PM_Bios

The BIOS Overview

The internal BIOS consists of a 4kB program image built to initialize the system, bring it out of sleep and various other system specific tasks. Since the Pokemon Mini is never technically off, only suspended, BIOS is used for tasks like enabling power to the system and responding to various at rest IRQs.

The BIOS image begins with a 256 byte IRQ vector table, consisting of 128 16-bit vectors (only first 76 are valid). The system reserves 32 vectors for hardware IRQs, the rest are used for software calls. It is worth noting that all IRQs are latched on the rising edge of an event, so button presses and IR receive is only latched when the IR receiver is active 1 or if a button has been press, but not released.

The IRQ Vector Table

Bios IRQ Vector Table

IRQ	BIOS	Cart IRQ	IRQ Group	Hardware Strobe	Description
$00	0000:009A	0	Non-Maskable	System Start-up / System Reset
$01	0002:00AB		Non-Maskable	Unused
$02	0004:00AB		Non-Maskable	Unused
$03	0006:01CF	1	$20[7..6]	$27,7	PRC Copy Complete
$04	0008:01E0	2	$20[7..6]	$27,6	PRC Frame Divider Overflow
$05	000A:01F1	3	$20[5..4]	$27,5	Timer2 Upper-8 Underflow
$06	000C:0202	4	$20[5..4]	$27,4	Timer2 Lower-8 Underflow (8-bit only)
$07	000E:0213	5	$20[3..2]	$27,3	Timer1 Upper-8 Underflow
$08	0010:0224	6	$20[3..2]	$27,2	Timer1 Lower-8 Underflow (8-bit only)
$09	0012:0235	7	$20[1..0]	$27,1	Timer3 Upper-8 Underflow
$0A	0014:0246	8	$20[1..0]	$27,0	Timer3 Pivot
$0B	0016:025A	9	$21[7..6]	$28,5	32Hz (From 256Hz Timer)
$0C	0018:026B	10	$21[7..6]	$28,4	8Hz (From 256Hz Timer)
$0D	001A:027C	11	$21[7..6]	$28,3	2Hz (From 256Hz Timer)
$0E	001C:028D	12	$21[7..6]	$28,2	1Hz (From 256Hz Timer)
$0F	001E:029E	13	$22[1..0]	$2A,7	IR Receiver
$10	0020:02AF	14	$22[1..0]	$2A,6	Shock Sensor
$11	0022:00AB			$2A,5	Unused
$12	0024:00AB			$2A,4	Unused
$13	0026:043E		$21[5..4]	$28,1	Cartridge Ejected
$14	0028:02C0	26	$21[5..4]	$28,0	Cartridge IRQ
$15	002A:03BA	15	$21[3..2]	$29,7	Power Key
$16	002C:02D1	16	$21[3..2]	$29,6	Right Key
$17	002E:02E2	17	$21[3..2]	$29,5	Left Key
$18	0030:02F3	18	$21[3..2]	$29,4	Down Key
$19	0032:0304	19	$21[3..2]	$29,3	Up Key
$1A	0034:0315	20	$21[3..2]	$29,2	C Key
$1B	0036:0326	21	$21[3..2]	$29,1	B Key
$1C	0038:0337	22	$21[3..2]	$29,0	A Key
$1D	003A:0348	23		$2A,2
$1E	003C:035C	24		$2A,1
$1F	003E:036D	25		$2A,0
IRQ	BIOS	(Software only) Description
$20	0040:FFF1	User IRQ Routine at PC 0xFFF1
$21	0042:0713	Suspend System
$22	0044:077C	Sleep ??
$23	0046:078B	Sleep with display on ??
$24	0048:079D	Shutdown System (Use this to exit your game!)
$25	004A:07B1	?? (Involves Cartridge Eject)
$26	004C:07E9	Set default LCD Constrast (A = Contrast level 0x00 to 0x3F)
$27	004E:0802	Increase or decrease Contrast based of Zero flag (0 = Increase, 1 = Decrease) Return A = 0x00 if succeed, 0xFF if not.
$28	0050:081B	Apply default LCD Constrast
$29	0052:0821	Get default LCD Contrast (return A)
$2A	0054:0830	Set temporary LCD Constrast (A = Contrast level 0x00 to 0x3F)
$2B	0056:084E	Turn LCD On
$2C	0058:0871	Initialize LCD
$2D	005A:08CB	Turn LCD Off
$2E	005C:08EC	Enable RAM vector. (Check if Register 0x01 Bit 7 is set, if not, it set bit 6 and 7)
$2F	005E:0904	Disable RAM vector
$30	0060:0923	Disable Cart Eject IRQ 13 (with abort)
$31	0062:092E	Enable Cart Eject IRQ 13 (with abort)
$32	0064:0949	?? (Involves Cartridge Eject)
$33	0066:0961	?? (Involves Cartridge Eject)
$34	0068:097D	Nintendo Dev Card (??)
$35	006A:09E4	Nintendo Dev Card (??)
$36	006C:0A4F	?? (Involves Cartridge Eject)
$37	006E:0A76	Disable Cartridge Eject IRQ (Reg 0x24, Bit 1 = 0)
$38	0070:0A81	?? (Involves Cartridge Eject)
$39	0072:0AA6	Rumored to speed up CPU?
$3A	0074:0ACD	Recover from IRQ $39?
$3B	0076:0AE6	Cart power off and update state
$3C	0078:0AF9	Cart power on and update state
$3D	007A:0B20	Cart detect. Z: No cart, NZ: Cart inserted (Test Register 0x53 Bit 1 and invert Zero flag)
$3E	007C:0B2E	Read structure, write 0xFF, compare values and optionally jump to subroutine X point to a structure in memory: structure {  byte   type            ; 0x01 = Call subroutine, 0x00 = Don't call subroutine  triple write_0xFF_addr ; Address that 0xFF will be written  triple compare_addr    ; Address to read for compare  byte   compare_value   ; Value that must match the compare  triple subroutine      ; Use byte POP to receive flag of the compare } if type is 0x00, register A return 0x01 if compare is equal
$3F	007E:0B8F	Set PRC Rate (A = 0 to 7)
$40	0080:0BA3	Get PRC Rate (return A)
$41	0082:0BB1	Test cart type. Returns Z: non multi cart, NZ: multi cart (Register 0x01 Bit 3)
$42	0084:047A	Nintendo Dev Card (Read IDs)
$43	0086:0493	Nintendo Dev Card (Reset)
$44	0088:04A4	Nintendo Dev Card (Program Byte)
$45	008A:04C8	Nintendo Dev Card (Erase Sector)
$46	008C:04F5	Nintendo Dev Card (Unlock flash page register. Command 0xD0)
$47	008E:0506	Nintendo Dev Card (Select flash bank. A=bank Nr, X last address of flash page)
$48	0090:0517	Nintendo Dev Card (Command 0xC9)
$49	0092:0529	Nintendo Dev Card (Prepare Manufacturer and device ID readout. Command 0xC0)
$4A	0094:053A	Nintendo Dev Card (Select flash game. A = game Nr. ([0x041048 + 96 * A] if 0x08 -> Command 0xC9)
$4B	0096:0000	Nintendo SDK
$4C	0098:0BBD	IR pulse MOV [Y], $02 ; wait B*16 Cycles ; MOV [Y], $00