CoCo: add coco_crt target

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 * Preliminary support for Tandy Color Computer running RS-DOS.
 
+* Preliminary support for 16K cartridges for Tandy Color Computer.
+
 * Added support for modifying large variables via pointers.
 
 * Added the ability to declare structure alignment.

docs/api/coco-programming-guide.md

@@ -2,6 +2,8 @@
 
 ### A note about Color Computer
 
+#### `coco_rsdos` target
+
 The `coco_rsdos` target creates binary files that can run on Tandy Color Computer running RS-DOS.
 
 The compiler output is a raw machine code file with the `.bin` extension, which then has to be put on a disk. 
@@ -13,3 +15,12 @@ You can do it using `imgtool` from the [MAME project](https://www.mamedev.org/):
 The resulting file can then be loaded and ran using the following commands:
 
     LOADM"CO":EXEC
+
+#### `coco_crt` target
+
+The `coco_crt` target creates 16k cartridge images that can run on Tandy Color Computer or Dragon.
+
+The program is run directly from ROM;
+typical ROM programming guidelines apply, see [the ROM vs RAM guide](./rom-vs-ram.md).
+
+The `main` function is not allowed to return.

docs/api/target-platforms.md

@@ -102,6 +102,9 @@ The compiler emits COM files.
 * `coco_rsdos` – Tandy Color Computer running RS-DOS. (very experimental)
 Read [the Color Computer programming guide](./coco-programming-guide.md) for more info.
 
+* `coco_crt` – 16K cartridge for Tandy Color Computer. (very experimental)
+Read [the Color Computer programming guide](./coco-programming-guide.md) for more info.
+
 * `dos_com` – a COM file for DOS on IBM PC. (very experimental)
 
 * `x16_experimental` – Commander X16; very experimental,

include/coco/crt.mfk

@@ -0,0 +1,5 @@
+asm void __init() @$c000 {
+    JSR main
+    __init__infinite_loop:
+    BRA __init__infinite_loop
+}

include/platform/coco_crt.ini

@@ -0,0 +1,32 @@
+; a cartridge program for Tandy Color Computer/Dragon
+; VERY EXPERIMENTAL
+[compilation]
+arch=6809
+encoding=coco
+screen_encoding=cocoscr
+modules=default_panic,stdlib,coco/kernal,coco/crt
+u_stack=true
+
+[allocation]
+segments=default,prgrom
+ram_init_segment=prgrom
+default_code_segment=prgrom
+segment_prgrom_start=$c000
+segment_prgrom_end=$ffff
+segment_default_start=$3f00
+segment_default_end=$7fff
+
+[define]
+COCO=1
+WIDESCREEN=0
+KEYBOARD=1
+; TODO: ?
+JOYSTICKS=1
+HAS_BITMAP_MODE=1
+
+[output]
+style=single
+format=prgrom:$c000:$ffff
+extension=.rom
+
+