title 'console command processor (CCP), ver 2.2' ; ; assembly language version of the cpm console command processor ; ; version 2.2 February, 1980 ; ; copyright (c) 1976, 1977, 1978, 1979, 1980 ; ; Digital Research ; Box 579, Pacific Grove, ; California, 93950 ; false equ 0000h true equ not false testing equ false ;true if testing ; ; if testing org 3400h bdosl equ $+800h ;bdos location else ; org 0e400h ; for RunCPM 60k org 0f400h ; for RunCPM 64k bdosl equ $+800h ;bdos location endif tran equ 100h tranm equ $ ccploc equ $ ; ; ************************************************************* ; * base of ccp contains the following code/data * ; * ccp: jmp ccpstart (start with command) * ; * jmp ccpclear (start, clear command) * ; * ccp+6 127 (max command length) * ; * ccp+7 comlen (command length = 00) * ; * ccp+8 ' ... ' (16 blanks) * ; ************************************************************* ; * Normal entry is at ccp, where the command line given * ; * at ccp+8 is executed automatically (normally a null * ; * command with comlen = 00). An initializing program * ; * can be automatically loaded by storing the command at * ; * ccp+8, with the command length at ccp+7. In this * ; * case, the ccp executes the command before prompting * ; * console for input. Note that the command is exe- * ; * cuted on both warm and cold starts. When the command * ; * line is initialized, a jump to "jmp ccpclear" dis- * ; * ables the automatic command execution. * ; ************************************************************* ; jmp ccpstart ;start ccp with possible initial command jmp ccpclear ;clear the command buffer maxlen: db 127 ;max buffer length comlen: db 0 ;command length (filled in by dos) ; ;command executed initially in comlen non zero combuf: db ' ' ;8 character fill db ' ' ;8 character fill db 'copyright (c) 1979, digital research '; 38 ds 128-($-combuf) ; ; ;total buffer length is 128 characters comaddr:dw combuf ;address of next character to scan staddr: ds 2 ;starting address of current fillfcb request ; diska equ 0004h ;disk address for current disk bdos equ 0005h ;primary bdos entry point buff equ 0080h ;default buffer fcb equ 005ch ;default file control block ; rcharf equ 1 ;read character function pcharf equ 2 ;print character function pbuff equ 9 ;print buffer function rbuff equ 10 ;read buffer function breakf equ 11 ;break key function liftf equ 12 ;lift head function (no operation) initf equ 13 ;initialize bdos function self equ 14 ;select disk function openf equ 15 ;open file function closef equ 16 ;close file function searf equ 17 ;search for file function searnf equ 18 ;search for next file function delf equ 19 ;delete file function dreadf equ 20 ;disk read function dwritf equ 21 ;disk write function makef equ 22 ;file make function renf equ 23 ;rename file function logf equ 24 ;return login vector cself equ 25 ;return current selected drive number dmaf equ 26 ;set dma address userf equ 32 ;set user number ; ;special fcb flags ; rofile equ 9 ;read only file sysfile equ 10 ;system file flag ; ;special characters ; cr equ 13 ;carriage return lf equ 10 ;line feed la equ 5fh ;left arrow eofile equ 1ah ;end of file ; ;utility procedures ; printchar: mov e,a mvi c,pcharf jmp bdos ; printbc: ;print character but save bc registers push b call printchar pop b ret ; crlf: mvi a,cr call printbc mvi a,lf jmp printbc ; blank: mvi a,' ' jmp printbc ; print: ;print string starting at bc until next 00 push b ; entry call crlf pop h ;now print the string prin0: mov a,m ora a rz ;stop on 00 inx h push h ;ready for next call printchar ;charcter printed pop h jmp prin0 ;for another character ; initialize: mvi c,initf jmp bdos ; select: mov e,a mvi c,self jmp bdos ; bdos$inr: call bdos sta dcnt inr a ret ; open: ;open the file given by d,e mvi c,openf jmp bdos$inr ; openc: ;open comfcb xra a sta comrec ;clear next record to read lxi d,comfcb jmp open ; close: ;close the file given by d,e mvi c,closef jmp bdos$inr ; search: ;search for the file given by d,e mvi c,searf jmp bdos$inr ; searchn: ;search for the next occurance of the file mvi c,searnf ; given by d,e jmp bdos$inr ; searchcom: ;search for comfcb file lxi d,comfcb jmp search ; delete: ;delete the fle given by d,e mvi c,delf jmp bdos ; bdos$cond: call bdos ora a ret ; diskread: ;read the next record from the file given mvi c,dreadf ; by d,e jmp bdos$cond ; diskreadc: ;read the comfcb file lxi d,comfcb jmp diskread ; diskwrite: ;write the next record to the file given mvi c,dwritf ; by d,e jmp bdos$cond ; make: ;create the file given by d,e mvi c,makef jmp bdos$inr ; renam: ;rename the file given by d,e mvi c,renf jmp bdos ; getuser: ;return current user code in a mvi e,0ffh ;drop through to setuser ; setuser: mvi c,userf jmp bdos ;sets user number ; saveuser: ;save eser#/disk# before possible ^C or call getuser ; transient; code to a add a add a add a add a ;rotate left lxi h,cdisk ora m ;4b = user, 4b = disk sta diska ;stored away in memory for later ret ; setdiska: lda cdisk sta diska ;user/disk ret ; translate: ;translate character in register a to upper cpi 61h ; case; return if below lower case a rc cpi 7bh ;return if above lower case z rnc ani 5fh ;translated to upper case ret ; readcom: ;read the next command into the command buffer ; check for submit file lda submit ora a jz nosub ; ;scanning a submit file ;change drives to open and read the file lda cdisk ora a mvi a,0 cnz select ;have to open again in case xsub present ; lxi d,subfcb call open jz nosub ;skip if nosub ; lda subrc dcr a ;read last record(s) first sta subcr ;current record to read lxi d,subfcb call diskread ;end of file if last record jnz nosub ; ;disk read is ok, transfer to combuf lxi d,comlen lxi h,buff mvi b,128 call move0 ;line is transfered, close the file with ; a deleted record lxi h,submod mvi m,0 ;clear fwflag inx h dcr m ;one less record lxi d,subfcb call close jz nosub ;close went ok, return to original drive ; lda cdisk ora a cnz select ;print to the 00 lxi h,combuf call prin0 call break$key jz noread call del$sub jmp ccp ;break key depressed ; nosub: call delsub ;translate to upper case, store zero at end call saveuser ;user number save in case ^C mvi c,rbuff lxi d,maxlen call bdos call setdiska ;no control-C do restore diska ; noread: ;enter here from submit file lxi h,comlen ;set the last character to zero for later scans mov b,m ;length is in b ; readcom0: inx h mov a,b ora a ;end of scan jz readcom1 mov a,m ;get character and translate call translate mov m,a dcr b jmp readcom0 ; readcom1: ;end of scan, h,l address end of command mov m,a ;store a zero lxi h,combuf shld comaddr ;ready to scan to zero ret ; break$key: ;check for a character ready at console mvi c,breakf call bdos ora a rz mvi c,rcharf call bdos ;character cleared ora a ret ; cselect: ;get currently selected drive number to reg a mvi c,cself jmp bdos ; setdmabuff: ;set default buffer dma address lxi d,buff ; (drop through) ; setdma: ;set dma address to d,e mvi c,dmaf jmp bdos ; del$sub: ;delete the submit file, and set submit flag lxi h,submit mov a,m ora a rz ;return if no submit file mvi m,0 ;submit flag is set to false xra a call select ;on drive a to erase file lxi d,subfcb call delete lda cdisk jmp select ;back to original drive ; serialize: ;check serialization lxi d,serial lxi h,bdosl mvi b,6 ;check 6 bytes ; ser0: ldax d cmp m jnz badserial inx d inx h dcr b jnz ser0 ret ;serial number is ok ; comerr: ;error in command string starting at call crlf ; position 'staddr' and ending with first lhld staddr ; delimeter, h,l address first to print ; comerr0: ;print characters until blank or zero mov a,m cpi ' ' jz comerr1 ;not blank ora a jz comerr1 ;not 0, so print it push h call printchar pop h inx h jmp comerr0 ;for another character ; comerr1: ;print question mark and delete sub file mvi a,'?' call printchar call crlf call del$sub jmp ccp ;restart with next command ; ;FCB scan and fill subroutine (entry is at ; fillfcb below) ;fill the comfcb, indexed by a (0 or 16) ;subroutines ; delim: ;look for a delimeter ldax d ora a rz ;not the last element cpi ' ' jc comerr ;non graphic rz ;treat blank as delimeter cpi '=' rz cpi la ;left arrow rz cpi '.' ;period rz cpi ':' ;colon rz cpi ';' ;semicolon rz cpi '<' ;left angle bracket rz cpi '>' ;right angle bracket rz ret ;delimeter not found ; deblank: ;deblank the input line ldax d ora a rz ;treat end of line as blank cpi ' ' rnz inx d jmp deblank ; addh: ;add a to h,l add l mov l,a rnc inr h ret ; fillfcb0: ;equivalent to fillfcb(0) mvi a,0 ; fillfcb: lxi h,comfcb call addh push h push h ;fcb rescanned at [?]- xra a sta sdisk ;clear selected disk (in case a:...) lhld comaddr xchg ;command address in d,e call deblank ;to first non blank character xchg shld staddr xchg pop h ;d,e has command, h,l has fcb address ;look for preceding file name a: b: ... ldax d ora a jz setcur0 ;use current disk of empty command ; sbi 'A'-1 mov b,a ;disk name held in b if ':' follows inx d ldax d cpi ':' jz setdsk ;set disk name if : ; setcur: ;set current disk dcx d ;back to first character of command ; setcur0: lda cdisk mov m,a jmp setname ; setdsk: ;set disk to name in register b mov a,b sta sdisk ;mark as disk selected mov m,b inx d ;past the : ; setname: ;set the file name field mvi b,8 ;file name length, (max) ; setnam0: call delim jz padname ;not a delimeter inx h cpi '*' jnz setnam1 ;must be ?'s mvi m,'?' jmp setnam2 ;to dec count ; setnam1: mov m,a ;store character in fcb inx d ; setnam2: dcr b ;coutn down length jnz setnam0 ; ;end of name, truncate remainder tryname: call delim jz setty ;set type field if delimeter inx d jmp tryname ; padname: inx h mvi m,' ' dcr b jnz padname ; setty: ;set the type field mvi b,3 cpi '.' jnz padty ;skip the field if not there inx d ;past the '.', to the type field ; setty0: ;set the field from the command buffer call delim jz padty inx h cpi '*' jnz setty1 ;[only 'se' on listing]- mvi m,'?' ;since * specified jmp setty2 ; setty1: ;not a * so copy to type field mov m,a inx d ; setty2: dcr b jnz setty0 ; ;end of type field, truncate trtyp: ;truncate type field call delim jz efill inx d jmp trtyp ; padty: ;pad the type field with blanks inx h mvi m,' ' dcr b jnz padty ; efill: ;end of filename/filetype fill, save command ; address, fill the remaining fields for the ; fcb mvi b,3 ; efill0: inx h mvi m,0 dcr b jnz efill0 xchg shld comaddr ;set new starting point ; ;recover the start address of the fcb and ;count ?'s pop h lxi b,11 ;b=0, c=8+3 ; scnq: inx h mov a,m cpi '?' jnz scnq0 ;? found, count it in b inr b ; scnq0: dcr c jnz scnq ; ;number of ?'s in c [sic], move to a and mov a,b ;return with flags set ora a ret ; intvec: ;intrinsic function names (all are four db 'DIR ' ; characters) db 'ERA ' db 'TYPE' db 'SAVE' db 'REN ' db 'USER' ; intlen equ ($-intvec)/4 ;intrinsic function length ; serial: db 0,22,0,0,0,0 ; intrinsic: ;look for intrinsic functions (comfcb has ; been filled lxi h,intvec mvi c,0 ;c counts intrinsics as scanned ; intrin0: mov a,c cpi intlen ;done with scan? rnc lxi d,comfcb+1 ;beginning of name mvi b,4 ;length of match is in b ; intrin1: ldax d cmp m ;match jnz intrin2 ;skip if no match inx d inx h dcr b jnz intrin1 ;loop while matching ; ;complete match on name, check for blank in fcb ldax d cpi ' ' jnz intrin3 ;otherwise matched mov a,c ret ;with intrinsic number in a ; intrin2: ;mismatch, move to end of intrinsic inx h dcr b jnz intrin2 ; intrin3: ;try next intrinsic inr c ;to next intrinsic number jmp intrin0 ;for another round ; ccpclear: ;clear the command buffer xra a sta comlen ;drop through to start ccp ; ccpstart: ;enter here from boot loader lxi sp,stack push b ;save initial disk number ;(high order 4 bits = user code, low order ;4 bits = disk #) mov a,c rar rar rar rar ani 0fh ;user code mov e,a call setuser ;user code selected ;initialize for this user, get $ flag call initialize ;0ffh in accum if $ present sta submit ;submit flag set if $ file present pop b ;recall user code and disk number mov a,c ani 0fh ;disk number in accumulator sta cdisk ;clears user code nibble call select ;proper disk is selected, now check sub file ;check for initial command lda comlen ora a jnz ccp0 ;assumed typed already ; ccp: ;enter here on each command or error condition lxi sp,stack call crlf ;print D> where d is disk number call cselect adi 'A' call printchar mvi a,'>' call printchar call readcom ;command buffer filled ; ccp0: ;(enter here from initialization with command ; filled) lxi d,buff call setdma ;default dma address at buff call cselect sta cdisk ;current disk number saved call fillfcb0 ;command fcb filled cnz comerr ;the name cannot be an ambiguous reference lda sdisk ora a jnz userfunc ;check for an intrinsic function ; call intrinsic lxi h,jmptab ;index is in the accumulator mov e,a mvi d,0 dad d dad d ;index in d,e mov a,m inx h mov h,m mov l,a pchl ;pc changes to the proper intrinsic or user ;function jmptab: dw direct ;directory search dw erase ;file erase dw type ;type dw save ;save memory dw rename ;file rename dw user ;user number dw userfunc ;user-defined function ; badserial: lxi h,di or (hlt shl 8) shld ccploc lxi h,ccploc pchl ; ;utility subroutines for intrinsic handlers ; readerr: ;print the read error message lxi b,rdmsg jmp print ; rdmsg: db 'read error',0 ; nofile: ;print no file message lxi b,nofmsg jmp print ; nofmsg: db 'no file',0 ; getnumber: ;read a number from the command line call fillfcb0 ;should be a number lda sdisk ora a jnz comerr ;cannot be prefixed ;convert the byte value in comfcb to binary lxi h,comfcb+1 lxi b,11 ;(b = 0, c = 11) ;value accumulated in b, c counts name length ; to zero conv0: mov a,m cpi ' ' jz conv1 ;more to scan ; inx h sui '0' cpi 10 jnc comerr ;valid? mov d,a mov a,b ;multiply by ten ani 1110$0000b jnz comerr mov a,b rlc rlc rlc ;*8 add b jc comerr add b jc comerr ;*8 + *2 = *10 add d jc comerr ;+digit mov b,a dcr c jnz conv0 ;for another digit ret ; conv1: ;end of digits, check for all blanks mov a,m cpi ' ' jnz comerr ;blanks? inx h dcr c jnz conv1 mov a,b ;recover value ret ; movename: ;move 3 characters from h,l to d,e addresses ; mvi b,3 ; move0: mov a,m stax d inx h inx d dcr b jnz move0 ret ; addhcf: ;buff + a + c to h,l followed by fetch lxi h,buff add c call addh mov a,m ret ; setdisk: ;change disks for this command, if requested xra a sta comfcb ;clear disk name from fcb lda sdisk ora a rz ;no action if not specified dcr a lxi h,cdisk cmp m rz ;already selected jmp select ; resetdisk: ;return to original disk after command lda sdisk ora a rz ;no action if not selected dcr a lxi h,cdisk cmp m rz ;same disk lda cdisk jmp select ; ;individual intrinsics follow direct: ;directory search call fillfcb0 ;comfcb gets file name call setdisk ;change disk drives if requested lxi h,comfcb+1 mov a,m ;may be empty request cpi ' ' jnz dir1 ;skip fill of ??? if not blank ;set comfcb to all ??? for current disk mvi b,11 ;length of fill ????????.??? dir0: mvi m,'?' inx h dcr b jnz dir0 ;not a blank request, must be in comfcb dir1: mvi e,0 push d ;e counts directory entries call searchcom ;first one has been found cz nofile ;not found message dir2: jz endir ;found, but may be system file lda dcnt ;get the location of the element rrc rrc rrc ani 110$0000b mov c,a ;c contains base index into buff for dir entry mvi a,sysfile call addhcf ;value to a ral jc dir6 ;skip if system file ;c holds index into buffer ;another fcb found, new line? pop d mov a,e inr e push d ;e=0,1,2,3,...new line if mod 4 = 0 ani 11b push psw ;and save the test jnz dirhdr0 ;header on current line call crlf push b call cselect pop b ;current disk in a adi 'A' call printbc mvi a,':' call printbc jmp dirhdr1 ;skip current line hdr ; dirhdr0: call blank ;after last one mvi a,':' call printbc ; dirhdr1: call blank ;compute position of name in buffer mvi b,1 ;start with first character of name ; dir3: mov a,b call addhcf ;buff+a+c fetched ani 7FH ;mask flags ;may delete trailing blanks cpi ' ' jnz dir4 ;check for blank type pop psw push psw ;may be 3rd item cpi 3 jnz dirb ;place blank at end if not mvi a,9 call addhcf ;first char of type ani 7fh cpi ' ' jz dir5 ;not a blank in the file type field ; dirb: mvi a,' ' ;restore trailing filename chr dir4: call printbc ;char printed inr b mov a,b cpi 12 jnc dir5 ;check for break between names cpi 9 jnz dir3 ;for another char ;print a blank between names call blank jmp dir3 ; dir5: ;end of current entry pop psw ;discard the directory counter (mod 4) dir6: call break$key ;check for interrupt at keyboard jnz endir ;abort directory search call searchn jmp dir2 ;for another entry ; endir: ;end of directory scan pop d ;discard directory counter jmp retcom ; ; erase: call fillfcb0 ;cannot be all ???'s cpi 11 jnz erasefile ;erasing all of the disk lxi b,ermsg call print call readcom lxi h,comlen dcr m jnz ccp ;pad input inx h mov a,m cpi 'Y' jnz ccp ;ok, erase the entire diskette inx h shld comaddr ;otherwise error at retcom ; erasefile: call setdisk lxi d,comfcb call delete inr a ;255 returned in not found cz nofile ;no file message if so jmp retcom ; ; ermsg: db 'All (Y/N)?',0 ; type: call fillfcb0 jnz comerr ;don't allow ?'s in file name call setdisk call openc ;open the file jz typerr ;zero flag indicates not found ;file opened, real 'til eof call crlf lxi h,bptr mvi m,255 ;read first buffer ; type0: ;loop on bptr lxi h,bptr mov a,m cpi 128 ;end buffer jc type1 push h ;carry 1f 0,1,...,127 ;read another buffer full call diskreadc pop h ;recover address of bp jnz typeof ;hard end of file xra a mov m,a ;bptr = 0 ; type1: ;read character at bptr and print inr m ;bptr = bptr + 1 lxi h,buff call addh ;h,l addresses char mov a,m cpi eofile jz retcom call printchar call break$key jnz retcom ;abort if break jmp type0 ;for another character ; typeof: ;end of file, check for errors dcr a jz retcom call readerr ; typerr: call resetdisk jmp comerr ; save: call getnumber ;value to register a push push psw ;save it for later ;should be followed by a flip ;to save the memory ima call fillfcb0 jnz comerr ;cannot be ambiguous call setdisk ;may be a disk change lxi d,comfcb push d call delete ;existing file rem pop d call make ;create a new file on disk jz saverr ;no directory space xra a sta comrec ;clear next record field pop psw ;#pages to write is in a, change to #sectors mov l,a mvi h,0 dad h lxi d,tran ;h,l is sector count, d,e is load address ; save0: ;check for sector count zero mov a,h ora l jz save1 ;may be completed dcx h ;sector count = sector count - 1 push h ;save it for next time around lxi h,128 dad d push h ;next dma address saved call setdma ;current dma address set lxi d,comfcb call diskwrite pop d pop h ;dma address, sector count jnz saverr ;may be disk full case jmp save0 ;for another sector ; save1: ;end of dump, close the file lxi d,comfcb call close inr a ;255 becomes 00 if error jnz retsave ;for another command ; saverr: ;must be full or head only disk lxi b,fullmsg call print ; retsave: ;reset dma buffer call setdmabuff jmp retcom ; fullmsg: db 'no space',0 ; ; rename: ;rename a file on a specific disk call fillfcb0 jnz comerr ;must be unambiguous lda sdisk push psw ;save for later compare call setdisk ;disk selected call searchcom ;is new name already there? jnz renerr3 ;file doesn't exist, move to second half of fcb lxi h,comfcb lxi d,comfcb+16 mvi b,16 call move0 ;check for = or left arrow lhld comaddr xchg call deblank cpi '=' jz ren1 cpi la jnz renerr2 ; ren1: xchg inx h shld comaddr ;past delimiter ;proper delimiter found call fillfcb0 jnz renerr2 ;check for dirve conflict pop psw mov b,a ;previous drive number lxi h,sdisk mov a,m ora a jz ren2 ;drive name was specified. same one? cmp b mov m,b jnz renerr2 ; ren2: mov m,b ;store the name in case drives switched xra a sta comfcb call searchcom ;is old file there jz renerr1 ;everything is ok, rename the file lxi d,comfcb call renam jmp retcom ; renerr1: ;no file on disk call nofile jmp retcom ; renerr2: ;ambigous reference/name conflict call resetdisk jmp comerr ; renerr3: ;file already exists lxi b,renmsg call print jmp retcom ; renmsg: db 'file exists',0 ; user: ;set user number call getnumber ;leaves the value in the accumulator cpi 16 jnc comerr ;must be between 0 and 15 mov e,a ;save for setuser call lda comfcb+1 cpi ' ' jz comerr call setuser ;new user number set jmp endcom ; userfunc: call serialize ;check serialization ;load user function and set up for execution lda comfcb+1 cpi ' ' jnz user0 ;no file name, but may be disk switch lda sdisk ora a jz endcom ;no disk name if 0 dcr a sta cdisk call setdiska ;set user/disk call select jmp endcom ; user0: ;file name is present lxi d,comfcb+9 ldax d cpi ' ' jnz comerr ;type ' push d call setdisk pop d lxi h,comtype ;.com call movename ;file type is set to .com call openc jz userer ;file opened properly, read it into memory lxi h,tran ;transient program base ; load0: push h ;save dma address xchg call setdma lxi d,comfcb call diskread jnz load1 ;sector loaded, set new dma address and com pop h lxi d,128 dad d lxi d,tranm ;has the load overflowed? mov a,l sub e mov a,h sbb d jnc loaderr jmp load0 ;for another sector ; load1: pop h dcr a jnz loaderr ;end file is 1 call resetdisk ;back to original disk call fillfcb0 lxi h,sdisk push h mov a,m sta comfcb ;drive number set mvi a,16 call fillfcb ;move entire fct to pop h mov a,m sta comfcb+16 xra a sta comrec ;record number set to zero lxi d,fcb lxi h,comfcb mvi b,33 call move0 ;move command line to buff lxi h,combuf ; bmove0: mov a,m ora a jz bmove1 cpi ' ' jz bmove1 ;[text was truncated, I made it 1] - inx h jmp bmove0 ;for another scan ;first blank position found bmove1: mvi b,0 lxi d,buff+1 ;ready for the move bmove2: mov a,m stax d ora a jz bmove3 ;more to move inr b inx h inx d jmp bmove2 ; bmove3: ;b has character count mov a,b sta buff call crlf ;now go to the loaded program call setdmabuff ;default dma call saveuser ;user code saved ;low memory diska contains user code call tran ;gone to the loaded program lxi sp,stack ;may come back here call setdiska call select jmp ccp ; userer: ;arrive here on command error call resetdisk jmp comerr ; loaderr: ;cannot load the program lxi b,loadmsg call print jmp retcom ; loadmsg: db 'bad load',0 ; comtype: db 'com' ;for com files ; ; retcom: ;reset disk before end of command check call resetdisk ; endcom: ;end of intrinsic command call fillfcb0 ;to check for garbage at end of line lda comfcb+1 sui ' ' lxi h,sdisk ora m ;0 in accumulator if no disk selected, ;and blank fcb jnz comerr jmp ccp ; ; ; data areas ; ds 16 ;8 level stack stack: ; ; 'submit' file control block ; submit: db 0 ;00 if no submit file, ff if submitting subfcb: db 0,'$$$ ' ;file name is $$$ db 'sub',0,0 ;file name is sub submod: db 0 ;module number subrc: ds 1 ;record count filed ds 16 ;disk map subcr: ds 1 ;current record to read ; ; command file control block ; comfcb: ds 32 ;fields filled in later comrec: ds 1 ;current record to read/write dcnt: ds 1 ;disk directory count (used for error codes) cdisk: ds 1 ;current disk sdisk: ds 1 ;selected disk for current operation ;none=0, a=1, b=2 ... bptr: ds 1 ;buffer pointer ; end ccploc