SUBROUTINE USEMEM (ADDR, NBYTES)  
      INTEGER     ADDR, NBYTES  
    
      INTEGER     BITS (16) 
      INTEGER     BIT00,BIT01,BIT02,BIT03,BIT04,BIT05,BIT06,BIT07   
      INTEGER     BIT08,BIT09,BIT10,BIT11,BIT12,BIT13,BIT14,BIT15   
      INTEGER     BIT, BITNO
      COMMON      /BITDFN/ BITS 
      COMMON      /BITDFN/ BIT, BITNO   
      EQUIVALENCE (BITS(1),BIT00),(BITS(2),BIT01),(BITS(3),BIT02)   
      EQUIVALENCE (BITS(4),BIT03),(BITS(5),BIT04),(BITS(6),BIT05)   
      EQUIVALENCE (BITS(7),BIT06),(BITS(8),BIT07),(BITS(9),BIT08)   
      EQUIVALENCE (BITS(10),BIT09),(BITS(11),BIT10) 
      EQUIVALENCE (BITS(12),BIT11),(BITS(13),BIT12) 
      EQUIVALENCE (BITS(14),BIT13),(BITS(15),BIT14) 
      EQUIVALENCE (BITS(16),BIT15)  
    
      INTEGER     DICT (400)
      INTEGER     ID, CID, DTSTRT, DTSTOP   
      COMMON      /DARRAY/ DICT 
      COMMON      /DARRAY/ ID, CID, DTSTRT, DTSTOP  
    
      INTEGER     NSIZE,  NAME(16), NTITLE  
      INTEGER     NFLAGS (512)  
      INTEGER     NADDRS (512)  
      INTEGER     NPOSIT (512)  
      INTEGER     NDATA  (512)  
      INTEGER     NTEXTX (512)  
      INTEGER     NTEXT  (1000) 
      INTEGER     NLX, NLSTRT, NLSTOP   
      INTEGER     TXSTRT, TXSTOP
      INTEGER     NTXBTS
      INTEGER     USEBIT, COMBIT, OVLBIT, EPTBIT
      INTEGER     LDMBIT, MODBIT, MLTBIT, RLSBIT
      INTEGER     GDFBIT, TYPBTS
      INTEGER     ATYPE 
      INTEGER      ICLP07   
      LOGICAL     OLDNAM
      COMMON      /NTABLE/ NSIZE, NAME, NTITLE  
      COMMON      /NTABLE/ NFLAGS, NADDRS, NPOSIT, NDATA, NTEXTX
      COMMON      /NTABLE/ NTEXT
      COMMON      /NTABLE/ NLX, NLSTRT, NLSTOP  
      COMMON      /NTABLE/ TXSTRT, TXSTOP   
      COMMON      /NTABLE/ NTXBTS   
      COMMON      /NTABLE/ USEBIT, COMBIT, OVLBIT, EPTBIT   
      COMMON      /NTABLE/ LDMBIT, MODBIT, MLTBIT, RLSBIT   
      COMMON      /NTABLE/ GDFBIT, TYPBTS   
      COMMON      /NTABLE/ ATYPE
      COMMON      /NTABLE/ ICLP07   
      COMMON      /NTABLE/ OLDNAM   
    
      INTEGER     MEMORY (4096) 
      INTEGER     MEMX  
      INTEGER     MEMLOC
      INTEGER     ROM (64)  
      INTEGER     ONEK, ENDK
      COMMON      /MEMORY/ MEMORY   
      COMMON      /MEMORY/ MEMX 
      COMMON      /MEMORY/ MEMLOC   
      COMMON      /MEMORY/ ROM  
      COMMON      /MEMORY/ ONEK, ENDK   
    
      INTEGER     ECODE 
      INTEGER     CMCHAN
      INTEGER     RBCHAN
      INTEGER     OBCHAN
      INTEGER     MPCHAN
      INTEGER     DBCHAN
      INTEGER     TTYIN 
      INTEGER     TTYOUT
      COMMON      /IODEFN/ ECODE
      COMMON      /IODEFN/ CMCHAN   
      COMMON      /IODEFN/ RBCHAN   
      COMMON      /IODEFN/ OBCHAN   
      COMMON      /IODEFN/ MPCHAN   
      COMMON      /IODEFN/ DBCHAN   
      COMMON      /IODEFN/ TTYIN
      COMMON      /IODEFN/ TTYOUT   
      INTEGER     I 
      LOGICAL     OWRITE
C     WRITE (DBCHAN, 1) ADDR, NBYTES
C    1FORMAT (' ENTER USEMEM WITH', 2I5)
      OWRITE = .FALSE.  
      MEMLOC = ADDR 
      DO  13098 I = 1, NBYTES   
      MEMX = ISHFT (MEMLOC,-4) + 1  
      BITNO = IAND (MEMLOC, 15) + 1 
      BIT = BITS (BITNO)
      IF (.NOT. (IAND(MEMORY(MEMX),BIT).NE.0))GO TO 13100   
    
      IF (.NOT. (.NOT.OWRITE))GO TO 13102   
    
      OWRITE = .TRUE.   
      NLX = DICT (CID)  
      IF (IAND(NFLAGS(NLX),TYPBTS+COMBIT).NE.0) CALL ERROR(11)  
13102 CONTINUE  
    
      GO TO 13101   
13100 CONTINUE  
    
      OWRITE = .FALSE.  
      MEMORY(MEMX) = MEMORY(MEMX) + BIT 
13101 CONTINUE  
    
      ONEK = ISHFT (MEMLOC,-10) + 1 
      IF (.NOT. (ROM(ONEK).EQ.1))GO TO 13104
    
      CALL ERROR (17)   
13104 CONTINUE  
    
      MEMLOC = MEMLOC + 1   
13098 CONTINUE  
    
C     WRITE (DBCHAN, 2) 
C    2FORMAT (' EXIT USEMEM')   
      RETURN
      END