Title       Stack latch PAL
Pattern     latch.pds
Revision    1.0
Author      Bret Victor
Company     lloyd
Date        May 11, 1999

Chip        U1         PAL20V8


; why use a 20V8 instead of a 373/374?  Because I've got
; a ton of 20V8's lying around.

; pins

pin   1      CLK          ;input    clock (actually, also /BoardSelect)
pin   2      SEL          ;input    /BoardSelect from hc11
pin   3      RNOTW        ;input    read/notWrite bit from hc11
pin   4      D0           ;input    data line from hc11
pin   5      D1           ;input    data line from hc11
pin   6      D2           ;input    data line from hc11
pin   7      D3           ;input    data line from hc11
pin   8      D4           ;input    data line from hc11
pin   9      D5           ;input    data line from hc11
pin   10     D6           ;input    data line from hc11
pin   11     D7           ;input    data line from hc11
pin   12     GND          ;supply   GND

pin   13     OE           ;input    registered /OE, tied low externally
pin   14     nc14         ;input    unused  
pin   15     LATCH0  reg  ;output   latch output
pin   16     LATCH1  reg  ;output   latch output
pin   17     LATCH2  reg  ;output   latch output
pin   18     LATCH3  reg  ;output   latch output
pin   19     LATCH4  reg  ;output   latch output
pin   20     LATCH5  reg  ;output   latch output
pin   21     LATCH6  reg  ;output   latch output
pin   22     LATCH7  reg  ;output   latch output
pin   23     nc23         ;input    unused
pin   24     VCC          ;supply   VCC

EQUATIONS

LATCH0 := (D0 * /RNOTW) + (LATCH0 * RNOTW)
LATCH1 := (D1 * /RNOTW) + (LATCH1 * RNOTW)
LATCH2 := (D2 * /RNOTW) + (LATCH2 * RNOTW)
LATCH3 := (D3 * /RNOTW) + (LATCH3 * RNOTW)
LATCH4 := (D4 * /RNOTW) + (LATCH4 * RNOTW)
LATCH5 := (D5 * /RNOTW) + (LATCH5 * RNOTW)
LATCH6 := (D6 * /RNOTW) + (LATCH6 * RNOTW)
LATCH7 := (D7 * /RNOTW) + (LATCH7 * RNOTW)