A5200: Adds an Atari 5200 section to the manual.

Author: dmsc

README.md

@@ -27,6 +27,7 @@ There is a full manual with all the supported syntax in the file [manual.md](man
 
 To use the cross-compiler, download from the releases and see [compiler/USAGE.md](compiler/USAGE.md) for instructions.
 
+For the Atari 5200 support, read the [a5200.md](Atari 5200 manual appendix).
 
 Sample files
 ------------

a5200.md

@@ -0,0 +1,83 @@
+Atari 5200 console support
+==========================
+
+*Note: This is an appendix to the main FastBasic manual.*
+
+The FastBasic cross compiler supports the Atari 5200 console as a target,
+allowing to port programs from the Atari 8-bit computers with minor
+modifications.
+
+
+RAM Usage
+---------
+
+The Atari 5200 console has only 16kb of RAM, this means that you have to
+minimize RAM usage in your program.
+
+For compatibility with most programs, `DLI` and `DATA` statements are stored in
+RAM, this means that you should put big `DATA` statements in ROM by using the
+construct:
+
+    DATA mydata() BYTE ROM = 1, 2, 3, ....
+    DATA font() BYTEFILE ROM "myfont.fnt"
+
+Note that DATA in ROM can't be modified at runtime, so you must select the type
+appropriately.
+
+
+Operating System support
+------------------------
+
+The Atari 5200 console lacks the OS ROM of the Atari 8-bit computers, so all
+the functionality that depends on the OS must be reimplemented.
+
+Currently, the target lacks:
+
+- Floating point support: only integer operations are supported.
+- Graphics modes: the included runtime only implements graphic modes 0, 1, 2, 7
+  to 13 and 15.
+- Text window: the graphic modes with a text window are not implemented.
+- Filled lines: only PLOT and DRAWTO are implemented, there is no `FILLTO`
+  command.
+- Input/Output: Only the screen output an keypad input are supported, there is
+  no I/O channels, `OPEN` or `XIO`.
+
+
+Hardware Registers
+------------------
+
+The Atari 5200 changes the location of hardware registers for POKEY (from $D200
+to $D800) and GTIA (from $D000 to $C000), so direct `POKE`s to memory must be
+changed.
+
+Also, `DLI` support also needs to change the address of color and P/M registers,
+you can use this table for useful registers:
+
+|Address| Register                  |
+| ----- | ------------------------- |
+| $C000 | Player 0 horizontal pos.  |
+| $C001 | Player 1 horizontal pos.  |
+| $C002 | Player 2 horizontal pos.  |
+| $C003 | Player 3 horizontal pos.  |
+| $C004 | Missile 0 horizontal pos. |
+| $C005 | Missile 0 horizontal pos. |
+| $C006 | Missile 0 horizontal pos. |
+| $C007 | Missile 0 horizontal pos. |
+| $C012 | Color of Player 0         |
+| $C013 | Color of Player 0         |
+| $C014 | Color of Player 0         |
+| $C015 | Color of Player 0         |
+| $C016 | Color register 0          |
+| $C017 | Color register 1          |
+| $C018 | Color register 2          |
+| $C019 | Color register 3          |
+| $C01A | Color of Background       |
+
+Also remember that the Atari 5200 does not have a PIA, console keys and
+keyboard, all controllers are analog and have a keypad.
+
+FastBasic emulates the standard 8-bit joystick, so the `STICK()` and `STRIG()`
+functions return the same values.
+
+
+

rules.mak

@@ -246,8 +246,8 @@ $(LIB_A5200): $(A5200_OBJS) | build/compiler $(AR65_HOST)
 	$(Q)$(AR65_HOST) a $@ $^
 
 # Copy manual to compiler changing the version string.
-build/compiler/MANUAL.md: manual.md version.mk | build/compiler
-	$(Q)LC_ALL=C sed 's/%VERSION%/$(VERSION)/' < $< > $@
+build/compiler/MANUAL.md: manual.md a5200.md | version.mk build/compiler
+	$(Q)LC_ALL=C sed 's/%VERSION%/$(VERSION)/' $(filter %.md,$^) > $@
 
 # Copy other files to compiler folder
 build/compiler/%: compiler/% | build/compiler