44306A.txt

PAL16L8
JLB 26NOV86
44306A,21G,MMUCTL

CA0 WRITE /DVACC /RT /WCHIM DOUBLE /EMCL /CC2 /WCA GND
LSHADOW /LAPA /EPT /EPMAP /EPTI /EIPL /EIPU /EITPUR /ECD VCC

; MEMORY MANAGEMENT CONTROL

IF (VCC) ECD = WCA * /LSHADOW                   ; DISABLE CACHE ON SHADOW ACCESSES
             + RT * /LSHADOW * /CC2             ; ENABLE WHEN WRITING IN CACHE
                                                ; ENABLE IN THE FIRST PART OF READ/FETCH CYCLES

IF (VCC) LAPA = DVACC * /LSHADOW * /WCHIM       ; LA TO PPN WHEN VIRTUAL ACCESSES ARE DISABLED
                                                ; WE ARE NOT ACCESSING SHADOW MEMORY OR WRITIN
                                                ; CACHE INHIBIT MAP

IF (VCC) EIPUR = /DOUBLE * LSHADOW * WRITE      ; WRITING IN SHADOW IN REX MODE WILL MASK AWAY
                                                ; THE PROTECT BITS

IF (VCC) EIPU = WCHIM                           ; PASS PAGE NUMBER TO BE INHIBITED FROM IDB
              + DOUBLE * LSHADOW * CA0          ; SHADOW ACCESSES IN SEX MODE
              + DOUBLE * LSHADOW * WRITE        ; WRITING IN SHADOW IN SEX MODE WILL WRITE A F
                                                ; BIT PAGE NUMBER

IF (VCC) EIPL = WCHIM                           ; PASS PAGE NUMBER TO BE INHIBITED FROM IDB
              + DOUBLE * LSHADOW * CA0          ; SHADOW ACCESSES IN SEX MODE
              + LSHADOW * WRITE                 ; WRITING LOWER BYTE (SAME FOR REX AND SEX)

IF (VCC) EPTI = LSHADOW * /EMCL * WRITE         ; DISABLE DURING EMCL TO AVOID JAMMING THE IDB
              + LSHADOW * /EMCL * /DOUBLE       ; ENABLE ONLY WHEN IN SHADOW
              + LSHADOW * /EMCL * /CA0          ; DISABLE WHEN IN SEX MODE WE ARE READ/ FETCHIN
                                                ; ADDRESSES. (USE OTHER SRAM BLOCK).

IF (VCC) EPMAP = /WCHIM * /DVACC * /WRITE       ; DISABLE WHEN WRITING THE CACHE INHIBIT MAP
               + /WCHIM * /DVACC * /LSHADOW     ; DISABLE WHEN VIRTUAL ACCESS IS DISABLED AN
               + /WCHIM * /DVACC * /DOUBLE      ; ACCESSING SHADOW MEMORY EITHER.
               + /WCHIM * /DVACC * CA0          ; DISABLE ON SHADOW MEMORY WRITE IN SEX MODE
               + /WCHIM * LSHADOW * /WRITE      ; ADRESSES.
               + /WCHIM * LSHADOW * /DOUBLE
               + /WCHIM * LSHADOW * CA0

IF (VCC) EPT = /WRITE * /EMCL                   ; DISBALE ON EMCL OR
             + /LSHADOW * /EMCL                 ; WRITING IN OTHER HALF
             + /DOUBLE * /EMCL                  ; WHEN IN SEX MODE
             + /CA0 * /EMCL

DESCRIPTION

; 25/2/87 JLB EQUATION FOR EPT MISSING
; 18/5/87 3202B