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MPM OPERATING SYSTEMS/MPM-86/MPM-86 2.0 SOURCES/04/LBDOSDAT.A86

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+;******************* BDOS data area ********************
+;
+;
+;       8086 variables that must recide in code segment
+;
+cseg    $
+;
+axsave                  dw      0       ; register saves
+SS_save                 dw      0
+SP_save                 dw      0
+;
+;       Variables in data segment:
+;
+dseg    cpmsegment
+        org     bdosoffset+bdoscodesize
+;
+;       byte I/O variables:
+;
+compcol db      0               ;true if computing column position
+strtcol db      0               ;starting column position after read
+column  db      0               ;column position
+listcp  db      0               ;listing toggle
+kbchar  db      0               ;initial key char = 00
+;
+;       common values shared between bdosi and bdos
+;
+usrcode db      0                       ;current user number
+curdsk  db      0                       ;current disk number
+info    dw      0                       ;information address
+aret    dw      0                       ;address value to return
+lret    EQU     byte ptr aret           ;low(aret)
+;
+;       data areas for file system:
+;
+;       initialized data
+;
+efcb    db      empty           ;0e5=available dir entry
+rodsk   dw      0               ;read only disk vector
+dlog    dw      0               ;logged-in disks
+dmaad   dw      0               ;dma address
+;
+;       curtrka - alloca are set upon disk select
+;       (data must be adjacent, do not insert variables)
+;       (address of translate vector, not used)
+;
+cdrmaxa dw      0               ;pointer to cur dir max value
+curtrka dw      0               ;current track address
+curreca dw      0               ;current record address
+buffa   dw      0               ;pointer to directory dma address
+dpbaddr dw      0               ;current disk parameter block address
+checka  dw      0               ;current checksum vector address
+alloca  dw      0               ;current allocation vector address
+addlist EQU     8               ;"$-buffa" = address list size
+;
+;       sectpt - offset obtained from disk parm block at dpbaddr
+;       (data must be adjacent, do not insert variables)
+sectpt  dw      0               ;sectors per track
+blkshf  db      0               ;block shift factor
+blkmsk  db      0               ;block mask
+extmsk  db      0               ;extent mask
+maxall  dw      0               ;maximum allocation number
+dirmax  dw      0               ;largest directory number
+dirblk  dw      0               ;reserved allocation bits for direct.
+chksiz  dw      0               ;size of checksum vector
+offsetv dw      0               ;offset tracks at beginning
+endlist rs      0               ;end of list
+dpblist equ     (offset endlist)-(offset sectpt)        ;size
+;
+;       local variables
+tranv   dw      0               ;address of translate vector
+fcbcopied  db   0               ;set true if copy$fcb called
+rmf     db      0               ;read mode flag for open$reel
+dirloc  db      0               ;directory flag in rename, etc.
+seqio   db      0               ;1 if sequential i/o
+linfo   db      0               ;low(info)
+dminx   db      0               ;local for diskwrite
+srchl   db      0               ;search length
+srcha   dw      0               ;search address
+tinfo   dw      0               ;temp for info in "make"
+single  db      0               ;set true if single byte 
+                                ;allocation map
+resel   db      0               ;reselection flag
+olddsk  db      0               ;disk on entry to bdos
+fcbdsk  db      0               ;disk named in fcb
+rcount  db      0               ;record count in current fcb
+extval  db      0               ;extent number and extmsk
+vrecord dw      0               ;current virtual record
+lvrecord equ    byte ptr vrecord ;low (vrecord)
+arecord dw      0               ;current actual record
+ablock  dw      0               ;current actual block# * blkmsk
+;
+;       local variables for directory access
+dptr    db      0               ;directory pointer 0,1,2,3
+dcnt    dw      0               ;directory counter 0,1,...,dirmax
+ldcnt   equ     byte ptr dcnt   ;low(dcnt)
+drec    dw      0               ;directory record 0,1,...,dirmax/4
+;
+;       Special 8086 variables:
+;
+ioloc           db      0       ;iobyte
+dmabase         dw      0       ;segment base for disk I/O
+infosave        dw      0       ;save for FCB address
+parametersegment dw     0       ;user parameter segment
+parcopfl        db      0       ;true if parameter block copied
+parlg           db      0       ;length of parameter block
+nallocmem       db      0       ;no. of allocated memory segments
+ncrmem          db      0       ;no. of available memory segments
+crmem           dw      0,0     ;memory table (16 elements)
+                dw      0,0,0,0,0,0
+                dw      0,0,0,0,0,0,0,0
+                dw      0,0,0,0,0,0,0,0
+                dw      0,0,0,0,0,0,0,0
+;
+;
+;       error messages
+;
+dskmsg  db      'Bdos Err On '
+dskerr  db      ' : $'                  ;filled in by errflg
+permsg  db      'Bad Sector$'
+selmsg  db      'Select$'
+rofmsg  db      'File '
+rodmsg  db      'R/O$'
+;
+;       Local buffer area:
+;
+loc_par_area    rb      258     ;local user parameter (FCB,...)
+stackarea       rw      ssize   ;stack size
+endstack        rb      0       ;top of stack
+;
+;******************** end BDOS data area *******************
+end
+