A2000 Pal Equations - Commodore Amiga A500 Technical Reference Manual

A2000 PAL Equations

PAL20L8'
PART NO.: 380 XXX-01 DESCRPT.:PALEN
MEM- AND DTACK-DECODER FOR A2500 MAINBOARD (U26) ASSY 380...
COMMODORE BSW
A23 A22 A21 A20 A19 A18 PRW AS DBR OVL OVR GND
C1 C3 VPA MYRAME CLKE RGAE RE DTACK BLS ROME XRDY VCC
IF (OVR) /VPA = /AS*A23*/A22*A21
/MYRAME = /AS*DTACK*A23*A22*A21*OVR*/C1*C3
+ /AS*DTACK*/A23*/A22*/A21*OVR*OVL*/C1*C3
/AS*DTACK*A23*A22/A21*A20*A19*/A18*OVR*/C1*C3
+ /MYRAME*/C1
+ /MYRAME*/C3
/RE = DBR*/AS*DTACK*/A23*/A22«/A21*OVRVOVL*
/C1*C3
+ /RE*/C1
+ /RE*/C3
IF (OVR) /DTACK =
/AS*/A23"/A22*A21*XRDY
+ /AS*/A23*A22*XRDY
+ /AS*A23*/A22*/A21*XRDY
+ /MYRAME*XRDY*/C3
+ /RE*/C3
+ /RGAE*/C3
+ /DTACK*/AS*XRDY
/RGAE = DBR*/AS*DTACK*A23*A22*/A21*A20*/A19*
+ DBR*/AS*DTACK*A23*A22*/A21*A20*A19*A18*OVR*/C1*C3;$DC0000-$DFFFFF
+ DBR*/AS*DTACK*A23*A22*/A21*/A20*
+ /RGAE*/C1
+ /RGAE*/C3
/BLS = /AS*DTACK*/A23*/A22*/A21*OVR*/OVL*/C1*C3
+ /AS*DTACK*A23*A22*/A21*OVR*/C1*C3
+ /BLS*/C1
+ /BLS*/C3
REV.2
! ! PRELIMENARY ! !
229
PAL DESIGN SPECIFICATION
FRANK ULLMANN 03-09-86
; PERIPHERAL ACCESS
; $A00000-BFFFFF
; $E00000-FFFFFF
; $000000-1FFFFF IF
; OVL=H, OVR=H !
; $D80000-DBFFFF
; $000000-1FFFFF IF
; OVL=L, OVR=H !
; $200000-3FFFFF EXP RAM
; $400000-7FFFFF "
; $800000-9FFFFF "
; $000000-1FFFFF OVL=H
; AND SE00000-FFFFFF
; $000000-1FFFFF OVL=L
; $C00000-D7FFFF
; AND $DC0000-DF0000
OVR*/C1*C3;$D00000-$D7FFFF
OVR*/C1*C3;$C00000-$CFFFFF
; $000000-1 FFFFF OVL=L
; $C00000-DFFFFF
Section 7.3
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