Revision as of 08:15, 19 February 2017

68k vector table swapping

The 68k vector table is swapped with the System ROM one by using REG_SWPBIOS or REG_SWPROM.

A22I~A23I are used to make the address appear to address decoding chips as a system ROM access instead of a P ROM access.

User:Kyuusaku: {A23Z,A22Z} = A[23:22] ^ 2{~|{A[21:7],^A[23:22],VEC}}

55 = sPCK1B 56 = sPCK2B

Acts just as a buffer.

OpenOffice Draw file: File:Neo-e0.odg

@@ Line 8: / Line 8: @@
 }}
-=[[System ROM]] vector table swapping=
+=68k vector table swapping=
-When 68k A8~A23 = 0 and the [[System ROM]]'s vector table is chosen (by using {{Reg|REG_SWPBIOS}} or {{Reg|REG_SWPROM}}), A22I~A23I outputs are set to 1.  This makes the address appear to address decoding chips as a system ROM access instead of a [[P ROM]] access.
+The 68k vector table is swapped with the [[System ROM]] one by using {{Reg|REG_SWPBIOS}} or {{Reg|REG_SWPROM}}.
+A22I~A23I are used to make the address appear to address decoding chips as a system ROM access instead of a [[P ROM]] access.
+{|class="wikitable"
+!rowspan=2|Address||colspan=2|Maps to
+|-
+!VEC = 0||VEC = 1
+|-
+|$000000~$0000FF||$C00000~$C000FF||$000000~$0000FF
+|-
+|$000100~$BFFFFF||colspan=2|$000100~$BFFFFF
+|-
+|$C00000~$C000FF||$000000~$0000FF||$C00000~$C000FF
+|-
+|$C00100~$FFFFFF||colspan=2|$C00100~$FFFFFF
+|}
 [[User:Kyuusaku]]: {A23Z,A22Z} = A[23:22] ^ 2{~|{A[21:7],^A[23:22],VEC}}
-On the AES, the AND gate is used to get /SROMOE from /SROMOEL AND /SROMOEU.
 =Pinouts=