Preliminary Atari 2600 support

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## Current version
 
-* Preliminary BBC Micro support.
+* Preliminary Atari 2600 and BBC Micro support.
 
 * Added array initialization syntax with `for` (not yet finalized).
 

README.md

@@ -28,6 +28,8 @@ For binary releases, see: https://github.com/KarolS/millfork/releases (latest: 0
     
     * Famicom/NES (the second most important target)
     
+    * Atari 2600 (experimental)
+    
     * Atari 8-bit computers
     
     * BBC Micro

docs/api/target-platforms.md

@@ -35,6 +35,8 @@ The following platforms are currently supported:
 For more complex programs, you need to create your own "platform" definition.  
 Read [the NES programming guide](./famicom-programming-guide.md) for more info.
 
+* `vcs` – Atari VCS (also known as Atari 2600), 4K cartridge (experimental)
+
 * `a8` – Atari 8-bit computers
 
 * `bbcmicro` – BBC Micro model B (32k RAM)

examples/README.md

@@ -33,3 +33,7 @@
 ## Apple II examples
 
 * [Bell](apple2/bell.mfk) – a program that goes \*ding!\*
+
+## Atari 2600 examples
+
+* [Colors](vcs/colors.mfk) – simple static rasterbars

examples/vcs/colors.mfk

@@ -0,0 +1,11 @@
+void main() {
+    byte y
+    while true {
+        start_frame()
+        for y,0,until,192 {
+            COLUBK = y
+            wsync()
+        }
+        end_frame()
+    }
+}

include/vcs.ini

@@ -0,0 +1,29 @@
+; an Atari VCS cartridge format without any bankswitching
+; output file size: 4096 bytes
+
+[compilation]
+arch=nmos
+modules=vcs_hardware,default_panic
+ro_arrays=true
+; use -fzp-register to override this:
+zeropage_register=false
+
+
+[allocation]
+zp_pointers=$80,$82,$84,$86,$88,$8a,$8c,$8e,$90,$92,$94,$96,$98,$9a,$9c,$9e,$a0,$a2,$a4
+segments=default,prgrom
+default_code_segment=prgrom
+
+; last 16 bytes are left for stack
+segment_default_start=$80
+segment_default_end=$ef
+
+segment_prgrom_start=$f000
+segment_prgrom_end=$ffff
+
+[output]
+style=single
+format=prgrom:$f000:$ffff
+extension=bin
+
+

include/vcs_hardware.mfk

@@ -0,0 +1,112 @@
+byte VSYNC @$00
+byte VBLANK @$01
+byte WSYNC @$02
+byte RSYNC @$03
+byte NUSIZ0 @$04
+byte NUSIZ1 @$05
+byte COLUP0 @$06
+byte COLUP1 @$07
+byte COLUPF @$08
+byte COLUBK @$09
+byte CTRLPF @$0A
+byte REFP0 @$0B
+byte REFP1 @$0C
+byte PF0 @$0D
+byte PF1 @$0E
+byte PF2 @$0F
+byte RESP0 @$10
+byte RESP1 @$11
+byte RESM0 @$12
+byte RESM1 @$13
+byte RESBL @$14
+byte AUDC0 @$15
+byte AUDC1 @$16
+byte AUDF0 @$17
+byte AUDF1 @$18
+byte AUDV0 @$19
+byte AUDV1 @$1A
+byte GRP0 @$1B
+byte GRP1 @$1C
+byte ENAM0 @$1D
+byte ENAM1 @$1E
+byte ENABL @$1F
+byte HMP0 @$20
+byte HMP1 @$21
+byte HMM0 @$22
+byte HMM1 @$23
+byte HMBL @$24
+byte VDELP0 @$25
+byte VDELP1 @$26
+byte VDELBL @$27
+byte RESMP0 @$28
+byte RESMP1 @$29
+byte HMOVE @$2A
+byte HMCLR @$2B
+byte CXCLR @$2C
+byte CXM0P @$30
+byte CXM1P @$31
+byte CXP0FB @$32
+byte CXP1FB @$33
+byte CXM0FB @$34
+byte CXM1FB @$35
+byte CXBLPF @$36
+byte CXPPMM @$37
+byte INPT0 @$38
+byte INPT1 @$39
+byte INPT2 @$3A
+byte INPT3 @$3B
+byte INPT4 @$3C
+byte INPT5 @$3D
+byte SWCHA @$0280
+byte SWACNT @$0281
+byte SWCHB @$0282
+byte SWBCNT @$0283
+byte INTIM @$0284
+byte INSTAT @$0285
+byte TIM1T @$0294
+byte TIM8T @$0295
+byte TIM64T @$0296
+byte T1024T @$0297
+
+
+macro asm void wsync() {
+    STA WSYNC
+}
+
+macro asm void start_frame() {
+    LDA #0
+    STA VBLANK
+    LDA #2
+    STA VSYNC
+    STA WSYNC
+    STA WSYNC
+    STA WSYNC
+    LDA #0
+    STA VSYNC
+    LDX #37
+    start_frame_loop:
+    STA WSYNC
+    DEX
+    BNE start_frame_loop
+}
+macro asm void end_frame() {
+    LDA #%01000010
+    STA VBLANK
+    LDX #30
+    end_frame_loop:
+    STA WSYNC
+    DEX
+    BNE end_frame_loop
+}
+
+asm void reset_routine() @$FFF4 {
+    LDX #$FF
+    TXS
+    JMP main
+}
+
+array __vectors @$FFFA = [
+    reset_routine.addr.lo, reset_routine.addr.hi,
+    reset_routine.addr.lo, reset_routine.addr.hi,
+    reset_routine.addr.lo, reset_routine.addr.hi
+]

include/vcs_secam_palette.mfk

@@ -0,0 +1,9 @@
+const byte black = 0
+const byte blue = $d2
+const byte red = $64
+const byte purple = $86
+const byte green = $38
+const byte cyan = $9a
+const byte yellow = $2c
+const byte white = $0e
+