IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

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EE52: 800£410080 2639 OR oISKETTE_STATUS. TIME_OUT
££57 59 2640 POP CX
EE58 SA 2641 POP OX ; SET ERROR CODE AND RESTORE REGS
EES9 56 2.642 POP AX ; DISCARD THE RETUF!N ADDRESS
EESA F9 2643 STC ; INDICATE ERROR TO CALLER
EES9 C3 2644 Rn
2645
EESC 2646 J25:
EESC 33C9 2647 XOR cx.cx ; RESET THE COUUT
EESE 2648 J26:
EESE EC ~649 IN .u,ox ; GET THE STATUS
EESF AB80 2650 TEST AL.OBOH J IS IT READY
fE61 7504 2651 J"" J27 I YES. GO OUTPUT
fE63 E2F9 2652 LOOP J2. J COUNT omm AHD TRY AGAIN
fE65 EBEB 2653 J"P J2' J ERROR CONDITION
fE67 2654 J2:7: ; OUTPUT
fE67 84C4 2655 t10V AL,AH • GET BYTE TO OUTPUT
E£69 BAF501 2656 ""V DX,03F5H ; DATA PORT
Efbe EE 2657 OUT OX.AL ; OUTPUT THE BYTE
EE60 59 2:658 POP CX ; RECOVER REGISTERS
fE6E 5A 2659 POP OX
EE6F C3 2.660 Rn ; CY = 0 FROM TEST INSTRUCTION
2661 NEt_OUTPUT ENOP
2662 ; -----------------------------------------­
2663 ; GET_PARM
2664 I THIS ROUTINE fETCHES THE IHOEXED POINTER FROM
2665 I THE DISK_BASE BLOCK POINTED AT BY THE DATA
2666 I VAF!IABLE DISK_POINTER
2667 ; A eYTE FROM THAT TABLE IS THEN HOVED INTO AH,
2668 ; THE INDEX OF THAT BYTE BEING THE PARrt IN ex
2669 ; ENTRY -­
2670 BX = INDEX OF BYTE TO BE FETCHED * 2
2671 IF THE lOW BIT OF ex IS ON. THE BYTE IS IMMEDIATELY
2672 OUTPUT TO THE NEC CONTROLLER
2673 EXIT -­
2674 AH = THAT BYTE fROM BLOCK
2675 ; -------------------------------------------­
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EE70 2676 GET_PARl1 PROC t~EAR
E£70 IE 2677 PUSH as SAVE SEGMENT
EE71 2BCO 2678 SUB AX.AX J ZERO TO AX
EE73 8E08 2679 "OV OS,AX
2680 ASSUME OS:ABSO
E£75 C5367800 2681 LOS 51 ,DISK_POINTER ; POINT TO BLOCK
EE79 DIES 2682 SHR ax,l ; DIVIDE BX BY 2. AND SET flAG FOR EXIT
EE7B 8A20 2683 "OV AH,lSI+BXl ; GET THE WORD
EE7D IF 2684 POP OS j RESTORE SEGMENT
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268S ASSUME OS:OATA
EE7E 72C4 2686 JC NEC_OUTPUT ; IF FLAG SET, OUTPUT TO CONTROLLER
EE80 C3 2687 RET ; RETURN TO CALLER
2688 GET_PARI1 ENOP
2689 ;-------------------------------------------­
2690 ; SEEK
2691 THIS ROUTINE WILL MOVE THE HEAD ON THE NAMED DRIVE
2692 TO THE NAMED TRACK. IF THE DRIVE HAS NOT BEEN ACCESSED
2693 SINCE THE DRIVE RESET COMMAND WAS ISSUED, THE DRIVE WILL BE
2694 RECALIBRATED.
2695 ; INPUT
.2:696 (DU = DRrVE TO SEEK ON
2697 (CH) = TRACK TO SEEK TO
2698 ; OUTPUT
2699 CY = 0 SUCCESS
2700 CY = 1 FAILURE -- DISKETTE_STAn../S SET ACCORDINGLY
2701 (AX I DESTROYED
2702 ; ---------------------------------- ---------­
EE81 2703 SEEK PROC HEAR
EE8l· 8001 2704 MV AL,1 ; ESTABLISH MASK fOR RECAL TEST
EE63 51 2705 PUSH CX ; SAVE INPUT VALUES
EE84 8ACA 2706 ""V CL,OL ; GET DRIVE VALUE INTO CL
EE86 D2CO 2707 ROL AL,CL ; SHIFT IT BY THE DRIVE VALUE
EE88 59 2708 POP CX ; RECOVER TRACK VALUE
EE89 84063EOO 2709 TEST AL,SEEK_STATUS ; TEST FOR REeAL REQUIRED
EE8D 7513 2710 JIlZ J2. -; NO_RECAl
EE8F 06063EOO 2711 OR SEEK_STATUS,AL ; TURn ON THE HO RECAL BIT IN FLAG
EE93 6407 2712 "OV AH ,07H i RECALIBRATE COMMAND
EE95 E6ACFF 2713 CALL NEC_OUTPUT
EE98 6AE2 2714- "OV AH,DL
EE9A E6A7FF 2715 CALL tlEC_OUTPUT ; OUTPUT THE DRIVE HUMBER
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