7800 Software Guide - Revision history

MSaarna at 14:21, 13 April 2025

2025-04-13T14:21:33Z

2023-08-19T17:15:37Z

2022-02-24T17:51:04Z

‎APPENDIX 1: 7800 MEMORY MAP

2022-02-24T17:49:51Z

‎APPENDIX 1: 7800 MEMORY MAP

2022-02-24T17:38:21Z

‎APPENDIX 1: 7800 MEMORY MAP

2021-03-10T21:21:35Z

2021-03-10T21:20:37Z

2020-10-01T00:20:37Z

updated signature (“encryption”) area boundaries to match Game Standards and Procedures and Bruce Tomlin’s signature generator

2020-04-25T03:47:21Z

fixed Fire 0 to Fire 1 for INPT4B, INPT4R

2020-04-25T03:42:00Z

fixed P2 to P1 for INPT3

@@ Line 646: / Line 646: @@
   | $281 || CTLSWA || Port A DDR, 0=input, 1=output
   |- style="vertical-align:top;"
-  | $282 || SWCHB || Port B, console switches (read only)
+  | $282 || SWCHB || Port B, console switches
   |- style="vertical-align:top;"
-  | $283 || CTLSWB || Port B DDR (hardwired as input)
+  | $283 || CTLSWB || Port B DDR
   |}

@@ Line 858: / Line 858: @@
   |}
-If holey DMA is enabled and graphics reads would reside in a DMA hole, no DMA penalty is incurred.
+If holey DMA is enabled and graphics reads would reside in a DMA hole, only 3 cycles of penalty for the graphic read is incurred, whatever the sprite width is.
 The end of VBLANK is made up of a DMA startup plus a Long shutdown.

@@ Line 741: / Line 741: @@
   | 3000 to FF7F || Available for mapping by external devices
   |- style="vertical-align:top;"
-  | FF80 to FFF7 || Reserved for Encryption
+  | FF80 to FFF7 || Reserved for cart encryption signature
   |- style="vertical-align:top;"
   | FFF8 to FFFF || Reserved for startup flags and 6502 vectors

@@ Line 737: / Line 737: @@
   | 2200 to 27FF || RAM
   |- style="vertical-align:top;"
-  | 2800 to 2FFF || Unavailable to cart. BIOS access to Fxxx appears as 2xxx access to the cart.
+  | 2800 to 2FFF || Unavailable for mapping by external devices. (BIOS conflict)
   |- style="vertical-align:top;"
   | 3000 to FF7F || Available for mapping by external devices

@@ Line 737: / Line 737: @@
   | 2200 to 27FF || RAM
   |- style="vertical-align:top;"
-  | 2800 to 2FFF || Same as 2000-27FF
+  | 2800 to 2FFF || Unavailable to cart. BIOS access to Fxxx appears as 2xxx access to the cart.
   |- style="vertical-align:top;"
   | 3000 to FF7F || Available for mapping by external devices

@@ Line 246: / Line 246: @@
 The CTRL register is arranged as follows:
-{| class="wikitable" style="table-layout: fixed; width: 80%; max-width: 640px;"
+{| class="wikitable" style="table-layout: fixed; width: 90%; max-width: 640px;"
   |+'''Color Register Layout'''
   |- style="vertical-align:top;"

@@ Line 254: / Line 254: @@
   | colspan="2" | DMA Control: 0,1=TEST DO NOT USE, as it could break the console. 2=normal DMA. 3=no DMA
   | Character Width: 0=single byte characters, 1=double byte characters
-  | Border Control: 0=BACKGRND colored screen border, 1=black screen border
+  | Border Control: 0=black screen border, 1=BACKGRND color border
   | Kangaroo Mode: 0=regular transparency, 1=kangaroo mode with no transparency
   | colspan="2" | Read Mode: 0=160A/160B 1=N/A 2=320B/320D 3=320A/320C

@@ Line 760: / Line 760: @@
 ; ** some common alternate names for INPT0/1/2/3
-INPT4B   = $08     ;Joystick 0 Fire 1                            read-only
+INPT4B   = $08     ;Joystick 0 Fire 0                            read-only
 INPT4A   = $09     ;Joystick 0 Fire 1                            read-only
 INPT5B   = $0A     ;Joystick 1 Fire 0                            read-only
 INPT5A   = $0B     ;Joystick 1 Fire 1                            read-only
-INPT4R   = $08     ;Joystick 0 Fire 1                            read-only
+INPT4R   = $08     ;Joystick 0 Fire 0                            read-only
 INPT4L   = $09     ;Joystick 0 Fire 1                            read-only
 INPT5R   = $0A     ;Joystick 1 Fire 0                            read-only

@@ Line 593: / Line 593: @@
   | INPT2 || P1, right button || Bit 7=1 if the button is pushed
   |- style="vertical-align:top;"
-  | INPT3 || P2, left button || Bit 7=1 if the button is pushed
+  | INPT3 || P1, left button || Bit 7=1 if the button is pushed
   |}