PLE8P8                                              PLE DESIGN SPECIFICATION
P5001                                                 ULRIK MUELLER 04/01/83
MEMORY ADDRESS DECODER
MMI SANTA CLARA, CALIFORNIA
.ADD A11 A12 A13 A14 A15 /MREQ
.DAT /CE1 /CE2 /CE3 /CE4 /CE5 /CE6 /CE7 /CE8


CE1 = /A11*/A12*/A13*/A14*/A15* MREQ      ; SELECTS ADDRESS RANGE 0K-2K

CE2 =  A11*/A12*/A13*/A14*/A15* MREQ      ; SELECTS ADDRESS RANGE 2K-4K

CE3 = /A11* A12*/A13*/A14*/A15* MREQ      ; SELECTS ADDRESS RANGE 4K-6K 

CE4 =  A11* A12*/A13*/A14*/A15* MREQ      ; SELECTS ADDRESS RANGE 6K-8K

CE5 = /A11*/A12* A13*/A14*/A15* MREQ      ; SELECTS ADDRESS RANGE 8K-10K 

CE6 =  A11*/A12* A13*/A14*/A15* MREQ      ; SELECTS ADDRESS RANGE 10K-12K 

CE7 = /A11* A12* A13*/A14*/A15* MREQ      ; SELECTS ADDRESS RANGE 12K-14K

CE8 =  A11* A12* A13*/A14*/A15* MREQ      ; SELECTS ADDRESS RANGE 14K-16K


FUNCTION TABLE

A11 A12 A13 A14 A15 /MREQ /CE1 /CE2 /CE3 /CE4 /CE5 /CE6 /CE7 /CE8

; ADD LINES
;   11111               CHIP ENABLES
;   12345      /MREQ      12345678        COMMENTS
-----------------------------------------------------------------------
    LLLLL        L        LHHHHHHH        SELECT ADDRESS RANGE 0-2K
    HLLLL        L        HLHHHHHH        SELECT ADDRESS RANGE 2K-4K
    LHLLL        L        HHLHHHHH        SELECT ADDRESS RANGE 4K-6K
    HHLLL        L        HHHLHHHH        SELECT ADDRESS RANGE 6K-8K
    LLHLL        L        HHHHLHHH        SELECT ADDRESS RANGE 8K-10K
    HLHLL        L        HHHHHLHH        SELECT ADDRESS RANGE 10K-12K
    LHHLL        L        HHHHHHLH        SELECT ADDRESS RANGE 12K-14K
    HHHLL        L        HHHHHHHL        SELECT ADDRESS RANGE 14K-16K
    XXXXX        H        HHHHHHHH        NO MEMORY SELECT (/MREQ=H)
-----------------------------------------------------------------------


DESCRIPTION

THIS PLE8P8 PROVIDES A SINGLE CHIP ADDRESS DECODER FOR USE WITH MANY POPULAR
8-BIT MICROPROCESSORS SUCH AS THE Z80 AND 8080.  THE FIVE MSB ADDRESS LINES
(A11-A15) AND THE MEMORY REQUEST LINE (/MREQ) FROM THE Z80 MICROPROCESSOR ARE
DECODED TO PRODUCE EIGHT ACTIVE LOW CHIP ENABLES (/CE1-/CE8) TO SELECT A RANGE
OF 2K BYTES FROM A BANK OF EIGHT 2Kx8 STATIC RAMS.  THIS BANK OF STATIC RAMS
WILL OCCUPY THE LOWEST 16K BYTES OF ADDRESS SPACE LEAVING THE UPPER 48K BYTE
SPACE AVAILABLE FOR OTHER MEMORIES AND I/O.  THE PLE8P8 HAS THREE ADDITIONAL
INPUTS WHICH CAN BE RESERVED FOR FUTURE SYSTEM EXPANSION.