BBC_ULA1.pld

GAL16V8
BBC_ULA1
; DISEN = Display Enable (active high)
; CURSOR = 6845 CURSOR signal
; FIN = Flash INhibit bit from control register
; F = flash bit from palette (highest bit)
; BIN/GIN/RIN = RGB signal from SAA5050 Teletext (MODE 7)
; ROUT/GOUT/BOUT = switched RGB output
; TMODE = Teletext mode input pin from control register
; HBIN/HGIN/HRIN = RGB input from palette (all other modes)
;

DISEN NC NC CURSOR FIN F BIN GIN RIN   GND
  TMODE  NC ROUT GOUT BOUT  HBIN HGIN HRIN NC VCC

HBIN.T = GND
HGIN.T = GND
HRIN.T = GND

HBIN.E = GND
HGIN.E = GND
HRIN.E = GND

ROUT =   RIN  * TMODE
       + /HRIN *  F * /FIN * /TMODE * DISEN
       +  HRIN *  F *  FIN * /TMODE * DISEN
       + /HRIN * /F * /TMODE * DISEN
       + CURSOR * DISEN

GOUT =   GIN  * TMODE
       + /HGIN *  F * /FIN * /TMODE * DISEN
       +  HGIN *  F *  FIN * /TMODE * DISEN
       + /HGIN * /F * /TMODE * DISEN
       + CURSOR * DISEN

BOUT =   BIN  * TMODE
       + /HBIN *  F * /FIN * /TMODE * DISEN
       +  HBIN *  F *  FIN * /TMODE * DISEN
       + /HBIN * /F * /TMODE * DISEN
       + CURSOR * DISEN