Fixed code size overflow crash

Adding the new keyboard code in the last release pushed the code
size beyond the 4K region allocated for it. The colour/mono
functions were then corrupted by the stack or overwritten by the
look-up tables generated at B000.

The look-up tables have been moved to B200, to give an extra 512
bytes of space. The stack has also been moved to hang back from
C000, which is after the end of the look-up tables.

Also changed the green ghost to dark yellow, to be closer to its
original orange colour. Changing the maze colour also uses the
bright version unless Shift is pressed.

.gitignore

@@ -5,3 +5,4 @@ pacemuzx.tap
 pacemuzx.sym
 pacemuzx.o
 pacman.6?
+/Thumbs.db

ReadMe.txt

@@ -1,7 +1,7 @@
-Pac-Man Emulator for Sinclair Spectrum (v1.4)
+Pac-Man Emulator for Sinclair Spectrum (v1.5)
 ---------------------------------------------
 
-This program requires a Spectrum +2A/+3, and will not work on earlier models.
+This program requires a Spectrum +2A/+2B/+3, and won't work on earlier models.
 
 The Pac-Man ROMs cannot be supplied with this program, so you must supply your
 own copies of the following files (from the Midway ROM set):
@@ -14,12 +14,33 @@ or combine manually using:
 
   cat start.part pacman.6[efhj] end.part > pacemuzx.tap
 
+Then load the .tap tape image in a Spectrum emulator of your choosing.
+
+Controls:
+
+  1 = 1 player start
+  2 = 2 player start
+  3 = insert coin
+
+  C = colour sprites
+  M = mono sprites
+  H = hard difficulty (hold during ROM boot)
+
+  Cursor keys, Q/A/O/P, Kempston/Sinclair joysticks = joystick control
+
+  Sym-1 to Sym-7 = set display colour, add Shift for bright
+
 Many thanks to #zx and WOS for feedback and testing :)
 
 Enjoy!
 
 ---
 
+Version 1.5 (2016/11/19)
+- Fixed code overflow crash on mono/colour toggle (thanks Matthew Logue)
+- Changed maze colours to be bright by default, with Shift to dim
+- Changed green ghost to non-bright yellow, to be closer to orange original
+
 Version 1.4 (2014/03/01)
 - Added support for diagonal control inputs from keyboard and 8-way joysticks
 

pacemuzx.asm

@@ -1,4 +1,4 @@
-; Pac-Man hardware emulation for the Sinclair ZX Spectrum (v1.4)
+; Pac-Man hardware emulation for the Sinclair ZX Spectrum (v1.5)
 ;
 ; http://simonowen.com/spectrum/pacemuzx/
 
@@ -17,8 +17,8 @@ colour:        equ 1                ; non-zero for switchable colour/mono, zero
 ; 4000-50ff - Pac-Man display, I/O and working RAM
 ; 5100-7fff - unused
 ; 8000-9fff - 2nd half of sprite data
-; a000-afff - emulation code
-; b000-bfff - look-up tables
+; a000-b1ff - emulation code
+; b200-bfff - look-up tables
 ; c000-dfff - 8K sound table
 ; e000-ffff - first 8K of Pac-Man ROM (unpatched)
 ;
@@ -27,8 +27,8 @@ colour:        equ 1                ; non-zero for switchable colour/mono, zero
 ; 4000-5aff - Spectrum display (normal)
 ; 5b00-5bef - screen data behind sprites (normal)
 ; 5bf0-9fff - pre-rotated sprite graphics
-; a000-afff - emulation code
-; b000-bfff - look-up tables
+; a000-b1ff - emulation code
+; b200-bfff - look-up tables
 ; c000-daff - Spectrum display (alt)
 ; db00-dbef - screen data behind sprites (alt)
 ; dbf0-ffff - pre-rotated tile graphics
@@ -718,7 +718,7 @@ do_input:      ld  de,&ffff         ; nothing pressed
                ld  a,&fe
                in  a,(keyboard)
                rra                  ; Shift?
-               jr  c,not_bright
+               jr  nc,not_bright
                set 6,c              ; use bright version
 not_bright:
 
@@ -961,7 +961,7 @@ tile_state:    ld  a,ixh
                bit 7,a              ; alt screen? (don't disturb carry!)
 
                jr  c,tile_strips    ; if any sprites are visible we'll draw in strips
-               jr  nz,fulldraw_alt     ; full screen draw (alt)
+               jr  nz,fulldraw_alt  ; full screen draw (alt)
 
 fulldraw_norm: ld  b,28
                ld  de,pac_chars
@@ -1576,7 +1576,7 @@ ELSE
                sub 16
 ENDIF
                dec d                ; red?
-               ret z
+               ret z                ; use bright red (sprite default)
 IF colour
 patch_add:     add a,0              ; restore original ghost sprite (0=colour, 16=mono)
 ELSE
@@ -1586,12 +1586,12 @@ ENDIF
                jr  nz,map_eyes
                srl d
                dec d                ; pink?
-               ld  c,&43            ; red
+               ld  c,&43            ; use bright magenta
                ret z
                dec d                ; cyan?
-               ld  c,&45
+               ld  c,&45            ; use bright cyan
                ret z
-               ld  c,&44            ; green (should be orange)
+               ld  c,&06            ; use yellow (should be orange)
                ret
 
 map_eyes:      ld  c,&47            ; bright white
@@ -2656,7 +2656,7 @@ msg_lp:        ld  a,(hl)
                jr  msg_lp
 
 
-loading_msg:   defm "pacemuzx v1.4"
+loading_msg:   defm "pacemuzx v1.5"
                defb 0
 
 specnet_msg:   defm "Disable Spectranet traps now..."
@@ -2950,13 +2950,11 @@ strip_lp:      ld  (hl),a           ; paint back to mono
                jr  strip_alt
 ENDIF
 
-end_a000:      equ $
-
-new_stack:     equ &b000            ; hangs back into &Axxx
+end_code:      equ $
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
-               org &b000
+               org &b200
 ; Tables are generated here at run time
 conv_8_6:      defs &100
 conv_x:        defs &100
@@ -2975,7 +2973,9 @@ ENDIF
 
 end_b000:      equ $
 
-               org &b000
+new_stack:     equ &c000            ; hangs back into &BFxx
+
+               org &b200
 ; Graphics are here at load time
 load_tiles:    incbin "tiles.bin"      ; 192 tiles * 6 lines * 1 byte per line = 1152 bytes
 load_sprites:  incbin "sprites.bin"    ; 76 sprites * 12 lines * 2 byte per line = 1824 bytes