IBM PC CONVERTIBLE Technical Reference page 155

0283 E8 022C R
CALL NELOUTPUT
0286 8A E2
MOV AH,DL
0288 E8 022C R
CALL NELOUTPUT
OUTPUT THE DRIVE NUMBER
0288 E8 0340 R
CALL CHK-STAL2 GET THE INTERUPT AND SENSE INT
STATU~
028E 73 05
JNC
J28 RECAL SUCCESSFUL
0290 E2 EF
LOOP
J27A RETRY I F MORE THAN 77 STEPS NEEDED
0292 58 POP AX
DISCARD ERROR RETURN ADDRESS
0293 EB 59
JMP SHORT J32
SEEK-ERROR
DRIVE IS IN SYNC WITH CONTROLLER, SEEK TO TRACK
0295
J28:
0295 C6 06 0041 R 00 MOV
DISKETTLSTATUS ,0 CLEAR DISKETTE STATUS
029A 80 FA 01
CMP DL ,01 CHECK FOR ABOVE DRIVE
0290 77 20
JA J28_3
CHECK FOR CURRENT TRACK = DESIRED TRACK
029F E4 77
IN AL,DSKLCNTL
02Al A8 80
TEST
AL,DSKLNMI ; IS DISKETTE CONTROL REG CORRECT?
02A3 74 lA
JZ J28_3
; JUMP I F NOT
02A5 50 PUSH AX
02A6 24 E2 AND
AL, DSKLNMI +FDLPWR+DSKLDEGATE+CNTL_SEL ; READ DRI TRK
cn
02A8 80 FA 00 CMP DL,O
02AB 75 02
JNE J28_2
02AD OC 08 OR AL,DRO_TRK-SEL
SET TRACK SENSE FOR DRIVE 0
02AF J28_2 :
02AF E6 77 OUT DSKT _CNTL, AL
SELECT DRIVE # FOR TRACK SENSE
02Bl 8B CF
MOV CX,DI GET TRACK NUMBER IN CH
02B3 E4 77
IN AL,DSKLCNTL READ TRACK POSITION
02B5 3A C5
CMP AL,CH
COMPARE TRACK ON WITH DESIRED TRACK
02B7 58
POP AX
02B8
E6 77 OUT DSKLCNTL, AL RESTORE SENSE REGISTER
02BA 75 03
JNE J28_3
ON SAME TRACK SO JUST EXIT WITH NO ERROR
02BC F8 CLC
02BD EB 2F JMP SHORT
J32 EXIT
02BF B4 OF J28_3: MOV
AH,SEEK-CMD SEEK COMMAND TO NEC
02Cl E8 022C CALL NELOUTPUT
02C4 8A E2 MOV AH,DL
DRIVE NUMBER
02C6 E8 022C R
CALL NELOUTPUT
02C9 8B C7
MOV AX,DI TRACK NUMBER
02CB E8 022C R
CALL NELOUTPUT
02CE 58
POP AX DISCARD ERROR RETURN ADDRESS
02CF
E8 0340 R CALL CHK-STAL2 GET ENDING INTERRUPT AND
;----- WAIT FOR HEAD SETTLE
0202 9C PUSHF SAVE STATUS FLAGS
0203 BB 0012 MOV BX,18
GET HEAD SETTLE PARAMETER
0206 E8 0259 R CALL GELPARM
0209 80 FC OF
CMP AH,15 CHECK FOR AT LEAST 15 MSEC
02DC 73 02
JAE J29 SET IT TO 15 I F NOT = OF ABOVE
02DE B4 OF MOV AH,15
02EO J29 : HEAD_SETTLE
02EO OA E4
OR AH,AH
02E2 74 09
JZ J31 EXIT LOOP IF NO WAIT
02E4 B9 0102
MOV
CX, MS_DELAY
02E7 E2 FE
LOOP
$
02E9 FE CC DEC AH
02E8 EB F3 JMP SHORT J29 DO IT SOME MORE
02ED
J31 :
02ED 9D
POPF
02EE J32 : SEEK-ERROR
02EE 8B CF MOV CX, DI RESTORE CX
02FO C3 RET
RETURN TO CALLER
02Fl SEEK ENDP
2-130 ROM BIOS