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BIOS Functions

The Loopy's built-in ROM provides code for common operations such as drawing graphics, playing music, and operating the printer.

This page is intended to list and categorize these functions with brief descriptions. Workflows like adding music and graphics to your homebrew game will be their own separate pages.

This google sheet was adapted as the starting point.

Uncategorized

TODO categorize these

(TBD) Default Interrupt Handler

Offset: 0x0604

Turns off printer? and halts

BiosVdpMode

Offset: 0x668

Sets VDP controller scanning mode and video height

BiosGetSealType

BiosDecompress4bit

BiosInitSoundTransmission

BiosPlayBgm

BiosPlaySfx

BiosUpdateBgm

BiosDma

BiosVsyncIfDma

BiosVsyncDma

BiosVsync

BiosSoundChannels

BiosSoundVolume

BiosSoundDemo

Unidentified Decompressor

Interrupt Handlers

BiosAutoUpdateBgm

Math Functions

BiosColorInverseGray

BiosValueBlendQuarter

BiosColorBlendQuarter

BiosMulS16

BiosMulU16

BiosDivU16

BiosDivS16

BiosDivS32

Graphics

BiosPlotLines

BiosPlotPolygons (TBD)

Internal Use

_B_PrintOp1

_B_PlotPointInBuffer

_B_PlotPointSpecial

_B_PlayBgmPointer

_B_PlaySfxPointer

Not yet analyzed

0x069C
0x0FD6
0x101C
0x1064
0x10AC
0x10F4
0x1140
0x1174
0x1198
0x1248
0x128E
0x134C
0x13B0
0x1408
0x1464
0x157E
0x15D4
0x15F2
0x15FE
0x162C
0x1652
0x1662
0x1690
0x17F4
0x19BC
0x1A0C
0x1B76
0x1B9C
0x1C04
0x1C2C
0x1CA0
0x1CF4
0x1DDE
0x1E1C
0x1F5E
0x2038
0x20EC
0x212E
0x2148
0x2382
0x2598
0x2798
0x2A24
0x2AD0
0x2B0E
0x2B48
0x2F74
0x3088
0x3560
0x35E6
0x36BA
0x3736
0x3E64
0x3E9C
0x3EF0
0x3F48
0x3FD8
0x40DC
0x4186
0x429C
0x436A
0x445C
0x452C
0x4640
0x47A4
0x49A4
0x4B20
0x4BA8
0x4C38
0x4CDE
0x4D22
0x4E34
0x4FE4
0x5060
0x5098
0x5138
0x51C8
0x542E
0x544C
0x5474
0x54B8
0x5574
0x55B8
0x55FC

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