;
; DOS SIMULATOR
;
; MODIFICATIONS TO CP/M TO IMPROVE ITS COMPATIBILITY
; WITH CROMENCO'S DISK OPERATING SYSTEM.
;
; NOTE: CROMENCOS DISK SYSTEM TREATS CP/M
; CALLS AS A SUBSET OF THEIR OWN SYSTEM, IN
; ADDITION, SEVERAL OF THE CP/M CALLS HAVE
; BEEN EMBLISHED.
;
; NOT ALL OF THE SPECIAL CALLS HAVE BEEN COVERED BY
; THESE MODIFICATIONS. ALSO YOU WILL NEED A Z80 PROCESSOR
; TO RUN MOST PROGRAMS WRITEN FOR THE CROMENCO
; DISK SYSTEM.
;
; IMPLEMNTATION NOTES:
;
; (1) CPMB = STARTING ADDRESS OF CP/M BDOS
; (2) THESE INTERNAL LOCATIONS ARE FOR
; CP/M VERSION 1.4. (AND CAN BE EXPECTED TO VARY)
; (A) CPMB+807H, A JUMP IN CP/M WHICH
; IS REPLACED BY A JUMP TO DSIM.
; (B) CPMB+0A07H, A FLAG/CHR BUFFER USED
; BY THE CP/M I/O ROUTINES
; (C) CPMB+869H, 8FAH, AND 9F8H FOR
; THE CONTROL C ADDRESS.
; (3) IN THE GOCPM ROUTINE IN WARM BOOT, ADD:
; LXI H,DSIM
; SHLD CPMB+807H
; THIS PROVIDES THE LINK TO DSIM
; (4) DSIM CAN RESIDE IN THE CBIOS.
; (5) REMEMBER, DON'T LET THE CBIOS GET TO
; LONG, OR THERE WON'T BE SPACE FOR IT
; ON THE DISK.
; (6) DMAADD IS ADDRESS OF LOCATION WHERE CP/M STORES
; THE DMA ADDRESS.
;
; DOS SIMULATOR
;
; FIRST SORT OUT THE CP/M CALLS WE
; NEED TO MODIFY.
;
DSIM: MOV A,C ; GET COMMAND
CPI 0AH ; READ BUFFER?
JZ FLIN ; YES
CPI 0FH ; OPEN FILE?
JZ FHL ; YES
CPI 11H ; SEARCH FOR FILE?
JZ FHL ; YES
CPI 12H ; SEARCH FOR NEXT?
JZ FHL ; YES
ORA A ; RETURN TO DOS?
JZ WBOOT ; YES
JMP CPMB+841H ; IF BIT=7=0 NORMAL CPM
;
; ADDED CALLS
;
ANI 0FH ; INPUT W/OUT ECHO
JZ CONIN1 ; YES
CPI 02H ; CONTROL C?
JZ SCC ; YES
CPI 06H ; SET UP FCB?
JZ SFCB ; YES
CPI 09H ; DO DE=DE*HL?
JZ CMULT ; YES
CPI 0AH ; DO HL=HL/DE?
JZ SDIV ; YES
;
; IF WE GET HERE, CALL IS NOT HANDLED
; THIS JUMP IS TO THE BREAKPOINT ROUTINE
; IN MY PROM MONITOR, AND SHOULD BE REPLACED
; ANYWAY YOU SEE FIT
;
JMP 0C108H
;
; CHANGE CONTROL C ADDRESS
;
SCC: XCHG ; GET ADDRESS
SHLD CPMB+869H
SHLD CPMB+8FAH
SHLD CPMB+9F8H
XRA A
RET
;
; ADD NULL TO INPUT BUFFER
;
FLIN: PUSH D ; SAVE BUFFER ADD
CALL CPMB+841H ; GO GET INPUT
POP H ; GET ADDRESS
MOV A,M ; REQ. NO.
INX H
MOV C,M ; ACTUAL
CMP C
RZ ; BUFFER FULL
INX H ; FIRST CHAR
XRA A
MOV B,A
DAD B ; GET LAST LOC
MOV M,A ; ADD NULL
RET
;
; NON ECHO CONSOLE INPUT
;
CONIN1: LDA CPMB+0A07H ; CPM CHR READY FLAG
ORA A
JNZ CONIN2 ; ONE WAITING
CALL CONIN
CONIN2: PUSH PSW
XRA A ; CLEAR FLAG
STA CPMB+0A07H
POP PSW
RET
;
; SIMPLE DIVIDE
;
SDIV: MOV A,D ; CHECK FOR ZERO
ORA E
JNZ SDIV1
MOV L,A ; ANSWER
MOV H,A
DCR A ; A=FF
RET
SDIV1: LXI B,1
SDIV2: MOV A,L
SUB E
MOV L,A
MOV A,H
SBB D
MOV H,A
JM SDIV3
INX B
JMP SDIV2
;
SDIV3: DAD D
DCX B
XCHG
PUSH B
POP H
XRA A
RET
;
; MULTIPLY
;
CMULT: MVI A,10H
STA SHFT ; TO DO
PUSH H ; SWAP
POP B
LXI H,0 ; ZERO
CMULT1: DAD H ; SHIFT PRODUCT
ORA A ; CLR CARRY
MOV A,E ; 16 BIT SHIFT
RAL
MOV E,A
MOV A,D
RAL
MOV D,A
JNC CMULT2 ; IF NO CY, SKIP
DAD B ; ADD
CMULT2: LDA SHFT ; SEE IF DONE
DCR A
STA SHFT ; JUST IN CASE
JNZ CMULT1 ; MORE
PUSH H
POP D
RET
;
; FIX HL ON SEARCH, OPEN COMMANDS
;
FHL: CALL CPMB+841H
CPI 0FFH ; SKIP?
RZ ; YES
PUSH PSW
RRC
RRC
RRC
ANI 60H
LHLD DMAADD
MVI D,0
MOV E,A
FHL1: DAD D ; BASE ADDRESS
MOV A,M ; EMPTY?
CPI 0E5H
JZ FHLE ; YES, SKIP
PUSH H ; SAVE
LXI D,0FH ; CHECK EXT
DAD D
MOV A,M
CPI 80H ; FULL?
JNZ FHLE1
MVI A,0EFH
CMP L
JZ FHLE1
POP H
LXI D,20H
JMP FHL1
;
FHLE1: POP H
FHLE: POP PSW
RET
; SET UP FILE CONTROL BLOCK
;
; HL=SORCE
; DE=DEST
; FIRST CLEAR FCB
;
SFCB: XCHG
PUSH H ; SAVE FOR EXIT
MVI M,0
INX D ; LOOK FOR COLON
LDAX D ; GET CHAR
DCX D ; IF NOT A COLON
CPI ':'
JNZ SFCB7 ; NOPE
LDAX D ; GET DRIVE
ANI 03H ; STRIP
MOV M,A ; SET FCB
INX D ; AHEAD TO NAME
INX D
SFCB7: INX H
PUSH H ; FOR FILENAME
MVI A,11
SFCB1: MVI M,20H ; SPACE
INX H
DCR A
JNZ SFCB1
MVI A,21 ; CLEAR
SFCB2: MVI M,0
INX H
DCR A
JNZ SFCB2
POP H
PUSH H
;
; HL=FCB+1
; DE=SCORCE
; STACK=FCB+1,FCB
;
MVI C,8+1
SFCB3: LDAX D
CPI '.'
JZ SFCB4
CPI '/'
JM SEXIT
DCR C
JZ SFCB5
MOV M,A
INX H
INX D
JMP SFCB3
;
SFCB4: INX D
SFCB5: POP H
PUSH H ; FOR EXIT
LXI B,8
DAD B
MVI C,3+1
SFCB6: LDAX D
CPI '/'
JM SEXIT
DCR C
JZ SEXIT
MOV M,A
INX H
INX D
JMP SFCB6
;
SEXIT: XCHG
POP D
POP D
RET
;
SHFT: DB 0 ; RAM FOR MULT
;
