pokecrystal/constants/hardware_constants.asm

; Graciously aped from:
; http://nocash.emubase.de/pandocs.htm
; http://gameboy.mongenel.com/dmg/asmmemmap.html

; memory map
VRAM_Begin  EQU $8000
VRAM_End    EQU $a000
SRAM_Begin  EQU $a000
SRAM_End    EQU $c000
WRAM0_Begin EQU $c000
WRAM0_End   EQU $d000
WRAM1_Begin EQU $d000
WRAM1_End   EQU $e000
; hardware registers $ff00-$ff80 (see below)
HRAM_Begin  EQU $ff80
HRAM_End    EQU $ffff

; MBC3
MBC3SRamEnable EQU $0000
MBC3RomBank    EQU $2000
MBC3SRamBank   EQU $4000
MBC3LatchClock EQU $6000
MBC3RTC        EQU $a000

SRAM_DISABLE EQU $00
SRAM_ENABLE  EQU $0a

NUM_SRAM_BANKS EQU 4

RTC_S  EQU $08 ; Seconds   0-59 (0-3Bh)
RTC_M  EQU $09 ; Minutes   0-59 (0-3Bh)
RTC_H  EQU $0a ; Hours     0-23 (0-17h)
RTC_DL EQU $0b ; Lower 8 bits of Day Counter (0-FFh)
RTC_DH EQU $0c ; Upper 1 bit of Day Counter, Carry Bit, Halt Flag
               ; Bit 0  Most significant bit of Day Counter (Bit 8)
               ; Bit 6  Halt (0=Active, 1=Stop Timer)
               ; Bit 7  Day Counter Carry Bit (1=Counter Overflow)

; interrupt flags
VBLANK   EQU 0
LCD_STAT EQU 1
TIMER    EQU 2
SERIAL   EQU 3
JOYPAD   EQU 4
IE_DEFAULT EQU (1 << SERIAL) | (1 << TIMER) | (1 << LCD_STAT) | (1 << VBLANK)

; OAM attribute flags
OAM_TILE_BANK EQU 3
OAM_OBP_NUM   EQU 4 ; non CGB Mode Only
OAM_X_FLIP    EQU 5
OAM_Y_FLIP    EQU 6
OAM_PRIORITY  EQU 7 ; 0: OBJ above BG, 1: OBJ behind BG (colors 1-3)

; BG Map attribute flags
PALETTE_MASK EQU %111
VRAM_BANK_1  EQU 1 << OAM_TILE_BANK ; $08
OBP_NUM      EQU 1 << OAM_OBP_NUM   ; $10
X_FLIP       EQU 1 << OAM_X_FLIP    ; $20
Y_FLIP       EQU 1 << OAM_Y_FLIP    ; $40
PRIORITY     EQU 1 << OAM_PRIORITY  ; $80

; Hardware registers
rJOYP       EQU $ff00 ; Joypad (R/W)
rSB         EQU $ff01 ; Serial transfer data (R/W)
rSC         EQU $ff02 ; Serial Transfer Control (R/W)
rSC_ON      EQU 7
rSC_CGB     EQU 1
rSC_CLOCK   EQU 0
rDIV        EQU $ff04 ; Divider Register (R/W)
rTIMA       EQU $ff05 ; Timer counter (R/W)
rTMA        EQU $ff06 ; Timer Modulo (R/W)
rTAC        EQU $ff07 ; Timer Control (R/W)
rTAC_ON        EQU 2
rTAC_4096_HZ   EQU 0
rTAC_262144_HZ EQU 1
rTAC_65536_HZ  EQU 2
rTAC_16384_HZ  EQU 3
rIF         EQU $ff0f ; Interrupt Flag (R/W)
rNR10       EQU $ff10 ; Channel 1 Sweep register (R/W)
rNR11       EQU $ff11 ; Channel 1 Sound length/Wave pattern duty (R/W)
rNR12       EQU $ff12 ; Channel 1 Volume Envelope (R/W)
rNR13       EQU $ff13 ; Channel 1 Frequency lo (Write Only)
rNR14       EQU $ff14 ; Channel 1 Frequency hi (R/W)
rNR20       EQU $ff15 ; Channel 2 Sweep register (R/W)
rNR21       EQU $ff16 ; Channel 2 Sound Length/Wave Pattern Duty (R/W)
rNR22       EQU $ff17 ; Channel 2 Volume Envelope (R/W)
rNR23       EQU $ff18 ; Channel 2 Frequency lo data (W)
rNR24       EQU $ff19 ; Channel 2 Frequency hi data (R/W)
rNR30       EQU $ff1a ; Channel 3 Sound on/off (R/W)
rNR31       EQU $ff1b ; Channel 3 Sound Length
rNR32       EQU $ff1c ; Channel 3 Select output level (R/W)
rNR33       EQU $ff1d ; Channel 3 Frequency's lower data (W)
rNR34       EQU $ff1e ; Channel 3 Frequency's higher data (R/W)
rNR40       EQU $ff1f ; Channel 4 Sweep register (R/W)
rNR41       EQU $ff20 ; Channel 4 Sound Length (R/W)
rNR42       EQU $ff21 ; Channel 4 Volume Envelope (R/W)
rNR43       EQU $ff22 ; Channel 4 Polynomial Counter (R/W)
rNR44       EQU $ff23 ; Channel 4 Counter/consecutive; Inital (R/W)
rNR50       EQU $ff24 ; Channel control / ON-OFF / Volume (R/W)
rNR51       EQU $ff25 ; Selection of Sound output terminal (R/W)
rNR52       EQU $ff26 ; Sound on/off
rWave_0     EQU $ff30
rWave_1     EQU $ff31
rWave_2     EQU $ff32
rWave_3     EQU $ff33
rWave_4     EQU $ff34
rWave_5     EQU $ff35
rWave_6     EQU $ff36
rWave_7     EQU $ff37
rWave_8     EQU $ff38
rWave_9     EQU $ff39
rWave_a     EQU $ff3a
rWave_b     EQU $ff3b
rWave_c     EQU $ff3c
rWave_d     EQU $ff3d
rWave_e     EQU $ff3e
rWave_f     EQU $ff3f
rLCDC       EQU $ff40 ; LCD Control (R/W)
rLCDC_BG_PRIORITY    EQU 0 ; 0=Off, 1=On
rLCDC_SPRITES_ENABLE EQU 1 ; 0=Off, 1=On
rLCDC_SPRITE_SIZE    EQU 2 ; 0=8x8, 1=8x16
rLCDC_BG_TILEMAP     EQU 3 ; 0=9800-9BFF, 1=9C00-9FFF
rLCDC_TILE_DATA      EQU 4 ; 0=8800-97FF, 1=8000-8FFF
rLCDC_WINDOW_ENABLE  EQU 5 ; 0=Off, 1=On
rLCDC_WINDOW_TILEMAP EQU 6 ; 0=9800-9BFF, 1=9C00-9FFF
rLCDC_ENABLE         EQU 7 ; 0=Off, 1=On
LCDC_DEFAULT EQU (1 << rLCDC_ENABLE) | (1 << rLCDC_WINDOW_TILEMAP) | (1 << rLCDC_WINDOW_ENABLE) | (1 << rLCDC_SPRITES_ENABLE) | (1 << rLCDC_BG_PRIORITY)
rSTAT       EQU $ff41 ; LCDC Status (R/W)
rSCY        EQU $ff42 ; Scroll Y (R/W)
rSCX        EQU $ff43 ; Scroll X (R/W)
rLY         EQU $ff44 ; LCDC Y-Coordinate (R)
LY_VBLANK EQU 144
rLYC        EQU $ff45 ; LY Compare (R/W)
rDMA        EQU $ff46 ; DMA Transfer and Start Address (W)
rBGP        EQU $ff47 ; BG Palette Data (R/W) - Non CGB Mode Only
rOBP0       EQU $ff48 ; Object Palette 0 Data (R/W) - Non CGB Mode Only
rOBP1       EQU $ff49 ; Object Palette 1 Data (R/W) - Non CGB Mode Only
rWY         EQU $ff4a ; Window Y Position (R/W)
rWX         EQU $ff4b ; Window X Position minus 7 (R/W)
rLCDMODE    EQU $ff4c
rKEY1       EQU $ff4d ; CGB Mode Only - Prepare Speed Switch
rVBK        EQU $ff4f ; CGB Mode Only - VRAM Bank
rBLCK       EQU $ff50
rHDMA1      EQU $ff51 ; CGB Mode Only - New DMA Source, High
rHDMA2      EQU $ff52 ; CGB Mode Only - New DMA Source, Low
rHDMA3      EQU $ff53 ; CGB Mode Only - New DMA Destination, High
rHDMA4      EQU $ff54 ; CGB Mode Only - New DMA Destination, Low
rHDMA5      EQU $ff55 ; CGB Mode Only - New DMA Length/Mode/Start
rRP         EQU $ff56 ; CGB Mode Only - Infrared Communications Port
rBGPI       EQU $ff68 ; CGB Mode Only - Background Palette Index
rBGPI_AUTO_INCREMENT EQU 7 ; increment rBGPI after write to rBGPD
rBGPD       EQU $ff69 ; CGB Mode Only - Background Palette Data
rOBPI       EQU $ff6a ; CGB Mode Only - Sprite Palette Index
rOBPI_AUTO_INCREMENT EQU 7 ; increment rOBPI after write to rOBPD
rOBPD       EQU $ff6b ; CGB Mode Only - Sprite Palette Data
rUNKNOWN1   EQU $ff6c ; (FEh) Bit 0 (Read/Write) - CGB Mode Only
rSVBK       EQU $ff70 ; CGB Mode Only - WRAM Bank
rUNKNOWN2   EQU $ff72 ; (00h) - Bit 0-7 (Read/Write)
rUNKNOWN3   EQU $ff73 ; (00h) - Bit 0-7 (Read/Write)
rUNKNOWN4   EQU $ff74 ; (00h) - Bit 0-7 (Read/Write) - CGB Mode Only
rUNKNOWN5   EQU $ff75 ; (8Fh) - Bit 4-6 (Read/Write)
rUNKNOWN6   EQU $ff76 ; (00h) - Always 00h (Read Only)
rUNKNOWN7   EQU $ff77 ; (00h) - Always 00h (Read Only)
rIE         EQU $ffff ; Interrupt Enable (R/W)
Keep memory map values in hardware_constants.asm 2017-12-27 04:18:05 +00:00			`; Graciously aped from:`
			`; http://nocash.emubase.de/pandocs.htm`
			`; http://gameboy.mongenel.com/dmg/asmmemmap.html`

			`; memory map`
			`VRAM_Begin EQU $8000`
			`VRAM_End EQU $a000`
			`SRAM_Begin EQU $a000`
			`SRAM_End EQU $c000`
			`WRAM0_Begin EQU $c000`
			`WRAM0_End EQU $d000`
			`WRAM1_Begin EQU $d000`
			`WRAM1_End EQU $e000`
			`; hardware registers $ff00-$ff80 (see below)`
			`HRAM_Begin EQU $ff80`
			`HRAM_End EQU $ffff`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00
MBC3 constants 2013-05-03 02:13:30 +00:00			`; MBC3`
			`MBC3SRamEnable EQU $0000`
			`MBC3RomBank EQU $2000`
			`MBC3SRamBank EQU $4000`
			`MBC3LatchClock EQU $6000`
			`MBC3RTC EQU $a000`

			`SRAM_DISABLE EQU $00`
			`SRAM_ENABLE EQU $0a`

split out constants 2013-06-11 01:56:34 +00:00			`NUM_SRAM_BANKS EQU 4`

MBC3 constants 2013-05-03 02:13:30 +00:00			`RTC_S EQU $08 ; Seconds 0-59 (0-3Bh)`
			`RTC_M EQU $09 ; Minutes 0-59 (0-3Bh)`
			`RTC_H EQU $0a ; Hours 0-23 (0-17h)`
			`RTC_DL EQU $0b ; Lower 8 bits of Day Counter (0-FFh)`
			`RTC_DH EQU $0c ; Upper 1 bit of Day Counter, Carry Bit, Halt Flag`
Fix whitespace alignment of comments 2020-09-27 16:31:07 +00:00			`; Bit 0 Most significant bit of Day Counter (Bit 8)`
			`; Bit 6 Halt (0=Active, 1=Stop Timer)`
			`; Bit 7 Day Counter Carry Bit (1=Counter Overflow)`
MBC3 constants 2013-05-03 02:13:30 +00:00
gbhw: flag constants for interrupts and timer registers 2013-08-28 03:37:24 +00:00			`; interrupt flags`
			`VBLANK EQU 0`
			`LCD_STAT EQU 1`
			`TIMER EQU 2`
			`SERIAL EQU 3`
			`JOYPAD EQU 4`
Fix usage of rIE and rSC constants 2019-05-05 16:14:46 +00:00			`IE_DEFAULT EQU (1 << SERIAL) \| (1 << TIMER) \| (1 << LCD_STAT) \| (1 << VBLANK)`
MBC3 constants 2013-05-03 02:13:30 +00:00
some oam constants 2013-12-01 21:40:56 +00:00			`; OAM attribute flags`
			`OAM_TILE_BANK EQU 3`
Identify some SPRITE_ANIM_FRAME_IDX_* constants 2017-12-12 06:34:46 +00:00			`OAM_OBP_NUM EQU 4 ; non CGB Mode Only`
some oam constants 2013-12-01 21:40:56 +00:00			`OAM_X_FLIP EQU 5`
			`OAM_Y_FLIP EQU 6`
			`OAM_PRIORITY EQU 7 ; 0: OBJ above BG, 1: OBJ behind BG (colors 1-3)`

Use more palette(s) constants 2018-01-01 13:47:16 +00:00			`; BG Map attribute flags`
Identify some SPRITE_ANIM_FRAME_IDX_* constants 2017-12-12 06:34:46 +00:00			`PALETTE_MASK EQU %111`
Identify more sprite-related constants Start more documentation 2017-12-12 18:22:19 +00:00			`VRAM_BANK_1 EQU 1 << OAM_TILE_BANK ; $08`
			`OBP_NUM EQU 1 << OAM_OBP_NUM ; $10`
			`X_FLIP EQU 1 << OAM_X_FLIP ; $20`
			`Y_FLIP EQU 1 << OAM_Y_FLIP ; $40`
Break up engine/events_3.asm 2018-01-12 04:50:44 +00:00			`PRIORITY EQU 1 << OAM_PRIORITY ; $80`
some oam constants 2013-12-01 21:40:56 +00:00
MBC3 constants 2013-05-03 02:13:30 +00:00			`; Hardware registers`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rJOYP EQU $ff00 ; Joypad (R/W)`
			`rSB EQU $ff01 ; Serial transfer data (R/W)`
			`rSC EQU $ff02 ; Serial Transfer Control (R/W)`
Identify some SPRITE_ANIM_FRAME_IDX_* constants 2017-12-12 06:34:46 +00:00			`rSC_ON EQU 7`
			`rSC_CGB EQU 1`
			`rSC_CLOCK EQU 0`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rDIV EQU $ff04 ; Divider Register (R/W)`
			`rTIMA EQU $ff05 ; Timer counter (R/W)`
			`rTMA EQU $ff06 ; Timer Modulo (R/W)`
			`rTAC EQU $ff07 ; Timer Control (R/W)`
gbhw: flag constants for interrupts and timer registers 2013-08-28 03:37:24 +00:00			`rTAC_ON EQU 2`
			`rTAC_4096_HZ EQU 0`
			`rTAC_262144_HZ EQU 1`
Trainer data structure and field move functions Trainer data in map scripts is now a macro-defined structure. Field move functions in main.asm are now nearly completely annotated, with local references. Trailing white space deleted. 2015-07-19 03:45:39 +00:00			`rTAC_65536_HZ EQU 2`
gbhw: flag constants for interrupts and timer registers 2013-08-28 03:37:24 +00:00			`rTAC_16384_HZ EQU 3`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rIF EQU $ff0f ; Interrupt Flag (R/W)`
			`rNR10 EQU $ff10 ; Channel 1 Sweep register (R/W)`
			`rNR11 EQU $ff11 ; Channel 1 Sound length/Wave pattern duty (R/W)`
			`rNR12 EQU $ff12 ; Channel 1 Volume Envelope (R/W)`
			`rNR13 EQU $ff13 ; Channel 1 Frequency lo (Write Only)`
			`rNR14 EQU $ff14 ; Channel 1 Frequency hi (R/W)`
Cleaning up static HRAM labels; movement stuff, route 38 trainers 2015-11-10 04:01:45 +00:00			`rNR20 EQU $ff15 ; Channel 2 Sweep register (R/W)`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rNR21 EQU $ff16 ; Channel 2 Sound Length/Wave Pattern Duty (R/W)`
			`rNR22 EQU $ff17 ; Channel 2 Volume Envelope (R/W)`
			`rNR23 EQU $ff18 ; Channel 2 Frequency lo data (W)`
			`rNR24 EQU $ff19 ; Channel 2 Frequency hi data (R/W)`
			`rNR30 EQU $ff1a ; Channel 3 Sound on/off (R/W)`
			`rNR31 EQU $ff1b ; Channel 3 Sound Length`
			`rNR32 EQU $ff1c ; Channel 3 Select output level (R/W)`
			`rNR33 EQU $ff1d ; Channel 3 Frequency's lower data (W)`
			`rNR34 EQU $ff1e ; Channel 3 Frequency's higher data (R/W)`
Cleaning up static HRAM labels; movement stuff, route 38 trainers 2015-11-10 04:01:45 +00:00			`rNR40 EQU $ff1f ; Channel 4 Sweep register (R/W)`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rNR41 EQU $ff20 ; Channel 4 Sound Length (R/W)`
			`rNR42 EQU $ff21 ; Channel 4 Volume Envelope (R/W)`
			`rNR43 EQU $ff22 ; Channel 4 Polynomial Counter (R/W)`
			`rNR44 EQU $ff23 ; Channel 4 Counter/consecutive; Inital (R/W)`
			`rNR50 EQU $ff24 ; Channel control / ON-OFF / Volume (R/W)`
			`rNR51 EQU $ff25 ; Selection of Sound output terminal (R/W)`
			`rNR52 EQU $ff26 ; Sound on/off`
Cleaning up static HRAM labels; movement stuff, route 38 trainers 2015-11-10 04:01:45 +00:00			`rWave_0 EQU $ff30`
			`rWave_1 EQU $ff31`
			`rWave_2 EQU $ff32`
			`rWave_3 EQU $ff33`
			`rWave_4 EQU $ff34`
			`rWave_5 EQU $ff35`
			`rWave_6 EQU $ff36`
			`rWave_7 EQU $ff37`
			`rWave_8 EQU $ff38`
			`rWave_9 EQU $ff39`
			`rWave_a EQU $ff3a`
			`rWave_b EQU $ff3b`
			`rWave_c EQU $ff3c`
			`rWave_d EQU $ff3d`
			`rWave_e EQU $ff3e`
			`rWave_f EQU $ff3f`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rLCDC EQU $ff40 ; LCD Control (R/W)`
More LCDC bit constants 2018-07-06 02:00:13 +00:00			`rLCDC_BG_PRIORITY EQU 0 ; 0=Off, 1=On`
Clean up changes in 3c6c80f 2017-12-29 18:22:33 +00:00			`rLCDC_SPRITES_ENABLE EQU 1 ; 0=Off, 1=On`
			`rLCDC_SPRITE_SIZE EQU 2 ; 0=8x8, 1=8x16`
More LCDC bit constants 2018-07-06 02:00:13 +00:00			`rLCDC_BG_TILEMAP EQU 3 ; 0=9800-9BFF, 1=9C00-9FFF`
			`rLCDC_TILE_DATA EQU 4 ; 0=8800-97FF, 1=8000-8FFF`
			`rLCDC_WINDOW_ENABLE EQU 5 ; 0=Off, 1=On`
Clean up changes in 3c6c80f 2017-12-29 18:22:33 +00:00			`rLCDC_WINDOW_TILEMAP EQU 6 ; 0=9800-9BFF, 1=9C00-9FFF`
			`rLCDC_ENABLE EQU 7 ; 0=Off, 1=On`
More LCDC bit constants 2018-07-06 02:00:13 +00:00			`LCDC_DEFAULT EQU (1 << rLCDC_ENABLE) \| (1 << rLCDC_WINDOW_TILEMAP) \| (1 << rLCDC_WINDOW_ENABLE) \| (1 << rLCDC_SPRITES_ENABLE) \| (1 << rLCDC_BG_PRIORITY)`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rSTAT EQU $ff41 ; LCDC Status (R/W)`
			`rSCY EQU $ff42 ; Scroll Y (R/W)`
			`rSCX EQU $ff43 ; Scroll X (R/W)`
			`rLY EQU $ff44 ; LCDC Y-Coordinate (R)`
More LCDC bit constants 2018-07-06 02:00:13 +00:00			`LY_VBLANK EQU 144`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rLYC EQU $ff45 ; LY Compare (R/W)`
			`rDMA EQU $ff46 ; DMA Transfer and Start Address (W)`
			`rBGP EQU $ff47 ; BG Palette Data (R/W) - Non CGB Mode Only`
			`rOBP0 EQU $ff48 ; Object Palette 0 Data (R/W) - Non CGB Mode Only`
			`rOBP1 EQU $ff49 ; Object Palette 1 Data (R/W) - Non CGB Mode Only`
			`rWY EQU $ff4a ; Window Y Position (R/W)`
			`rWX EQU $ff4b ; Window X Position minus 7 (R/W)`
A stab at audio engine. 2015-12-07 03:36:09 +00:00			`rLCDMODE EQU $ff4c`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rKEY1 EQU $ff4d ; CGB Mode Only - Prepare Speed Switch`
			`rVBK EQU $ff4f ; CGB Mode Only - VRAM Bank`
A stab at audio engine. 2015-12-07 03:36:09 +00:00			`rBLCK EQU $ff50`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rHDMA1 EQU $ff51 ; CGB Mode Only - New DMA Source, High`
			`rHDMA2 EQU $ff52 ; CGB Mode Only - New DMA Source, Low`
			`rHDMA3 EQU $ff53 ; CGB Mode Only - New DMA Destination, High`
			`rHDMA4 EQU $ff54 ; CGB Mode Only - New DMA Destination, Low`
			`rHDMA5 EQU $ff55 ; CGB Mode Only - New DMA Length/Mode/Start`
			`rRP EQU $ff56 ; CGB Mode Only - Infrared Communications Port`
			`rBGPI EQU $ff68 ; CGB Mode Only - Background Palette Index`
Use constants for rBGPI+rOBPI auto-increment Fix some documentation 2018-01-01 18:43:02 +00:00			`rBGPI_AUTO_INCREMENT EQU 7 ; increment rBGPI after write to rBGPD`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rBGPD EQU $ff69 ; CGB Mode Only - Background Palette Data`
			`rOBPI EQU $ff6a ; CGB Mode Only - Sprite Palette Index`
Use constants for rBGPI+rOBPI auto-increment Fix some documentation 2018-01-01 18:43:02 +00:00			`rOBPI_AUTO_INCREMENT EQU 7 ; increment rOBPI after write to rOBPD`
Add constants for hardware registers 2013-02-20 05:05:07 +00:00			`rOBPD EQU $ff6b ; CGB Mode Only - Sprite Palette Data`
			`rUNKNOWN1 EQU $ff6c ; (FEh) Bit 0 (Read/Write) - CGB Mode Only`
			`rSVBK EQU $ff70 ; CGB Mode Only - WRAM Bank`
			`rUNKNOWN2 EQU $ff72 ; (00h) - Bit 0-7 (Read/Write)`
			`rUNKNOWN3 EQU $ff73 ; (00h) - Bit 0-7 (Read/Write)`
			`rUNKNOWN4 EQU $ff74 ; (00h) - Bit 0-7 (Read/Write) - CGB Mode Only`
			`rUNKNOWN5 EQU $ff75 ; (8Fh) - Bit 4-6 (Read/Write)`
			`rUNKNOWN6 EQU $ff76 ; (00h) - Always 00h (Read Only)`
			`rUNKNOWN7 EQU $ff77 ; (00h) - Always 00h (Read Only)`
			`rIE EQU $ffff ; Interrupt Enable (R/W)`