IBM PC CONVERTIBLE

Diskette Resyoc (DSKT_RESYNC)
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MODULE-NAME : DSKLRESYNC
DESCRIPTIVE-NAME : DISKETTE RESYNC ROUTINES
COPYRIGHT: 7396-917 (C) COPYRIGHT IBM CORP. 1985
REFER TO COPYRIGHT INSTRUCTIONS FORM NUMBER G120-2083
CHANGE LEVEL: 0.0
FUNCTION : TO POWER ON ANO RE-SYNCHRONIZE THE STATE OF THE DISKETTE
CONTROLLER WITH THE CURRENT STATE OF THE DISKETTE DRIVES
MODULE SIZE: 660 BYTES
ENTRY CONDITIONS:
PURPOSE OF ENTRY: TO POWER UP THE FDC WHEN THE FDC IS POWERED OFF
INPUT CONDITIONS: DS POINTING TO ROM DATA AREA, BP POINTING
TO STACK
RESTRICTIONS: NONE
THIS ROUTINE IS INVOKED WHENEVER AN I/O ACCESS IS MADE TO THE FOC
REGISTERS 3F2,3F4,3F5 WHEN POWER IS OFF TO THE FOC. IF THE FDC IS
POWERED ON BY THIS ROUTINE AND THE RETURN ADDRESS-1 IS POINTING TO AN
IN AL,DX OR OUT DX,AL INSTRUCTION, THE RETURN ADDRESS IS ADJUSTED TO
RE-EXECUTE THAT INSTRUCTION UPON NMI EXIT.
EX IT COND I TI ONS:
NORMAL EXIT CONDITIONS: POWER RESTORED TO THE FDC
TRACK COUNTER(S) FOR THE FDC AND ARRAY IN SYNC
NMI'S ENABLED (PORT 77H)
SETUP TO REISSUE THE DISKETTE I/O COMMAND
ERROR EXIT CONDITIONS: NONE
REGISTERS MODIFIED:
AX, BX, CX, DX, ES, AND SI
INTERNAL DATA AREAS / TABLES: BIOS DATA AREA AT SEGMENT 40H
EXTERNAL l Y REFERENCED ROUTINES: REFER TO EXTRN LIST
EXTERNALL Y REF,RENCED DATA AREAS: REFER TO EXTRN LIST
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006F
006F
81 7E OA 03F2
0074 75 14
0076 F6 46 10 04
007A 74 OE
DSKT_RESYNC PROC NEAR
ASSUME CS: ROMCODE
ASSUME DS:DATA,ES:ABSO
CMP DXSAVE[BP] ,DRIVLCNTL
JNE DSKLON
TEST ALSAVE[BP], FDCRUN
JZ DSKLON
CHECK FOR DX = RESET PORT
JUMP IF NOT
RESET BIT ACTIVE IN AL?
YES THEN POWER ON CNTLR
IF NOT A RESET COMMAND TO 3F2H THEN RESET DISKETTE NMI AND EXIT LEVEL
007C BO B2 MOV AL, OSKLNMI +DSKLDEGATE+RD_CNTL +CNTL_SEL
007E
E6 77 OUT DSKLCNTL,AL
0080 OC 40 OR AL,FDCPWR TOGGLE POWER ON THEN OFF TO
0082 E6 77 OUT DSKLCNTL,AL
RESET NMI BUT DO NOT POWER
0084 24 BF
AND AL. NOT FOCPWR
ON CONTROLLER
0086
E6 77
OUT DSKLCNTL,AL
0088
EB C6
JMP NMHLEXIT
EXIT LEVEL
SAVE DISKETTE MOTOR STATE BUT DISABLE DRIVE SELECTS,DMA, INTERRUPTS
ROM BIOS 2-29