PAL16L8 PAT8032 **-1110-** MK, 84-12-06 DS60 MAIN FUNCTION ENCODER FC2 FC1 AT1 AT0 A23 A22 A17 A16 A08 GND CB7 RAM FPP ERR CDE CD2 CD1 CD0 ACK VCC ;EQUATIONS: IF(VCC) /RAM = /A23*/A22*/CB7 + ;RAM:BOOT OFF /A23*/A22* CB7* A16 ;RAM:BOOT ON IF(VCC) /FPP = FC2*/FC1* A23*/A22* A17*/A16* A08 ;FPP IF(VCC) /ERR = FC1* A23*/A22 + ;EXEC MAPPER FC1* A23* A22*/A08 + ;EXEC I/O /FC2*/FC1* A23* A22*/AT1*/A08 + ;PROT I/O /FC2*/FC1* A23* A22*/AT0*/A08 + ; " /FC2* A23*/A22 ;USER ACC IF(VCC) /ACK = /A23*/A22*/CB7 + ;RAM:BOOT OFF /A23*/A22* CB7* A16 + ;RAM:BOOT ON FC2*/FC1* A23*/A22*/A08 + ;MAPPER FC2*/FC1* A23*/A22*/A17* A16* A08 + ;EDC FC2*/FC1* A23*/A22* A17*/A16* A08 ;FPP IF(VCC) /CD2 = FC2* A23* A22* A17* A16* A08 + ;INTACK FC2*/FC1* A23*/A22* A08 ;CIO, EDC, DMA IF(VCC) /CD1 = FC2* A23* A22* A17* A16* A08 + ;INTACK FC2*/FC1* A23*/A22*/A17* A16* A08 + ;EDC /FC2*/FC1* A23* A22*/A17*/A16* AT1* AT0*/A08 + ;SCC GROUP /FC2*/FC1* A23* A22* A17* AT1* AT0*/A08 + ;4680 GROUP FC2*/FC1* A23* A22*/A17*/A16*/A08 + ;SCCG SYS. FC2*/FC1* A23* A22* A17*/A08 ;4680 SYS IF(VCC) /CD0 = FC2* A23* A22* A17* A16* A08 + ;INTACK FC2*/FC1* A23*/A22*/A17*/A16* A08 + ;CIO /FC2*/FC1* A23* A22*/A17* AT1* AT0*/A08 + ;SCC, MMEM GROUP FC2*/FC1* A23* A22*/A17*/A08 ; " SYS. IF(VCC) /CDE = /A23*/A22* CB7*/A16 + ;BOOT PROM FC2*/FC1* A23*/A22*/A17* A08 + ;EDC OR CIO FC2* A23* A22* A17* A16* A08 + ;INTACK FC2*/FC1* A23*/A22* A17* A16* A08 + ;DMA /FC2*/FC1* A23* A22*/A08* AT1* AT0 + ;8-BIT I/0 FC2*/FC1* A23* A22*/A08 ;8-BIT I/O SYS. FUNCTION TABLE: CB7 FC2 FC1 AT1 AT0 A23 A22 A17 A16 A08 RAM FPP ERR CDE CD2 CD1 CD0 ACK ;C FF AA AA AA A R F E C CCC A ;B CC TT 22 11 0 A P R D DDD C ;7 21 10 32 76 8 M P R E 210 K ----------------------------------- H XX XX LL XH X L H H H HHH L ;RAM - BOOT ON L XX XX LL XX X L H H H HHH L ; " OFF X HL XX HL HL H H L H H LHH L ;FPP X XH XX HL XX X H H L H HHH H ;ERR X XH XX HH XX L H H L H HHH H ; " X LL LX HH XX L H H L H HHH H ; " X LL XL HH XX L H H L H HHH H ; " X LX XX HL XX X H H L H HHH H ; " X HL XX HL XX L H H H H HHH L ;ACK MAPPER X HX XX HH HH H H H H L LLL H ;INTACK X HL XX HL LH H H H H L LLH L ;EDC X HL XX HL LL H H H H L LHL H ;CIO X HL XX HL HH H H H H L LHH H ;DMA X LL HH HH LL L H H H L HLL H ;SCCG X LL HH HH HX L H H H L HLH H ;4680 X LL HH HH LH L H H H L HHL H ;MMG H XX XX LL XL X H H H L HHH H ;BOOT X XX XX LH XX X H H H H HHH H ;EXT ACC X HL XX HH XX L H H H L XXX H ;SYS I/O ACC ----------------------------------- DESCRIPTION: THIS DEVICE PROVIDES DECODED SIGNALS AS WELL AS CODES FOR MOST SYSTEM OPERATIONS. "RAM","FPP","ERR" AND "ACK" ARE DECODED SIGNALS, WHILE "CDE","CD2 - CD0" ARE CODES ADDRESSING EIGHT MAIN SYSTEM DEVICES OR DEVICE GROUPS. AT1 AND AT0 ARE ATTRIBUTE BITS FROM MAPPER WHICH PROVIDE FOLLOWING ACCESS PROTECTION: AT1 AT0 ================ 0 0 READ-ONLY MEMORY ACCESS 0 1 READ/WRITE " " 1 0 NONE " " 1 1 READ/WRITE I/O " THE LOGICAL ADDRESS SPACE IS DIVIDED INTO FOUR MAIN AREAS ENCODED BY ADDRESS BITS A23 AND A22. THE AREAS ARE: A23 A22 ================ 0 0 SYSTEM RAM (ADDRESSED AND PROTECTED BY MAPPER) 0 1 16-BIT EXPANSION (I/O, MEMORY, DMA ETC) 1 0 SYSTEM CONTROL (MAPPER,DMA,CIO,EDC) 1 1 8-BIT I/O DEVICES (PROT. BY MAPPER) WITHIN SYSTEM CONTROL SPACE, MAPPER IS ACCESSED IF A08=0. IF A08=1, ACCESS IS DIRECTED TO CIO (A17=0, A16=0), EDC STATUS REGISTER (A17=0,A16=1) , FLOATING POINT PROCESSOR (A17=1, A16=0) OR DMA (A17=1, A16=1) WIHTIN 8-BIT I/O DEVICE GROUP, ADDRESS BITS A17 AND A16 ARE USED FOR DECODING OF **4680** INTERFACE (A17=1), SERIAL COMM. CHANNELS (A17=0, A16=0) AND MASS MEMORY CHANNELS SUCH AS 5'WINCHESTER INTERFACE, SASI INTERFACE AND FLOPPY INTERFACE. MASS MEMORY GROUP WILL BE ADDRESSED BY A17=0, A16=1. DEVICE OUTPUTS CD2-CD0 ENCODE FOLLOWING: 0 - INTERRUPT ACKNOWLEDGE CYCLE 1 - EDC STATUS ACCESS 2 - CIO ACCESS 3 - DMA " 4 - SCC GROUP ACCESS 5 - 4680 " 6 - MASS MEM. " 7 - BOOT PROM " DEVICE OUTPUT CDE ENABLES OUTPUTS CD2 - CD0, WHEN LOW.