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Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 86/CPM 86 1.1 SOURCE/BIOS.A86
Sepp J Morris 31738079c4 Upload 
Digital Research
2020-11-06 18:50:37 +01:00

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title '8086 Disk I/O Drivers'
;*********************************************
;* *
;* Basic Input/Output System (BIOS) for *
;* CP/M-86 Configured for iSBC 86/12 with *
;* the iSBC 204 Floppy Disk Controller *
;* *
;* (Note: this file contains both embedded *
;* tabs and blanks to minimize the list file *
;* width for printing purposes. You may wish*
;* to expand the blanks before performing *
;* major editing.) *
;*********************************************
; Copyright (C) 1980,1981
; Digital Research, Inc.
; Box 579, Pacific Grove
; California, 93950
;
; (Permission is hereby granted to use
; or abstract the following program in
; the implementation of CP/M, MP/M or
; CP/NET for the 8086 or 8088 Micro-
; processor)
true equ -1
false equ not true
;*********************************************
;* *
;* Loader_bios is true if assembling the *
;* LOADER BIOS, otherwise BIOS is for the *
;* CPM.SYS file. Blc_list is true if we *
;* have a serial printer attached to BLC8538 *
;* Bdos_int is interrupt used for earlier *
;* versions. *
;* *
;*********************************************
loader_bios equ false
blc_list equ true
bdos_int equ 224 ;reserved BDOS Interrupt
IF not loader_bios
;---------------------------------------------
;| |
bios_code equ 2500h
ccp_offset equ 0000h
bdos_ofst equ 0B06h ;BDOS entry point
;| |
;---------------------------------------------
ENDIF ;not loader_bios
IF loader_bios
;---------------------------------------------
;| |
bios_code equ 1200h ;start of LDBIOS
ccp_offset equ 0003h ;base of CPMLOADER
bdos_ofst equ 0406h ;stripped BDOS entry
;| |
;---------------------------------------------
ENDIF ;loader_bios
csts equ 0DAh ;i8251 status port
cdata equ 0D8h ; " data port
IF blc_list
;---------------------------------------------
;| |
lsts equ 41h ;2651 No. 0 on BLC8538 status port
ldata equ 40h ; " " " " " data port
blc_reset equ 60h ;reset selected USARTS on BLC8538
;| |
;---------------------------------------------
ENDIF ;blc_list
;*********************************************
;* *
;* Intel iSBC 204 Disk Controller Ports *
;* *
;*********************************************
base204 equ 0a0h ;SBC204 assigned address
fdc_com equ base204+0 ;8271 FDC out command
fdc_stat equ base204+0 ;8271 in status
fdc_parm equ base204+1 ;8271 out parameter
fdc_rslt equ base204+1 ;8271 in result
fdc_rst equ base204+2 ;8271 out reset
dmac_adr equ base204+4 ;8257 DMA base address out
dmac_cont equ base204+5 ;8257 out control
dmac_scan equ base204+6 ;8257 out scan control
dmac_sadr equ base204+7 ;8257 out scan address
dmac_mode equ base204+8 ;8257 out mode
dmac_stat equ base204+8 ;8257 in status
fdc_sel equ base204+9 ;FDC select port (not used)
fdc_segment equ base204+10 ;segment address register
reset_204 equ base204+15 ;reset entire interface
max_retries equ 10 ;max retries on disk i/o
;before perm error
cr equ 0dh ;carriage return
lf equ 0ah ;line feed
cseg
org ccpoffset
ccp:
org bios_code
;*********************************************
;* *
;* BIOS Jump Vector for Individual Routines *
;* *
;*********************************************
jmp INIT ;Enter from BOOT ROM or LOADER
jmp WBOOT ;Arrive here from BDOS call 0
jmp CONST ;return console keyboard status
jmp CONIN ;return console keyboard char
jmp CONOUT ;write char to console device
jmp LISTOUT ;write character to list device
jmp PUNCH ;write character to punch device
jmp READER ;return char from reader device
jmp HOME ;move to trk 00 on cur sel drive
jmp SELDSK ;select disk for next rd/write
jmp SETTRK ;set track for next rd/write
jmp SETSEC ;set sector for next rd/write
jmp SETDMA ;set offset for user buff (DMA)
jmp READ ;read a 128 byte sector
jmp WRITE ;write a 128 byte sector
jmp LISTST ;return list status
jmp SECTRAN ;xlate logical->physical sector
jmp SETDMAB ;set seg base for buff (DMA)
jmp GETSEGT ;return offset of Mem Desc Table
jmp GETIOBF ;return I/O map byte (IOBYTE)
jmp SETIOBF ;set I/O map byte (IOBYTE)
;*********************************************
;* *
;* INIT Entry Point, Differs for LDBIOS and *
;* BIOS, according to "Loader_Bios" value *
;* *
;*********************************************
INIT: ;print signon message and initialize hardware
mov ax,cs ;we entered with a JMPF so use
mov ss,ax ; CS: as the initial value of SS:,
mov ds,ax ; DS:,
mov es,ax ; and ES:
;use local stack during initialization
mov sp,offset stkbase
cld ;set forward direction
IF not loader_bios
;---------------------------------------------
;| |
; This is a BIOS for the CPM.SYS file.
; Setup all interrupt vectors in low
; memory to address trap
push ds ;save the DS register
mov ax,0
mov ds,ax
mov es,ax ;set ES and DS to zero
;setup interrupt 0 to address trap routine
mov int0_offset,offset int_trap
mov int0_segment,CS
mov di,4
mov si,0 ;then propagate
mov cx,510 ;trap vector to
rep movs ax,ax ;all 256 interrupts
;BDOS offset to proper interrupt
mov bdos_offset,bdos_ofst
pop ds ;restore the DS register
;*********************************************
;* *
;* National "BLC 8538" Channel 0 for a serial*
;* 9600 baud printer - this board uses 8 Sig-*
;* netics 2651 Usarts which have on-chip baud*
;* rate generators. *
;* *
;*********************************************
mov al,0FFh
out blc_reset,al ;reset all usarts on 8538
mov al,4Eh
out ldata+2,al ;set usart 0 in async 8 bit mode
mov al,3Eh
out ldata+2,al ;set usart 0 to 9600 baud
mov al,37h
out ldata+3,al ;enable Tx/Rx, and set up RTS,DTR
;| |
;---------------------------------------------
ENDIF ;not loader_bios
IF loader_bios
;---------------------------------------------
;| |
;This is a BIOS for the LOADER
push ds ;save data segment
mov ax,0
mov ds,ax ;point to segment zero
;BDOS interrupt offset
mov bdos_offset,bdos_ofst
mov bdos_segment,CS ;bdos interrupt segment
pop ds ;restore data segment
;| |
;---------------------------------------------
ENDIF ;loader_bios
mov bx,offset signon
call pmsg ;print signon message
mov cl,0 ;default to dr A: on coldstart
jmp ccp ;jump to cold start entry of CCP
WBOOT: jmp ccp+6 ;direct entry to CCP at command level
IF not loader_bios
;---------------------------------------------
;| |
int_trap:
cli ;block interrupts
mov ax,cs
mov ds,ax ;get our data segment
mov bx,offset int_trp
call pmsg
hlt ;hardstop
;| |
;---------------------------------------------
ENDIF ;not loader_bios
;*********************************************
;* *
;* CP/M Character I/O Interface Routines *
;* Console is Usart (i8251a) on iSBC 86/12 *
;* at ports D8/DA *
;* *
;*********************************************
CONST: ;console status
in al,csts
and al,2
jz const_ret
or al,255 ;return non-zero if RDA
const_ret:
ret ;Receiver Data Available
CONIN: ;console input
call const
jz CONIN ;wait for RDA
in al,cdata
and al,7fh ;read data and remove parity bit
ret
CONOUT: ;console output
in al,csts
and al,1 ;get console status
jz CONOUT ;wait for TBE
mov al,cl
out cdata,al ;Transmitter Buffer Empty
ret ;then return data
LISTOUT: ;list device output
IF blc_list
;---------------------------------------------
;| |
call LISTST
jz LISTOUT ;wait for printer not busy
mov al,cl
out ldata,al ;send char to TI 810
;| |
;---------------------------------------------
ENDIF ;blc_list
ret
LISTST: ;poll list status
IF blc_list
;---------------------------------------------
;| |
in al,lsts
and al,81h ;look at both TxRDY and DTR
cmp al,81h
jnz zero_ret ;either false, printer is busy
or al,255 ;both true, LPT is ready
;| |
;---------------------------------------------
ENDIF ;blc_list
ret
PUNCH: ;not implemented in this configuration
READER:
mov al,1ah
ret ;return EOF for now
GETIOBF:
mov al,0 ;TTY: for consistency
ret ;IOBYTE not implemented
SETIOBF:
ret ;iobyte not implemented
zero_ret:
and al,0
ret ;return zero in AL and flags
; Routine to get and echo a console character
; and shift it to upper case
uconecho:
call CONIN ;get a console character
push ax
mov cl,al ;save and
call CONOUT
pop ax ;echo to console
cmp al,'a'
jb uret ;less than 'a' is ok
cmp al,'z'
ja uret ;greater than 'z' is ok
sub al,'a'-'A' ;else shift to caps
uret:
ret
; utility subroutine to print messages
pmsg:
mov al,[BX] ;get next char from message
test al,al
jz return ;if zero return
mov CL,AL
call CONOUT ;print it
inc BX
jmps pmsg ;next character and loop
;*********************************************
;* *
;* Disk Input/Output Routines *
;* *
;*********************************************
SELDSK: ;select disk given by register CL
mov bx,0000h
cmp cl,2 ;this BIOS only supports 2 disks
jnb return ;return w/ 0000 in BX if bad drive
mov al, 80h
cmp cl,0
jne sel1 ;drive 1 if not zero
mov al, 40h ;else drive is 0
sel1: mov sel_mask,al ;save drive select mask
;now, we need disk parameter address
mov ch,0
mov bx,cx ;BX = word(CL)
mov cl,4
shl bx,cl ;multiply drive code * 16
;create offset from Disk Parameter Base
add bx,offset dp_base
return:
ret
HOME: ;move selected disk to home position (Track 0)
mov trk,0 ;set disk i/o to track zero
mov bx,offset hom_com
call execute
jz return ;home drive and return if OK
mov bx,offset bad_hom ;else print
call pmsg ;"Home Error"
jmps home ;and retry
SETTRK: ;set track address given by CX
mov trk,cl ;we only use 8 bits of track address
ret
SETSEC: ;set sector number given by cx
mov sect,cl ;we only use 8 bits of sector address
ret
SECTRAN: ;translate sector CX using table at [DX]
mov bx,cx
add bx,dx ;add sector to tran table address
mov bl,[bx] ;get logical sector
ret
SETDMA: ;set DMA offset given by CX
mov dma_adr,CX
ret
SETDMAB: ;set DMA segment given by CX
mov dma_seg,CX
ret
;
GETSEGT: ;return address of physical memory table
mov bx,offset seg_table
ret
;*********************************************
;* *
;* All disk I/O parameters are setup: the *
;* Read and Write entry points transfer one *
;* sector of 128 bytes to/from the current *
;* DMA address using the current disk drive *
;* *
;*********************************************
READ:
mov al,12h ;basic read sector command
jmps r_w_common
WRITE:
mov al,0ah ;basic write sector command
r_w_common:
mov bx,offset io_com ;point to command string
mov byte ptr 1[BX],al ;put command into string
; fall into execute and return
execute: ;execute command string.
;[BX] points to length,
; followed by Command byte,
; followed by length-1 parameter bytes
mov last_com,BX ;save command address for retries
outer_retry:
;allow some retrying
mov rtry_cnt,max_retries
retry:
mov BX,last_com
call send_com ;transmit command to i8271
; check status poll
mov BX,last_com
mov al,1[bx] ;get command op code
mov cx,0800h ;mask if it will be "int req"
cmp al,2ch
jb exec_poll ;ok if it is an interrupt type
mov cx,8080h ;else we use "not command busy"
and al,0fh
cmp al,0ch ;unless there isn't
mov al,0
ja exec_exit ; any result
;poll for bits in CH,
exec_poll: ; toggled with bits in CL
in al,fdc_stat ;read status
and al,ch
xor al,cl ; isolate what we want to poll
jz exec_poll ;and loop until it is done
;Operation complete,
in al,fdc_rslt ; see if result code indicates error
and al,1eh
jz exec_exit ;no error, then exit
;some type of error occurred . . .
cmp al,10h
je dr_nrdy ;was it a not ready drive ?
;no,
dr_rdy: ; then we just retry read or write
dec rtry_cnt
jnz retry ; up to 10 times
; retries do not recover from the
; hard error
mov ah,0
mov bx,ax ;make error code 16 bits
mov bx,errtbl[BX]
call pmsg ;print appropriate message
in al,cdata ;flush usart receiver buffer
call uconecho ;read upper case console character
cmp al,'C'
je wboot_l ;cancel
cmp al,'R'
je outer_retry ;retry 10 more times
cmp al,'I'
je z_ret ;ignore error
or al,255 ;set code for permanent error
exec_exit:
ret
dr_nrdy: ;here to wait for drive ready
call test_ready
jnz retry ;if it's ready now we are done
call test_ready
jnz retry ;if not ready twice in row,
mov bx,offset nrdymsg
call pmsg ;"Drive Not Ready"
nrdy01:
call test_ready
jz nrdy01 ;now loop until drive ready
jmps retry ;then go retry without decrement
zret:
and al,0
ret ;return with no error code
wboot_l: ;can't make it w/ a short leap
jmp WBOOT
;*********************************************
;* *
;* The i8271 requires a read status command *
;* to reset a drive-not-ready after the *
;* drive becomes ready *
;* *
;*********************************************
test_ready:
mov dh, 40h ;proper mask if dr 1
test sel_mask,80h
jnz nrdy2
mov dh, 04h ;mask for dr 0 status bit
nrdy2:
mov bx,offset rds_com
call send_com
dr_poll:
in al,fdc_stat ;get status word
test al,80h
jnz dr_poll ;wait for not command busy
in al,fdc_rslt ;get "special result"
test al,dh ;look at bit for this drive
ret ;return status of ready
;*********************************************
;* *
;* Send_com sends a command and parameters *
;* to the i8271: BX addresses parameters. *
;* The DMA controller is also initialized *
;* if this is a read or write *
;* *
;*********************************************
send_com:
in al,fdc_stat
test al,80h ;insure command not busy
jnz send_com ;loop until ready
;see if we have to initialize for a DMA operation
mov al,1[bx] ;get command byte
cmp al,12h
jne write_maybe ;if not a read it could be write
mov cl,40h
jmps init_dma ;is a read command, go set DMA
write_maybe:
cmp al,0ah
jne dma_exit ;leave DMA alone if not read or write
mov cl,80h ;we have write, not read
init_dma:
;we have a read or write operation, setup DMA controller
; (CL contains proper direction bit)
mov al,04h
out dmac_mode,al ;enable dmac
mov al,00
out dmac_cont,al ;send first byte to control port
mov al,cl
out dmac_cont,al ;load direction register
mov ax,dma_adr
out dmac_adr,al ;send low byte of DMA
mov al,ah
out dmac_adr,al ;send high byte
mov ax,dma_seg
out fdc_segment,al ;send low byte of segment address
mov al,ah
out fdc_segment,al ;then high segment address
dma_exit:
mov cl,[BX] ;get count
inc BX
mov al,[BX] ;get command
or al,sel_mask ;merge command and drive code
out fdc_com,al ;send command byte
parm_loop:
dec cl
jz exec_exit ;no (more) parameters, return
inc BX ;point to (next) parameter
parm_poll:
in al,fdc_stat
test al,20h ;test "parameter register full" bit
jnz parm_poll ;idle until parm reg not full
mov al,[BX]
out fdc_parm,al ;send next parameter
jmps parm_loop ;go see if there are more parameters
;*********************************************
;* *
;* Data Areas *
;* *
;*********************************************
data_offset equ offset $
dseg
org data_offset ;contiguous with code segment
IF loader_bios
;---------------------------------------------
;| |
signon db cr,lf,cr,lf
db 'CP/M-86 Version 2.2',cr,lf,0
;| |
;---------------------------------------------
ENDIF ;loader_bios
IF not loader_bios
;---------------------------------------------
;| |
signon db cr,lf,cr,lf
db ' System Generated - 11 Jan 81',cr,lf,0
;| |
;---------------------------------------------
ENDIF ;not loader_bios
bad_hom db cr,lf,'Home Error',cr,lf,0
int_trp db cr,lf,'Interrupt Trap Halt',cr,lf,0
errtbl dw er0,er1,er2,er3
dw er4,er5,er6,er7
dw er8,er9,erA,erB
dw erC,erD,erE,erF
er0 db cr,lf,'Null Error ??',0
er1 equ er0
er2 equ er0
er3 equ er0
er4 db cr,lf,'Clock Error :',0
er5 db cr,lf,'Late DMA :',0
er6 db cr,lf,'ID CRC Error :',0
er7 db cr,lf,'Data CRC Error :',0
er8 db cr,lf,'Drive Not Ready :',0
er9 db cr,lf,'Write Protect :',0
erA db cr,lf,'Trk 00 Not Found :',0
erB db cr,lf,'Write Fault :',0
erC db cr,lf,'Sector Not Found :',0
erD equ er0
erE equ er0
erF equ er0
nrdymsg equ er8
rtry_cnt db 0 ;disk error retry counter
last_com dw 0 ;address of last command string
dma_adr dw 0 ;dma offset stored here
dma_seg dw 0 ;dma segment stored here
sel_mask db 40h ;select mask, 40h or 80h
; Various command strings for i8271
io_com db 3 ;length
rd_wr db 0 ;read/write function code
trk db 0 ;track #
sect db 0 ;sector #
hom_com db 2,29h,0 ;home drive command
rds_com db 1,2ch ;read status command
; System Memory Segment Table
segtable db 2 ;2 segments
dw tpa_seg ;1st seg starts after BIOS
dw tpa_len ;and extends to 08000
dw 2000h ;second is 20000 -
dw 2000h ;3FFFF (128k)
include singles.lib ;read in disk definitions
loc_stk rw 32 ;local stack for initialization
stkbase equ offset $
lastoff equ offset $
tpa_seg equ (lastoff+0400h+15) / 16
tpa_len equ 0800h - tpa_seg
db 0 ;fill last address for GENCMD
;*********************************************
;* *
;* Dummy Data Section *
;* *
;*********************************************
dseg 0 ;absolute low memory
org 0 ;(interrupt vectors)
int0_offset rw 1
int0_segment rw 1
; pad to system call vector
rw 2*(bdos_int-1)
bdos_offset rw 1
bdos_segment rw 1
END

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