f_bytes ;now use the usual r/w command
mov d_a_head,f_sectors ; string for the format command.
mov d_a_record,f_gap ;the names don't match the
mov d_a_number,f_filler ; but we promise not to tell.
mov disk_arguments,6 ;format command is shorter
jmp fdc_command_put ;fire off the disk controller
; The following routine homes the head on the selected disk drive.
recal:
mov disk_arguments,2 ;specify number of arguments
mov d_a_command,fdc_cmnd_recal
mov disk_results,1 ;request 1 result read
mov al,cur_disk ;get current disk
mov d_a_drive,al ;set up the command block
call fdc_command_put ;go send the command block
ret
; The following routine seeks to the selected track on the
; selected drive
seek:
mov disk_results,1 ;only one status byte returned
mov disk_arguments,3 ;request 3 byte command transfer
mov d_a_command,fdc_cmnd_seek
mov bl,0 ;get a head 0
mov ax,cur_trk
cmp al,40 ;test for off side 1
jb side_ok ;if single sided then leap
mov bl,1 ;else get a head 1
neg al ;and wrap around the edge
add al,79 ;cyl = 79 - track
side_ok:
mov d_a_head,bl ;set up the head
add bl,bl ;multiply by 2
add bl,bl ;multiply by 4
mov d_a_cylinder,al ;set up the track number
or bl,cur_disk ;mash disk into head
mov d_a_drive,bl ;set up disk number
mov ax,cur_sec ;get starting sector
mov d_a_record,al ;and set it up
add al,num_sec ;compute new end of track ????
dec al
mov d_a_eot,al ;save it
call fdc_command_put ;send the command block
ret
; do a flag wait, sense interrupt and get fdc status
; used by recal, seek, and reset operations
wait_sense_get:
mov dx,fdc_flag
call flagwait
call sense_interrupt ;jolt the less than wonderful 8272
jmp fdc_status_get ;read the status
; The following routine does the sense interrupt command on
; the FDC. It is called after a recal or a seek to test for
; seek complete.
sense_interrupt:
mov disk_results,2 ;2 bytes are returned
mov disk_arguments,1 ;only one byte of command
mov d_a_command,fdc_cmnd_si ;drop in the sense interrupt commmand
call fdc_command_put ;send the command
ret
; floppy disk controller specify command sets head step speed
flop_specify:
mov disk_arguments,3 ; for a specify command
mov d_a_command,fdc_cmnd_spec
mov al,fdc_spec1_var ; pick up step speed
mov d_a_drive,al ; and store it
mov d_a_cylinder,fdc_spec_2 ; just the usual here
jmp fdc_command_put ; set the head step speed
; The following routine sends the command block in the
; DISK_ARGUMENTS table to the 8272 FDC.
; The number of commands to write to the FDC is the
; first item in the table.
fdc_command_put:
mov dx,fdc_stat ;point to the i/o port
mov si,offset disk_arguments ;point to the table of arguments
cld ;make sure we go forward
lodsb ;get the length of the arguments table
mov cl,al ;get it into the count register
sub ch,ch ;zero the high byte
fdc_command_loop:
in al,dx ;get the current control byte
test al,fdc_ready_write ;if not ok to send next byte
jz fdc_command_loop ;then loop waiting
inc dx ;point at the data port
lodsb ;else get the byte to send
out dx,al ;send it
dec dx ;point back at the status port
loop fdc_command_loop ;if not last byte then loop
ret ;else were all done
; The following routine gets the status information from the 8272
; FDC and places them in the table at DISK_RESULTS.
; The first byte in the table is the number of results
; to read from the FDC
fdc_status_get:
push es ;save UDA
mov dx,fdc_stat ;point at the status port
mov ax,ds ;get our data segment
mov es,ax ;into the extra segment
mov di,offset disk_results + 1 ;point to where to put the data
cld ;make sure we go forward
mov cl,disk_results ;fetch the number of expected results
sub ch,ch ;zero the high byte
fdc_status_loop:
in al,dx ;get the current control byte
test al,fdc_ready_read ;if not ok to read next byte
jz fdc_status_loop ;then loop waiting
inc dx ;point at the data port
in al,dx ;get the byte
stosb ;put it in the structure
dec dx ;point back at the status port
loop fdc_status_loop ;if not last then loop
pop es ;restore UDA
ret ;else return
; The following routine sets the DMA device up for a
; read/write operation. The current DMA command word must be
; at DMA_MODE_STORAGE. The read/write operation cannot cross
; a physical 64K boundary.
dma_setup:
out dma_cbpf,al ;reset the byte pointer
mov al,dma_mode_storage ;get the mode byte
out dma_mode_reg,al ;set the mode
mov ax,dma_low16 ;low 16 bits of 20 bit DMA address
out dma_c2_address,al ;send low 8 bits
mov al,ah
out dma_c2_address,al ;send next 8 bits
mov al,dma_high4 ;high 4 bits of 20 bit DMA address
out dma_page_fdc,al
xor ax,ax
mov ah,num_sec ;shl num_sec,8 (* 256)
shl ah,1 ;*512
dec ax ;0 relative
out dma_c2_count,al ;set up the low byte
mov al,ah ;get the low byte
out dma_c2_count,al ;and the high byte
mov al,dma_bmsk_fdc ;get the binary channel mask
out dma_bmsk_reg,al ;enable the disk channel
ret
; The following routine resets the motor_off_counter and tests
; the current motor_flags against the selected drive.
motor_on:
mov motor_off_counter,40h ;extend the motor off counter
mov al,010h ;pick up a bit for motor a
mov cl,cur_disk ;fetch the binary drive code
shl al,cl ;make it a bit for motor x
mov ah,motor_flags ;fetch the motor bits
test ah,al ;check to see if its on
jnz motor_on_done ;yes then leap
or al,fdc_on ;mask in the no reset,enable interupt
or al,cur_disk ;mask in the drive
mov motor_flags,al ;save for later
mov dx,fdc_port ;point to the port number
out dx,al ;select & motor on
mov dx,ticks_per_second/8 ;wait 1/8 of second for the
mov cl,p_delay ;motor to spin up on writes
call supif
motor_on_done:
ret
; The following routine checks to see if the last
; disk operation was OK. It returns with the zero flag
; set if it was OK or if the error is to be ignored.
; exit: al = FFh for accept error
; 00h for no error or ignore error
; 'R' for retry operation
check_disk_op:
mov al,d_r_st0 ; get the first result byte
and al,0C0h ; see if ok
jnz flop_error ; no then leap
ret ; al = 0 for no error
flop_error:
mov cl,cur_disk ; force a recal on next op
mov al,0FEh ; lsb off
shl al,cl ; move off bit to disk number
and recal_byte,al ; this drive not recal'd
cmp disk_error,0 ; if error code is there
jnz flop_error_go ; then skip the lookup
mov si,offset flop_er_tbl ; stat bits / error codes
mov cx,flop_er_size ; table length
flop_error_loop:
lodsw ; get stat bits
test d_r_st12,ax ; test received status
jnz flop_error_found ; if this is the one
inc si ; past error code
loop flop_error_loop
flop_error_found:
lodsb ; fetch the error code
mov disk_error,al ; and store for message
flop_error_go:
jmp do_disk_error ; return A=FFh, I=00h, R='R'
; *** Memory Disk Routines ***
; Select Memory Disk
select_mdisk:
mov ax,dph_tbl[si] ; fetch dph pointer
ret
; Memory Disk read
read_mdisk:
push ds ! push es
call mdisk_calc ;calculate byte address
les di,dword ptr dmaoff ;load destination DMA address
sub si,si ;setup source DMA address
mov ds,bx ;load pointer to sector in memory
jmps mdisk_common ;jump to shared code
; Memory Disk write
write_mdisk:
push ds ! push es
call mdisk_calc ;calculate byte address
mov es,bx ;setup destination DMA address
sub di,di
lds si,dword ptr dmaoff ;load source DMA address
mdisk_common:
rep movsw ;move between user and memory
pop es ! pop ds
xor ax,ax ;return no error
ret
; Calculate mdisk offset into memory
; output: BX = sector paragraph address
; CX = length in words to transfer
mdisk_calc:
mov bx,track ;pickup track number
mov cl,3 ;8 sectors per track
shl bx,cl
add bx,sector ;gives absolute sector number
mov cl,5 ;times 32 for paragraph of sector start
shl bx,cl
add bx,mdisk_start ;plus base address of disk in memory
mov ch,mcnt
mov cl,0 ;cx = 256 * mcnt = words to move
ret
; *** Disk Error Handling Routine ***
; This is called on any disk error from either
; the floppy or hard disk drivers.
; entry: disk_error = ROS error code
; exit: al = 00h for ignore error (treat op as sucessful)
; 01h for accept error
; 02h for accept write protect error
; 'R' for retry operation
uda_err_mode equ byte ptr .10h ; error mode byte in uda
err_mode_code equ 0FEh ; or 0FFh for quick return
wp_code equ 03h ; ROS definition
do_disk_error:
cmp es:uda_err_mode,err_mode_code
jae disk_error_accept ; skip if quick return
mov al,drive
add al,'A'
mov disk_er_drive,al ; save drive code
; save track number
push es
push ds ! pop es
mov di,offset disk_er_track
mov ax,track
call store_track ; into the error message
mov di,offset disk_er_codes
mov cx,disk_er_size
mov al,disk_error
repnz scasb ; look for our code
mov ax,di
sub ax,offset disk_er_codes + 1
mov cx,sub_msg_size
mul cl ; ax = sub message index
mov si,ax
add si,offset sub_msg_tbl
mov di,offset disk_er_sub
rep movsb ; store the sub message
pop es
mov si,offset disk_er_msg ; finished message
mov di,offset disk_er_resp ; allowable responses
call sl_error_out ; error message to stat line
cmp al,'R' ; if retry,
jz disk_error_done ; then return 'R'
cmp al,'I' ; if ignore
mov al,0 ; then return 00h
jz disk_error_done ; if accept
disk_error_accept:
mov al,1 ; then assume physical
cmp disk_error,wp_code ; but if write protect
jnz disk_error_done ; then return a 2
mov al,2
disk_error_done:
ret
; store the track number
; entry: ax = track number
; di -> track num destination
; es = ds
store_track:
mov word ptr .1[di],' '
mov dh,0 ; for lzb test
div er_hundred ; al = hund's, ah = rem
call store_digit ; print hundred's place
mov al,ah
cbw ; ready for divide
div er_ten
call store_digit ; print ten's place
mov al,ah
mov dh,0FFh ; no lzb on last digit
; jmps store_digit ; print one's place
store_digit:
push ax ; save the number
or dh,al ; if zero, then lead blank
jz store_lzb
or al,'0' ; convert to ascii
stosb ; and store to message
store_lzb:
pop ax ; restore number
ret
eject
;****************************************************************
;* *
;* FLOPPY DISK DRIVER DATA *
;* *
;****************************************************************
reorg13 equ (offset $ + 1) and -2
dseg
org reorg13
max_retry equ 4
; The following tables are used to issue commands to,
; and read results from the 8272 FDC. The first entry
; in each table is the number of bytes to send or receive
; from the device
disk_arguments db 0 ;number of arguments to send
d_a_command db 0 ;command read/write
d_a_drive db 0 ;drive select & head select
d_a_cylinder db 0 ;cylinder to read/write
d_a_head db 0 ;head
d_a_record db 0 ;sector
d_a_number db 2 ;magic number for 512 bytes/sector
d_a_eot db sectors_per_track ;end of track sector number
d_a_gpl db 02ah ;inter sector gap length
d_a_dtl db 0ffh ;data length
disk_results db 0 ;number of bytes to read
d_r_st0 db 0 ;status byte 0
d_r_st1 db 0 ;status byte 1
d_r_st2 db 0 ;status byte 2
d_r_st12 equ word ptr d_r_st1
d_r_cylinder db 0 ;cylinder we are on now
d_r_head db 0
d_r_record db 0
d_r_number db 0 ;number of sectors read
f_a_bytes db 0
f_a_sectors db 0
f_a_gap db 0
f_a_filler db 0
dma_mode_storage db dma_mode_read_fdc ;current dma mode
fdc_command db fdc_cmnd_read ;current fdc mode
cur_disk db 0ffh
cur_trk dw 0
cur_sec dw 0
num_sec db 1 ;num sectors to read/write
;in one call to controller
track_mcnt rb 1 ;multi sector count on
;current track
dma_low16 rw 1 ;20 bit address storage
dma_high4 rb 1
disk_on_going db 0 ;0FFh if disk op happening
retry_counter db 0 ;0 no more retrys left
motor_flags db 0 ;last state of the motor bits
motor_off_counter db 0
fdc_spec1_var db fdc_spec_1 ;head step default
recal_byte db 0 ;which disks have been recal'd
verify_flag db 0 ;verify after disk write?
disk_time_out db 0 ;count down for tick routine
; Format Block consists of eight copies of c,h,r,n data
; which the Floppy Disk Controller uses for formating.
format_block db 0,0,1,f_bytes
db 0,0,2,f_bytes
db 0,0,3,f_bytes
db 0,0,4,f_bytes
db 0,0,5,f_bytes
db 0,0,6,f_bytes
db 0,0,7,f_bytes
db 0,0,8,f_bytes
; Floppy now shares its local buffer with hard disk
; Stack switch area for disk interrupt
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
dw 0cccch,0cccch,0cccch,0cccch
user_save_area rs 0
user_ss dw 0
user_sp dw 0
user_ax dw 0
mdisk_start dw 0D000h ;may be changed in init
; Floppy disk parameter headers
dph0 dw 0000h,0000h ;translate table
dw 0000h,0000h ;scratch area
dw dpbs ;dsk parm block
dw 0ffffh ;check
dw 0ffffh ;alloc vectors
dw 0ffffh ;dir buff cntrl blk
dw 0ffffh ;data buff cntrl blk
dw 0ffffh ;hash table segment
dph1 dw 0000h,0000h ;translate table
dw 0000h,0000h ;scratch area
dw dpbs ;dsk parm block
dw 0ffffh ;check
dw 0ffffh ;alloc vectors
dw 0ffffh ;dir buff cntrl blk
dw 0ffffh ;data buff cntrl blk
dw 0ffffh ;hash table segment
dph2 dw 0000h,0000h ;translate table
dw 0000h,0000h ;scratch area
dw dpbs ;dsk parm block
dw 0ffffh ;check
dw 0ffffh ;alloc vectors
dw 0ffffh ;dir buff cntrl blk
dw 0ffffh ;data buff cntrl blk
dw 0ffffh ;hash table segment
dph3 dw 0000h,0000h ;translate table
dw 0000h,0000h ;scratch area
dw dpbs ;dsk parm block
dw 0ffffh ;check
dw 0ffffh ;alloc vectors
dw 0ffffh ;dir buff cntrl blk
dw 0ffffh ;data buff cntrl blk
dw 0ffffh ;hash table segment
dph_md dw 0000h,0000h ;translate table
dw 0000h,0000h ;scratch area
dw dpb_md ;dsk parm block
dw 0000h ;no check
dw 0ffffh ;alloc vectors
dw 0ffffh ;dir buff cntrl blk
dw 0ffffh ;data buff cntrl blk
dw 0ffffh ;hash table segment
; single sided floppy parameter block
dpbs dw 8 ;sectors per track
db 3 ;block shift
db 7 ;block mask
db 0 ;extnt mask
dw 155 ;disk size in 1k blocks
;less offset track(s)
dw 63 ;directory max
db 11000000b ;alloc0
db 0 ;alloc1
dw 16 ;check size
dw 1 ;offset
db 2 ;phys sec shift
db 3 ;phys sec mask
; double sided floppy parameter block
dpbd dw 8 ;sectors per track
db 4 ;block shift
db 15 ;block mask
db 1 ;extnt mask
dw 157 ;disk size in 2k blocks
;less offset track(s)
dw 63 ;directory max
db 10000000b ;alloc0
db 0 ;alloc1
dw 16 ;check size
dw 1 ;offset
db 2 ;phys sec shift
db 3 ;phys sec mask
; memory disk parameter block
dpb_md dw 8 ;sectors per track
db 4 ;block shift
db 15 ;block mask
db 1 ;extnt mask
dsm_md dw 191 ;max disk size in 2k blocks
;recalculated in init
dw 63 ;directory max
db 10000000b ;alloc0
db 0 ;alloc1
dw 8000h ;;check size, changed to show permanent media
dw 0 ;offset
db 2 ;phys sec shift
db 3 ;phys sec mask
;************************************************
;* *
;* DISK ERROR MESSAGE DATA AREA *
;* *
;************************************************
disk_error rb 1 ; ROS error code store
; Table of floppy status bits versus ROS error codes
flop_er_tbl db 10h,01h,40h ; bad seek
db 20h,20h,10h ; bad crc
db 04h,00h,04h ; sector not found
db 02h,00h,03h ; write protect
db 01h,01h,02h ; bad addr mark
flop_er_size equ (offset $ - offset flop_er_tbl)/3
db 0BBh ; unknown error
disk_er_codes db 01h,02h,03h,04h,05h,07h
db 08h,09h,0Bh,10h,11h,20h
db 40h,80h,0AAh,0FFh,0BBh
disk_er_size equ offset $ - offset disk_er_codes
sub_msg_size equ 19
sub_msg_tbl db ' ROS Command Error ' ; 01h
db ' Bad Address Mark ' ; 02h
db ' Write-Protected ' ; 03h
db ' Record Not Found ' ; 04h
db ' Can''t Reset Disk ' ; 05h
db ' Drive Setup Error ' ; 07h
db ' DMA Chip Failure ' ; 08h
db ' DMA Address Error ' ; 09h
db 'Bad Track Flag Set ' ; 0Bh
db 'Uncorrectable Data ' ; 10h
db 'Data Was Corrected ' ; 11h
db 'Bad Disk Controller' ; 20h
db 'Head Position Error' ; 40h
db ' No Response ' ; 80h
db 'Read Doesn''t Match ' ; AAh
db 'Can''t Sense Status ' ; FFh
db ' Error Not Defined ' ; BBh and default
disk_er_msg db 'Disk Error Drive '
disk_er_drive db 'X: Track '
disk_er_track db 'XXX '
disk_er_sub db 'Some sort of detail '
db ' Retry, Ignore, Accept? '
disk_er_resp db 3,'RIA'
er_hundred db 100 ; for track divide
er_ten db 10

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