Differences

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--- base:memory_management [2019-04-10 03:12] – changed start of ram from 0000 to 0002 white_flame
+++ base:memory_management [2022-03-05 11:12] – finally got around to the "with cartridges" section white_flame
@@ Line 30: / Line 30: @@
 |$37 +55 %111 |BASIC |I/O |KERNAL|Default|
-The cartridge port also has the GAME and EXROM pins, which meddle with the memory map even further.  See the Programmer's Reference Guide for that.
+====== With Cartridges ======
+The expansion port has 2 configuration inputs (/EXROM and /GAME), and 4 chip select outputs (/IO1, /IO2, /ROML, /ROMH).
+/IO1 and /IO2 lines are active on both reads & writes, any time that I/O is banked in:
+  * /IO1 = $DE00 - $DEFF
+  * /IO2 = $DF00 - $DFFF
+/ROML and /ROMH are active on reads depending on how the cartridge sets the configuration inputs.  Normally, ROML sits right before the BASIC ROM at $8000-9FFF, while ROMH replaces BASIC itself.  Writes to these areas still go to internal RAM and do not acivate the external chip select lines.  Ultimax mode has ROMH replacing the KERNAL and unmaps a lot of the internal RAM.
+===== Cart pulls /EXROM low =====
+The simplest cartridge configuration, only using ROML.  Any time the BASIC ROM is visible in at $A000, ROML is also visible in the 8kB before it.
+^$01 value ^$8000-9FFF ^$A000-BFFF ^$D000-DFFF ^$E000-FFFF ^Notes^
+|$30 +48 %000 |RAM |RAM |RAM |RAM|
+|$31 +49 %001 |RAM |RAM |CHARROM |RAM|
+|$32 +50 %010 |RAM |RAM |CHARROM |KERNAL|
+|$33 +51 %011 |**__ROML__** |BASIC |CHARROM |KERNAL|
+|
+|$34 +52 %100 |RAM |RAM |RAM |RAM|
+|$35 +53 %101 |RAM |RAM |I/O |RAM|
+|$36 +54 %110 |RAM |RAM |I/O |KERNAL|
+|$37 +55 %111 |**__ROML__** |BASIC |I/O |KERNAL|Default|
+===== Cart pulls /EXROM + /GAME low =====
+ROML is before BASIC, and is swapped out with the LORAM bit in $01; while ROMH replaces BASIC and is swapped out alongside the KERNAL with HIRAM.  There is no KERNAL-only mode in this configuration.
+^$01 value ^$8000-9FFF ^$A000-BFFF ^$D000-DFFF ^$E000-FFFF ^Notes^
+|$30 +48 %000 |RAM |RAM |RAM |RAM|
+|$31 +49 %001 |RAM |RAM |CHARROM |RAM|
+|$32 +50 %010 |RAM |**__ROMH__** |CHARROM |KERNAL|
+|$33 +51 %011 |**__ROML__** |**__ROMH__** |CHARROM |KERNAL|
+|
+|$34 +52 %100 |RAM |RAM |RAM |RAM|
+|$35 +53 %101 |RAM |RAM |I/O |RAM|
+|$36 +54 %110 |RAM |**__ROMH__** |I/O |KERNAL|
+|$37 +55 %111 |**__ROML__** |**__ROMH__** |I/O |KERNAL|Default|
+===== Cart pulls only /GAME low (Ultimax mode) =====
+ROMH replaces the KERNAL at $E000, ROML is still at $8000.  Only the lowest 4kB of internal RAM remains visible, and I/O cannot be swapped out.  None of the bits in $01 affect the banking in this mode.
+^$0000-0FFF ^$1000-7FFF ^$8000-9FFF ^$A000-CFFF ^$D000-DFFF ^$E000-FFFF ^
+|RAM |unmapped |**__ROML__** |unmapped |I/O |**__ROMH__**|
 - White Flame