NES mapper experiments

include/nes_mmc4.ini

@@ -0,0 +1,64 @@
+; a NES MMC4 cartridge, uses iNES mapper 10
+; 8×16 kB PRGROM and 32×4kB CHRROM
+; $c000–$ffff is assumed to be fixed to prgrom7, $8000-$bfff can be switched
+; uses horizontal mirroring:
+; - to use vertical mirroring, change byte #6 of the header from $A0 to $A1
+; uses extra 8K of RAM at $6000–$7fff that is not battery-backed:
+; - to disable it, change byte #10 of the header from $07 to 0 and remove the ram segment
+; - to make it battery-backed, change byte #10 of the header from $07 to $77
+; output file size: 262160 bytes
+
+[compilation]
+arch=ricoh
+modules=nes_hardware,nes_routines,default_panic,nes_mmc4
+ro_arrays=true
+
+[allocation]
+zp_pointers=all
+
+segments=default,ram,prgrom0,prgrom1,prgrom2,prgrom3,prgrom4,prgrom5,prgrom6,prgrom7,chrrom0,chrrom1
+default_code_segment=prgrom7
+
+segment_default_start=$200
+segment_default_end=$7ff
+
+segment_ram_start=$6000
+segment_ram_end=$7fff
+
+segment_prgrom7_start=$c000
+segment_prgrom7_end=$ffff
+
+segment_prgrom0_start=$8000
+segment_prgrom0_end=$bfff
+
+segment_prgrom1_start=$8000
+segment_prgrom1_end=$bfff
+
+segment_prgrom2_start=$8000
+segment_prgrom2_end=$bfff
+
+segment_prgrom3_start=$8000
+segment_prgrom3_end=$bfff
+
+segment_prgrom4_start=$8000
+segment_prgrom4_end=$bfff
+
+segment_prgrom5_start=$8000
+segment_prgrom5_end=$bfff
+
+segment_prgrom6_start=$8000
+segment_prgrom6_end=$bfff
+
+segment_chrrom0_start=$0000
+segment_chrrom0_end=$ffff
+
+segment_chrrom1_start=$0000
+segment_chrrom1_end=$ffff
+
+[output]
+style=single
+format=$4E,$45,$53,$1A,   8,16,$A0,8, 0,0,$07,0, 2,0,0,0, prgrom0:$8000:$bfff,prgrom1:$8000:$bfff,prgrom2:$8000:$bfff,prgrom3:$8000:$bfff,prgrom4:$8000:$bfff,prgrom5:$8000:$bfff,prgrom6:$8000:$bfff,prgrom7:$c000:$ffff,chrrom0:$0000:$ffff,chrrom1:$0000:$ffff
+
+extension=nes
+
+

include/nes_mmc4.mfk

@@ -0,0 +1,32 @@
+asm inline void set_prg_bank(byte a) {
+    STA $A000
+    ? RTS
+}
+
+// calling with with e.g. $1E will set $0000-$0fff to $E000-$EFFF in chrrom1
+asm inline void set_chr_bank0(byte a) {
+    STA $B000
+    STA $C000
+    ? RTS
+}
+
+// calling with with e.g. $1E will set $1000-$1fff to $E000-$EFFF in chrrom1
+asm inline void set_chr_bank1(byte a) {
+    STA $D000
+    STA $E000
+    ? RTS
+}
+
+// TODO: FD/FE latches
+
+asm inline void set_vertical_mirroring() {
+    LDA #0
+    STA $F000
+    ? RTS
+}
+asm inline void set_horizontal_mirroring() {
+    LDA #1
+    STA $F000
+    ? RTS
+}
+

include/nes_small.ini

@@ -1,7 +1,8 @@
 ; a very simple NES cartridge format
 ; uses mapper 0 and no bankswitching, so it's only good for very simple games
-; assumes CHRROM is at chrrom:$0000-$3fff and PRGROM is at prgrom:$8000-$ffff
+; assumes CHRROM is at chrrom:$0000-$1fff and PRGROM is at prgrom:$8000-$ffff
 ; uses horizontal mirroring; to use vertical mirroring, change byte #6 of the header from 0 to 1
+; output file size: 40976 bytes
 
 [compilation]
 arch=ricoh
@@ -21,11 +22,11 @@ segment_prgrom_start=$8000
 segment_prgrom_end=$ffff
 
 segment_chrrom_start=$0000
-segment_chrrom_end=$3fff
+segment_chrrom_end=$1fff
 
 [output]
 style=single
-format=$4E,$45,$53,$1A,   2,2,0,0, 0,0,0,0, 0,0,0,0, prgrom:$8000:$ffff, chrrom:$0000:$3fff
+format=$4E,$45,$53,$1A,   2,1,0,0, 0,0,0,0, 0,0,0,0, prgrom:$8000:$ffff, chrrom:$0000:$1fff
 extension=nes