PAL20L10                                               PAL DESIGN SPECIFICATION
P7073                                                     COLI/SACKETT 09/14/82
MC6800 MICROPROCESSOR INTERFACE
MMI SUNNYVALE, CALIFORNIA
A15  A14 A13  A12   A11    NC    /S    /R     PH2    VMA  /AR GND
ENIN EN  /IO /RAM4 /RAM3 /RAM2 /RAM1 /PROM2 /PROM1 /RESET VUA VCC


IF(VCC)  PROM1 =  A15* A14* A13* A12     * VMA* PH2*/RESET    ;PROM1, F000-FFFF

IF(VCC)  PROM2 =  A15* A14* A13*/A12     * VMA* PH2*/RESET    ;PROM2, E000-EFFF

IF(VCC)  RAM1  = /A15*/A14*/A13*/A12*/A11* VMA* PH2*/RESET    ;RAM1,  0000-07FF

IF(VCC)  RAM2  = /A15*/A14*/A13*/A12* A11* VMA* PH2*/RESET    ;RAM2,  0800-0FFF

IF(VCC)  RAM3  = /A15*/A14*/A13* A12*/A11* VMA* PH2*/RESET    ;RAM3,  1000-17FF

IF(VCC)  RAM4  = /A15*/A14*/A13* A12* A11* VMA* PH2*/RESET    ;RAM4,  1800-1FFF

IF(VCC)  IO    =  A15* A14*/A13* A12* A11* VMA* PH2*/RESET    ;I/O,   D800-DFFF

IF(VCC) /EN    = /PROM1*/PROM2*/RAM1*/RAM2*/RAM3*/RAM4*/IO* VMA*/RESET ;EN=/VUA

IF(VCC) /VUA   =  ENIN         ;ASSERTIVE HIGH VUA SIGNAL (INVERT EN FEEDBACK)

IF(VCC)  RESET =  S            ;SET
               + /R * RESET    ;RESET
               + /AR* RESET    ;AUTO RESET


FUNCTION TABLE

A15 A14 A13 A12 A11 /S /R /AR /RESET PH2 VMA /PROM1 /PROM2 /RAM1 /RAM2 /RAM3
/RAM4 /IO EN ENIN VUA

;ADDR1  S-R      /RE           PROM  --RAM--       ENABLE
;54321 /S /R /AR SET  PH2 VMA  1  2  1 2 3 4  I/O  OUT IN VUA   COMMENT
-------------------------------------------------------------------------------
 HHHHX  L  H  L   L    L   H   H  H  H H H H   H    H  H   L    RESET (/S=L)
 HHHHX  H  L  H   L    L   H   H  H  H H H H   H    H  H   L    AUTO-RESET
 HHHHX  H  L  L   H    L   H   H  H  H H H H   H    L  L   H    NO SELECT PH2=L
 HHHHX  H  L  L   H    H   L   H  H  H H H H   H    H  H   L    NO SELECT VMA=L
 HHHHX  H  L  L   H    H   H   L  H  H H H H   H    H  H   L    SELECT PROM1
 HHHLX  H  L  L   H    H   H   H  L  H H H H   H    H  H   L    SELECT PROM2
 LLLLL  H  L  L   H    H   H   H  H  L H H H   H    H  H   L    SELECT RAM1
 LLLLH  H  L  L   H    H   H   H  H  H L H H   H    H  H   L    SELECT RAM2
 LLLHL  H  L  L   H    H   H   H  H  H H L H   H    H  H   L    SELECT RAM3
 LLLHH  H  L  L   H    H   H   H  H  H H H L   H    H  H   L    SELECT RAM4
 HHLHH  H  L  L   H    H   H   H  H  H H H H   L    H  H   L    SELECT I/O PORT
-------------------------------------------------------------------------------


DESCRIPTION

THIS PAL20L10 INTERFACES BETWEEN THE MOTOROLA MC6800 MICROPROCESSOR AND ITS
SYSTEM COMPONENTS ON A SINGLE BOARD COMPUTER.  THE FUNCTIONS IT PERFORMS,
PREVIOUSLY DONE WITH RANDOM LOGIC ARE:  ADDRESS DECODING, MEMORY AND I/O
SELECT, RESET SIGNAL GENERATION, AND CONTROL OF THE BUFFER WHICH INTERFACES
THE DATA BUS TO OTHER BOARDS IN THE SYSTEM.