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https://github.com/microsoft/MS-DOS.git
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342 lines
11 KiB
NASM
342 lines
11 KiB
NASM
SUBTTL Initialized data and data used at DOS initialization
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PAGE
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; DATA AREA for MS-DOS
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IFNDEF KANJI
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KANJI EQU 0 ;FALSE
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ENDIF
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CONSTANTS SEGMENT BYTE PUBLIC 'CONST'
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EXTRN international_table:BYTE
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EXTRN Current_Country:WORD
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ORG 0
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CONSTRT EQU $ ; Start of constants segment
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PUBLIC DevStrLen
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DEVSTRLEN DB 3 ; Size of below
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PUBLIC DevString
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DEVSTRING DB "DEV" ; Dummy device directory
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;
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; Table of routines for assignable devices
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;
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; MSDOS allows assignment if the following standard devices:
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; stdin (usually CON input)
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; stdout (usually CON output)
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; auxin (usually AUX input)
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; auxout (usually AUX output)
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; stdlpt (usually PRN output)
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;
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; SPECIAL NOTE:
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; Status of a file is a strange idea. We choose to handle it in this manner:
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; If we're not at end-of-file, then we always say that we have a character.
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; Otherwise, we return ^Z as the character and set the ZERO flag. In this
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; manner we can support program written under the old DOS (they use ^Z as EOF
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; on devices) and programs written under the new DOS (they use the ZERO flag
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; as EOF).
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; Default FCBs for boot up
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sftabl LABEL DWORD ; file table
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DW -1
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DW -1
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DW sf_default_number ; Number of entries in table
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DB sf_default_number DUP ( (SIZE sf_entry) DUP (0))
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I_AM NoSetDir,BYTE ; true -> do not set directory
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I_am DidCTRLC,BYTE ; true -> we did a ^C exit
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I_am SpaceFlag,BYTE ; true -> embedded spaces are allowed
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; in FCB
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; the next two variables relate to the position of the logical stdout/stdin
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; cursor. They are only meaningful when stdin/stdout are assigned to the
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; console.
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i_am CARPOS,BYTE ; cursor position in stdin
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i_am STARTPOS,BYTE ; position of cursor at beginning
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; of buffered input call
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I_AM PFLAG,BYTE
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I_AM VERFLG,BYTE ; Initialize with verify off
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I_AM CONTPOS,WORD
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PUBLIC CHARCO
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CHARCO DB 00000011B ; Allows statchks every 4 chars...
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I_AM DMAADD,DWORD ; User's disk transfer address
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; (disp/seg)
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ORG $-CONSTRT-4
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DW 80H
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DW ?
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ENDMEM DW ?
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PUBLIC switch_character
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switch_character DB '/'
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PUBLIC device_availability
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device_availability DB 0FFH
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I_AM FirstArena,WORD ; first free block found
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I_AM BestArena,WORD ; best free block found
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I_AM LastArena,WORD ; last free block found
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I_AM AllocMethod,BYTE ; how to alloc first(best)last
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I_AM arena_head,WORD
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; The following block of data is used by SYSINIT. Do not change the order or
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; size of this block
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PUBLIC SYSINITVAR
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SYSINITVAR LABEL WORD
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I_AM DPBHEAD,DWORD ; Pointer to head of DPB-FAT list
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I_AM sft_addr,DWORD ; Pointer to first FCB table
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ORG $-CONSTRT-4
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short_addr sftabl
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DW ? ; DOS segment set at INIT
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; The following address points to the CLOCK device
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i_am BCLOCK,DWORD
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; The following address is used by DISKSTATCHK it is always points to the
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; console input device header
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I_AM BCON,DWORD ; Console device entry points
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i_am NUMIO,BYTE ; Number of disk tables
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MAXSEC DW 0 ; Maximum allowed sector size
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I_AM BUFFHEAD,DWORD ; Pointer to head of buffer queue
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DEVHEAD LABEL DWORD
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I_AM NULDEV,DWORD ; Set to list start passed by
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; BIOS at DOS Init
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DW DEVTYP OR ISNULL
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short_addr SNULDEV
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short_addr INULDEV
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DB "NUL "
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i_am DAY,BYTE
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i_am MONTH,BYTE
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i_am YEAR,WORD
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i_am DAYCNT,WORD
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i_am WEEKDAY,BYTE
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ORG $-CONSTRT-7
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DB 0,0
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DW 0,-1
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DB 0
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I_AM CURDRV,BYTE ; Default to drive A
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I_AM LASTENT,WORD
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i_am INDOS,BYTE ; DOS status for interrupt processing
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ORG $-CONSTRT-1
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DB 0
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I_AM ErrorMode,BYTE ; Flag for INT 24 processing
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PUBLIC WPErr
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WPERR DB -1 ; Write protect error flag
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I_AM CONSWAP,BYTE
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PUBLIC IDLEINT
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IDLEINT DB 1
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PUBLIC CNTCFLAG
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CNTCFLAG DB 0 ; ^C check in dispatch disabled
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PUBLIC LastBuffer
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LASTBUFFER LABEL DWORD ; Buffer queue recency pointer
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DW -1
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DW -1
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; Combination of all device call parameters
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PUBLIC DEVCALL
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DEVCALL SRHEAD <>
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CALLUNIT LABEL BYTE
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CALLFLSH LABEL WORD
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I_AM CALLMED,BYTE
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CALLBR LABEL DWORD
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PUBLIC CALLXAD
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CALLXAD LABEL DWORD
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I_AM CALLRBYT,BYTE
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DB 3 DUP(?)
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PUBLIC CallBPB
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CALLBPB LABEL DWORD
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I_AM CALLSCNT,WORD
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CALLSSEC DW ?
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I_AM CALLDEVAD,DWORD ; stash for device entry point
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; Same as above for I/O calls
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PUBLIC IOCall
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IOCALL SRHEAD <>
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IOFLSH LABEL WORD
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PUBLIC IORCHR
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IORCHR LABEL BYTE
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I_AM IOMED,BYTE
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I_AM IOXAD,DWORD
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I_AM IOSCNT,WORD
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I_AM IOSSEC,WORD
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; Call struct for DSKSTATCHK
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PUBLIC DSKSTCALL
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DSKSTCALL DB DRDNDHL
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DB 0
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PUBLIC DSKSTCOM
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DSKSTCOM DB DEVRDND
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I_AM DSKSTST,WORD
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DB 8 DUP (0)
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I_AM DSKCHRET,BYTE
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short_addr DEVIOBUF
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DW ? ; DOS segment set at Init
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PUBLIC DSKSTCNT
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DSKSTCNT DW 1
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DW 0
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; Days in year
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i_am YRTAB,8
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ORG $-CONSTRT-8
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DB 200,166 ; Leap year
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DB 200,165
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DB 200,165
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DB 200,165
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; Days of each month
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i_am MONTAB,12
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ORG $-CONSTRT-12
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DB 31 ; January
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DB 28 ; February--reset each
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; time year changes
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DB 31 ; March
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DB 30 ; April
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DB 31 ; May
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DB 30 ; June
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DB 31 ; July
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DB 31 ; August
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DB 30 ; September
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DB 31 ; October
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DB 30 ; November
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DB 31 ; December
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IF NOT IBM
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PUBLIC OEM_HANDLER
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OEM_HANDLER DD -1
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ENDIF
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;WARNING For HIGHMEM version, these two vars must be at the end of the
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; Constants segment to prevent them getting overwritten.
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I_AM CurrentPDB,WORD
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i_am CreatePDB,BYTE ; flag for creating a process
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PUBLIC LEAVEADDR
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LEAVEADDR LABEL WORD
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short_addr LEAVE
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CONSTANTS ENDS
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SUBTTL Uninitialized data overlayed by initialization code
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PAGE
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DATA SEGMENT WORD PUBLIC 'DATA'
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; Init code overlaps with data area below
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ORG 0
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i_am INBUF,128
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I_AM CONBUF,131 ; The rest of INBUF and console buffer
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i_am TIMEBUF,6
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I_AM DEVIOBUF,2 ; Buffer for I/O under file assignment
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I_AM EXITHOLD,DWORD
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PUBLIC DevFCB
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DEVFCB LABEL BYTE ; Uses NAME1, NAME2, NAME3 combined
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; WARNING.. do not alter size or relative location of the following 4 items
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; without first examining FCB_RENAME
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I_AM NAME1,12 ; File name buffer
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I_AM ATTRIB,BYTE
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I_AM NAME2,13
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I_AM NAME3,14
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I_AM EXTFCB,BYTE
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; WARNING - the following two items are accessed as a word
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I_AM CREATING,BYTE
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I_AM DELALL,BYTE
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I_AM FoundDel,BYTE
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I_AM user_SP,WORD
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I_AM user_SS,WORD
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I_AM CONTSTK,WORD
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I_AM SECCLUSPOS,BYTE ; Position of first sector
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; within cluster
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I_AM DSKERR,BYTE
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I_AM TRANS,BYTE
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I_AM READOP,BYTE
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I_AM THISDRV,BYTE
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I_AM THISDPB,DWORD
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I_AM CLUSFAC,BYTE
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; WARNING - the following two items are accessed as a word
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I_AM DRIVESPEC,BYTE
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I_AM ROOTSTART,BYTE
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I_AM CLUSSPLIT,BYTE
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i_am INSMODE,BYTE
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I_AM CLUSSAVE,WORD
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I_AM CLUSSEC,WORD
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I_AM PREREAD,WORD ; 0 means preread; 1 means optional
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I_AM FATBYT,WORD
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I_AM DEVPT,DWORD
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I_AM THISFCB,DWORD ; Address of user FCB
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I_AM NEXTADD,WORD
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I_AM RECPOS,4
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I_AM RECCNT,WORD
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I_AM LASTPOS,WORD
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I_AM CLUSNUM,WORD
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I_AM DIRSEC,WORD
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I_AM DIRSTART,WORD
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I_AM SECPOS,WORD ; Position of first sector accessed
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I_AM VALSEC,WORD ; Number of valid (previously written)
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; sectors
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I_AM BYTSECPOS,WORD ; Position of first byte within sector
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I_AM BYTPOS,4 ; Byte position in file of access
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I_AM BYTCNT1,WORD ; No. of bytes in first sector
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I_AM BYTCNT2,WORD ; No. of bytes in last sector
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I_AM SECCNT,WORD ; No. of whole sectors
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I_AM ENTFREE,WORD
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I_AM ENTLAST,WORD
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I_AM NXTCLUSNUM,WORD
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I_AM GROWCNT,DWORD
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I_AM CURBUF,DWORD
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I_AM VOLID,BYTE
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I_AM NULLDEVPT,DWORD
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I_AM CINSAV,DWORD
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I_AM CINDSAV,BYTE
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I_AM COUTDSAV,BYTE
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I_AM COUTSAV,DWORD
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PUBLIC SaveBX
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SaveBX DW ?
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PUBLIC SaveDS
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SaveDS DW ?
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I_AM ConC_spsave,WORD
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I_AM exit_code,WORD ; exit code of last proc.
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I_am exit_type,BYTE ; type of exit...
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IF IBM
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;For 2.00 this pads the DOS so that on a 2 disk IBM PC with no
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;CONFIG.SYS file the space taken up by BIOS, DOS, res COMMAND is
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;about 24K
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IBMPAD DB 540h DUP(?)
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ENDIF
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; make those pushes fast!!!
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EVEN
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DB 0A0H DUP (?)
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I_am AuxStack,0A0h
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I_AM DSKSTACK,0A0h ; Stack space
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PUBLIC IOSTACK
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IOSTACK LABEL BYTE
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PUBLIC NSS
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NSS DW ?
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PUBLIC NSP
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NSP DW ?
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PAGE
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INCLUDE MSINIT.ASM
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