Memory Map

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The HuC6280 processor provides a 21bit address bus on the TurboGrafx allowing contiguous addressing of up to 2MB. The address space is divided into 256 8KB pages.
 Start Address  End Address  Pages  Size*  Description
 0x000000  0x0FFFFF  0x00 – 0x7F  1MB  HuCard ROM Space (may be mirrored with HuCards smaller than 1MB)
 0x100000  0x1EEFFF  0x80 – 0xF7  Unused, see CD-ROM info
 0x1F0000  0x1F7FFF  0xF8 – 0xFB  8KB  RAM – pages 0xF9 – 0xFB are mirrors of 0xF8
 0x1F8000  0x1FDFFF  0xFC – 0xFE  Unused
 0x1FE000  0x1FFFFF  0xFF  8KB  Hardware Page
*size refers to the useful size within the range, excluding any mirroring

Super System Card

 Start Address  End Address  Pages  Size*  Description
 0x000000  0x0CFFFF  0x00 – 0x67  832KB  ROM Space
 0x0D0000  0x0FFFFF  0x68 – 0x7F  192KB  RAM

Hardware Page

Start Address  End Address  Description
 0x0000  0x03FF  Video Display Controller – mirrored every 4 bytes
 0x0400  0x07FF  Video Colour Encoder – mirrored every 8 bytes
 0x0800  0x0BFF  Programmable Sound Generator
 0x0C00  0x0FFF  Timer – mirrored every 2 bytes
 0x1000  0x17FF  I/O Port – mirrored every byte
 0x1400  0x17FF  Interrupt control – mirrored every 4 bytes
 0x1800  0x1BFF  See CD-ROM info
 0x1C00  0x1FFF  Unused – always returns 0xFF


The TurboGrafx-CD consists of the following memory:
  • 64KB RAM
  • 2KB Battery-backed RAM
 Start Address  End Address  Pages  Size*  Description
 0x100000  0x10FFFF  0x80 – 0x87  64KB  CD RAM
 0x1EE000  0x1EE7FF  0xF7  2KB  Battery-backed RAM

CD-ROM Registers

Address  Page  Description
 0x1800  0xFF  CDC Status
 0x1801  0xFF  CDC Command / Status / Data
 0x1802  0xFF  ADPCM / CD Control
 0x1803  0xFF  BRAM Lock / CD Status
 0x1804  0xFF  CD Reset
 0x1805  0xFF  Convert PCM Data / PCM Data
 0x1806  0xFF  PCM Data
 0x1807  0xFF  BRAM Unlock / CD Status
 0x1808  0xFF  ADPCM Address (LSB) / CD Data
 0x1809  0xFF  ADPCM Address (MSB)
 0x180A  0xFF  ADPCM RAM Data Port
 0x180B  0xFF  ADPCM DMA Control
 0x180C  0xFF  ADPCM Status
 0x180D  0xFF  ADPCM Address Control
 0x180E  0xFF  ADPCM Playback Rate
 0x180F  0xFF  ADPCM and CD Audio Fade Timer


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