From 2d04cacc5322951f187bb17e017c12920ac8ebe2 Mon Sep 17 00:00:00 2001 From: Mark Zbikowski Date: Thu, 25 Apr 2024 21:24:10 +0100 Subject: MZ is back! --- v4.0/src/BIOS/MSHARD.ASM | 427 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 427 insertions(+) create mode 100644 v4.0/src/BIOS/MSHARD.ASM (limited to 'v4.0/src/BIOS/MSHARD.ASM') diff --git a/v4.0/src/BIOS/MSHARD.ASM b/v4.0/src/BIOS/MSHARD.ASM new file mode 100644 index 0000000..51c0dc8 --- /dev/null +++ b/v4.0/src/BIOS/MSHARD.ASM @@ -0,0 +1,427 @@ +;*** +; Title: Disk +; C: (C) Copyright 1988 by Microsoft corp. +; Date: 1/11/85 +; +; There is a bug in some versions of IBM's AT ROM BIOS. +; Interrupts are not disabled during read operations. +; +; Use: This program should be chained in line with the disk +; interupt 13h, it intercepts read calls to the hard disk +; and handles them appropriately. For other functions it +; passes controll to OLD13, which should contain the +; address of the AT ROM disk routine. The entry point for +; this program is IBM_DISK_IO. +; + + + .286c ;Use 80286 non-protected mode + +BIOSEG = 040h ;Segment for ROM BIOS Data +ROMSEG = 0F000h ;Segment of ROM + + +BAD_DISK = 01 + +HF_PORT = 01F0h +HF_REG_PORT = 03F6h + +;* Offsets into Fixed disk parameter table +FDP_PRECOMP = 5 +FDP_CONTROL = 8 + +DATA SEGMENT AT BIOSEG ;ROM BIOS data segment + + ORG 42h +CMD_BLOCK DB 6 DUP (?) + +;* Offsets into CMD_BLOCK for registers +PRE_COMP = 0 ;Write Pre-compensation +SEC_CNT = 1 ;Sector count +SEC_NUM = 2 ;Sector number +CYL_LOW = 3 ;Cylinder number, low part +CYL_HIGH = 4 ;Cylinder number, high part +DRV_HEAD = 5 ;Drive/Head (Bit 7 = ECC mode, Bit 5 = 512 byte sectors, + ; Bit 4 = drive number, Bits 3-0 have head number) +CMD_REG = 6 ;Command register + + + ORG 074h + +DISK_STATUS1 DB ? +HF_NUM DB ? +CONTROL_BYTE DB ? + +DATA ENDS + + + +;*** Define where the ROM routines are actually located +ROM SEGMENT AT ROMSEG + + ORG 02E1Eh +ROMCOMMAND PROC FAR +ROMCOMMAND ENDP + + ORG 02E7Fh +ROMWAIT PROC FAR +ROMWAIT ENDP + + ORG 02EE2h +ROMWAIT_DRQ PROC FAR +ROMWAIT_DRQ ENDP + + ORG 02EF8h +ROMCHECK_STATUS PROC FAR +ROMCHECK_STATUS ENDP + + ORG 02F69h +ROMCHECK_DMA PROC FAR +ROMCHECK_DMA ENDP + + ORG 02F8Eh +ROMGET_VEC PROC FAR +ROMGET_VEC ENDP + + ORG 0FF65h +ROMFRET PROC FAR ;Far return at F000:FF65 in AT ROM. +ROMFRET ENDP + +ROM ENDS + + +CODE SEGMENT BYTE PUBLIC 'code' + +EXTRN OLD13:DWORD ;Link to AT bios int 13h + +PUBLIC IBM_DISK_IO + + + ASSUME CS:CODE + ASSUME DS:DATA + + +;*** IBM_DISK_IO - main routine, fixes AT ROM bug +; +; ENTRY: (AH) = function, 02 or 0A for read. +; (DL) = drive number (80h or 81h). +; (DH) = head number. +; (CH) = cylinder number. +; (CL) = Sector number (high 2 bits has cylinder number). +; (AL) = number of sectors. +; (ES:BX) = address of read buffer. +; For more on register contents see ROM BIOS listing. +; Stack set up for return by an IRET. +; +; EXIT: (AH) = status of current operation. +; (CY) = 1 IF failed, 0 if successful. +; For other register contents see ROM BIOS listing. +; +; USES: +; +; +; WARNING: Uses OLD13 vector for non-read calls. +; Does direct calls to the AT ROM. +; Does segment arithmatic. +; +; EFFECTS: Performs DISK I/O operation. +; +IBM_DISK_IO PROC FAR + CMP DL, 80h + JB ATD1 ;Pass through floppy disk calls. + CMP AH, 02 + JE ATD2 ;Intercept call 02 (read sectors). + CMP AH, 0Ah + JE ATD2 ;and call 0Ah (read long). +ATD1: + JMP OLD13 ;Use ROM INT 13h handler. +ATD2: + PUSH BX + PUSH CX + PUSH DX + PUSH DI + PUSH DS + PUSH ES + PUSH AX + MOV AX,BIOSEG ;Establish BIOS segment addressing. + MOV DS,AX + MOV DISK_STATUS1, 0 ;Initially no error code. + AND DL, 07fh ;Mask to hard disk number + CMP DL, HF_NUM + JB ATD3 ;Disk number in range + MOV DISK_STATUS1, BAD_DISK + JMP SHORT ATD4 ;Disk number out of range error, return + +ATD3: + PUSH BX + MOV AX, ES ;Make ES:BX to Seg:000x form. + SHR BX, 4 + ADD AX, BX + MOV ES, AX + POP BX + AND BX,000Fh + PUSH CS + CALL CHECK_DMA + JC ATD4 ;Abort if DMA across segment boundary + + POP AX ;Restore AX register for SETCMD + PUSH AX + CALL SETCMD ;Set up command block for disk op + MOV DX, HF_REG_PORT + OUT DX, AL ;Write out command modifier + CALL DOCMD ;Carry out command +ATD4: +;; Old code - Carry cleared after set by logical or opearation +;; POP AX +;; MOV AH,DISK_STATUS1 ;On return AH has error code +;; STC +;; OR AH,AH +;; JNZ ATD5 ;Carry set if error +;; CLC +;;--------------------------------------------------- +;; New Code - Let Logical or clear carry and then set carry if ah!=0 +;; And save a couple bytes while were at it. + POP AX + MOV AH,DISK_STATUS1 ;On return AH has error code + OR AH,AH + JZ ATD5 ;Carry set if error + STC + +ATD5: + POP ES + POP DS + POP DI + POP DX + POP CX + POP BX + RET 2 ;Far return, dropping flags +IBM_DISK_IO ENDP + + + +;*** SETCMD - Set up CMD_BLOCK for the disk operation +; +; ENTRY: (DS) = BIOS Data segment. +; (ES:BX) in seg:000x form. +; Other registers as in INT 13h call +; +; EXIT: CMD_BLOCK set up for disk read call. +; CONTROL_BYTE set up for disk operation. +; (AL) = Control byte modifier +; +; +; Sets the fields of CMD_BLOCK using the register contents +; and the contents of the disk parameter block for the given drive. +; +; WARNING: (AX) destroyed. +; Does direct calls to the AT ROM. +; +SETCMD PROC NEAR + MOV CMD_BLOCK[SEC_CNT], AL + MOV CMD_BLOCK[CMD_REG], 020h ;Assume function 02 + CMP AH, 2 + JE SETC1 ;CMD_REG = 20h if function 02 (read) + MOV CMD_BLOCK[CMD_REG], 022h ;CMD_REG = 22h if function 0A (" long) +SETC1: ;No longer need value in AX + MOV AL, CL + AND AL, 03fh ;Mask to sector number + MOV CMD_BLOCK[SEC_NUM], AL + MOV CMD_BLOCK[CYL_LOW], CH + MOV AL, CL + SHR AL, 6 ;Get two high bits of cylender number + MOV CMD_BLOCK[CYL_HIGH], AL + MOV AX, DX + SHL AL, 4 ;Drive number + AND AH, 0Fh + OR AL, AH ;Head number + OR AL, 0A0h ;Set ECC and 512 bytes per sector + MOV CMD_BLOCK[DRV_HEAD], AL + PUSH ES ;GET_VEC destroys ES:BX + PUSH BX + PUSH CS + CALL GET_VEC + MOV AX, ES:FDP_PRECOMP[BX] ;Write pre-comp from disk parameters + SHR AX, 2 + MOV CMD_BLOCK[PRE_COMP],AL ;Only use low part + MOV AL, ES:FDP_CONTROL[BX] ;Control byte modifier + POP BX + POP ES + MOV AH, CONTROL_BYTE + AND AH, 0C0h ;Keep disable retry bits + OR AH, AL + MOV CONTROL_BYTE, AH + RET +SETCMD ENDP + + + +;*** DOCMD - Carry out READ operation to AT hard disk +; +; ENTRY: (ES:BX) = address for read in data. +; CMD_BLOCK set up for disk read. +; +; EXIT: Buffer at (ES:BX) contains data read. +; DISK_STATUS1 set to error code (0 if success). +; +; +; +; WARNING: (AX), (BL), (CX), (DX), (DI) destroyed. +; No check is made for DMA boundary overrun. +; +; EFFECTS: Programs disk controller. +; Performs disk input. +; +DOCMD PROC NEAR + MOV DI, BX ;(ES:DI) = data buffer addr. + PUSH CS + CALL COMMAND + JNZ DOC3 +DOC1: + PUSH CS + CALL WAITT ;Wait for controller to complete read + JNZ DOC3 + MOV CX, 100h ;256 words per sector + MOV DX, HF_PORT + CLD ;String op goes up + CLI ;Disable interrupts (BUG WAS FORGETTING THIS) + REPZ INSW ;Read in sector + STI + TEST CMD_BLOCK[CMD_REG], 02 + JZ DOC2 ;No ECC bytes to read. + PUSH CS + CALL WAIT_DRQ + JC DOC3 + MOV CX, 4 ;4 bytes of ECC + MOV DX, HF_PORT + CLI + REPZ INSB ;Read in ECC + STI +DOC2: + PUSH CS + CALL CHECK_STATUS + JNZ DOC3 ;Operation failed + DEC CMD_BLOCK[SEC_CNT] + JNZ DOC1 ;Loop while more sectors to read +DOC3: + RET +DOCMD ENDP + + + +;*** GET_VEC - Get pointer to hard disk parameters. +; +; ENTRY: (DL) = Low bit has hard disk number (0 or 1). +; +; EXIT: (ES:BX) = address of disk parameters table. +; +; USES: AX for segment computation. +; +; Loads ES:BX from interrupt table in low memory, vector 46h (disk 0) +; or 70h (disk 1). +; +; WARNING: (AX) destroyed. +; This does a direct call to the AT ROM. +; +GET_VEC PROC NEAR + PUSH OFFSET ROMFRET + JMP ROMGET_VEC +GET_VEC ENDP + + + +;*** COMMAND - Send contents of CMD_BLOCK to disk controller. +; +; ENTRY: Control_byte +; CMD_BLOCK - set up with values for hard disk controller. +; +; EXIT: DISK_STATUS1 = Error code. +; NZ if error, ZR for no error. +; +; +; WARNING: (AX), (CX), (DX) destroyed. +; Does a direct call to the AT ROM. +; +; EFFECTS: Programs disk controller. +; +COMMAND PROC NEAR + PUSH OFFSET ROMFRET + JMP ROMCOMMAND +COMMAND ENDP + + + +;*** WAITT - Wait for disk interrupt +; +; ENTRY: Nothing. +; +; EXIT: DISK_STATUS1 = Error code. +; NZ if error, ZR if no error. +; +; +; WARNING: (AX), (BL), (CX) destroyed. +; Does a direct call to the AT ROM. +; +; EFFECTS: Calls int 15h, function 9000h. +; +WAITT PROC NEAR + PUSH OFFSET ROMFRET + JMP ROMWAIT +WAITT ENDP + + + +;*** WAIT_DRQ - Wait for data request. +; +; ENTRY: Nothing. +; +; EXIT: DISK_STATUS1 = Error code. +; CY if error, NC if no error. +; +; +; WARNING: (AL), (CX), (DX) destroyed. +; Does a direct call to the AT ROM. +; +WAIT_DRQ PROC NEAR + PUSH OFFSET ROMFRET + JMP ROMWAIT_DRQ +WAIT_DRQ ENDP + + + +;*** CHECK_STATUS - Check hard disk status. +; +; ENTRY: Nothing. +; +; EXIT: DISK_STATUS1 = Error code. +; NZ if error, ZR if no error. +; +; +; WARNING: (AX), (CX), (DX) destroyed. +; Does a direct call to the AT ROM. +; +CHECK_STATUS PROC NEAR + PUSH OFFSET ROMFRET + JMP ROMCHECK_STATUS +CHECK_STATUS ENDP + + + +;*** CHECK_DMA - check for DMA overrun 64k segment. +; +; ENTRY: (ES:BX) = addr. of memory buffer in seg:000x form. +; CMD_BLOCK set up for operation. +; +; EXIT: DISK_STATUS1 - Error code. +; CY if error, NC if no error. +; +; +; WARNING: Does a direct call to the AT ROM. +; +CHECK_DMA PROC NEAR + PUSH OFFSET ROMFRET + JMP ROMCHECK_DMA +CHECK_DMA ENDP + + +CODE ENDS + END -- cgit v1.2.3