The file system used on the Xbox is [[FATX]], a variant of FAT16/32 developed by Microsoft specifically for the Xbox.

== Implementations ==

{| class="wikitable
|-
! Name
! Platform
! Read/Write
! Description
|-
| Official
| Xbox
| Read/Write
| Official FATX implementation by Microsoft
|-
| [https://github.com/mborgerson/fatx fatxfs]
| GNU/Linux, macOS
| Read-Only
| [https://en.wikipedia.org/wiki/Filesystem_in_Userspace FUSE]-based implementation
|}

== Further Reading ==
* [http://hackipedia.org/Disk%20formats/File%20systems/FATX%2C%20File%20Allocation%20Table%20%28X-Box%29/Differences_between_Xbox_FATX_and_MS-DOS_FAT.htm Differences between Xbox FATX and MS-DOS FAT]
* [https://web.archive.org/web/20020617181617/http://www.tardis.ed.ac.uk:80/~lucien/computing/projects/xbox/XBOX-disk-layout.htm XBOX DISK LAYOUT v0.13]

DSP

2018-12-27T11:05:50Z

Espes:

The DSPs in the APU are probably "Parthus MediaStream" DSP cores (probably the 24-bit DSP2420 "Mozart" core).

Those are similar to Motorola DSP56362 (DSP56300 Family). If so, the datasheet can be found at http://www.nxp.com/docs/en/data-sheet/DSP56362.pdf (Also see "Documentation" section in said datasheet for the related documentation)

== Memory Size ==

{| class="wikitable"
|-
!
! Program RAM Size
! X Data RAM Size
! Y Data RAM Size
! MIXBUF Size
|-
! GP
| 4096 x 24-bit
| 4096 x 24-bit
| 2048 x 24-bit
| 992{{FIXME|reason=This is probably 1024 words, but the last 32 words were not working as intended during my testing}} x 24-bit
|-
! EP
| 4096 x 24-bit
| 3072 x 24-bit
| 256 x 24-bit
| n/a
|}

MIXBUF is accessible at X:$001400 in the GP.

Other datasheets for similar DSPs suggest that the memory sizes might be different if instruction cache or switch mode are toggled.
It is currently unknown if the DSPs in the Xbox APU support a similar feature{{FIXME}}.

== DMA ==

''This section is very incomplete and not much was tested on hardware either''

DMA is controlled using peripheral registers:

* 0xFFFFD4: Memory address of next command block
* 0xFFFFD5: DMA_START_BLOCK{{FIXME|reason=How is this used?}}
* 0xFFFFD6: DMA_CONTROL{{FIXME|reason=Explain the bits}}
* 0xFFFFD7: DMA_CONFIGURATION{{FIXME|reason=Explain the bits}}

Additionally, bit 7 in the interrupt register at 0xFFFFC5 is set if a DMA End-Of-List has been encountered.

=== Command blocks ===

DSP command blocks are loaded from X-Memory.

{| class="wikitable"
! Word
! Meaning
! Notes
|-
! 0
| Next command block address || Memory address of next command block.
Bit 14 is used as End-Of-List marker.
|-
! 1
| Transfer control word || Controls the DMA transfer:

* Unknown (Bit-offset 0; 1-bit).
** 0 = ?
** 1 = ?

* Direction (Bit-offset 1; 1-bit).
** 0 = Buffer to DSP
** 1 = DSP to buffer

* Unknown (Bit-offset 2; 2-bit).
** 0 = ?
** 1 = ?
** 2 = ?
** 3 = ?

* Buffer offset writeback (Bit-offset 4; 1-bit).
** 0 = Don't update buffer offset (Word 4)
** 1 = Update buffer offset (Word 4); this respects address wrapping of circular buffers

* Buffer (Bit-offset 5; 4-bits).
** 0x0 = FIFO0
** 0x1 = FIFO1
** 0x2 = FIFO2{{citation needed}}
** 0x3 = FIFO3{{citation needed}}
** 0x4
** 0x5
** 0x6
** 0x7
** 0x8
** 0x9
** 0xA
** 0xB
** 0xC
** 0xD
** 0xE = Scratch-Circular
** 0xF = Scratch

* Unknown (Bit-offset 9; 1-bit).
** 0 = ?
** 1 = ?

* Sample format (Bit-offset 10; 3-bits).{{FIXME|reason=Some of these need tests with signed datatypes}}
** 0x0 = 8 bit (1 DSP word / 1 byte); ''sample-count must be multiple of 4, or transfer is skipped; rounded; byte MSB is flipped''
*** Buffer to DSP: bytes: <code>0x12,0x34,0x56,0x78</code> → words: <code>0x920000, 0xB40000, 0xD60000, 0xF80000</code>
*** Buffer to DSP: bytes: <code>0x92,0xB4,0xD6,0xF8</code> → words: <code>0x120000, 0x340000, 0x560000, 0x780000</code>
*** DSP to buffer: words: <code>0x927FFF, 0xB47FFF, 0xD67FFF, 0xF87FFF</code> → bytes: <code>0x12,0x34,0x56,0x78</code> ''(Rounded down)''
*** DSP to buffer: words: <code>0x928000, 0xB48000, 0xD68000, 0xF88000</code> → bytes: <code>0x13,0x35,0x57,0x79</code> ''(Rounded up)''
*** DSP to buffer: words: <code>0x800000, 0x7E7FFF, 0x7E8000, 0x7FFFFF</code> → bytes: <code>0x00,0xFE,0xFF,0xFF</code> ''(Saturated)''
** 0x1 = 16 bit (1 DSP word / 2 bytes) ''sample-count must be multiple of 2, or transfer is skipped; truncated''
*** Buffer to DSP: bytes: <code>0x34,0x12</code> → word: <code>0x123400</code>
*** DSP to buffer: word: <code>0x1234FF</code> → bytes: <code>0x34,0x12</code> ''(Truncated)''
*** DSP to buffer: word: <code>0x123400</code> → bytes: <code>0x34,0x12</code> ''(Truncated)''
** 0x2 = 24 bit in MSB (1 DSP word / 4 bytes); ''padded''
*** Buffer to DSP: bytes: <code>0x00,0x56,0x34,0x12</code> → word: <code>0x123456</code> ''(Padding ignored)''
*** Buffer to DSP: bytes: <code>0xFF,0x56,0x34,0x12</code> → word: <code>0x123456</code> ''(Padding ignored)''
*** DSP to buffer: word: <code>0x123456</code> → bytes: <code>0x00,0x56,0x34,0x12</code> ''(Zero padding)''
** 0x3 = 32 bit (2 DSP words / 4 bytes); ''trunacted''
*** Buffer to DSP: bytes: <code>0x12,0xBC,0x9A,0x78</code> → words: <code>0x120000, 0x789ABC</code>
*** DSP to buffer: words: <code>0x12FFFF, 0x789ABC</code> → bytes: <code>0x12,0xBC,0x9A,0x78</code> ''(Truncated)''
*** DSP to buffer: words: <code>0x120000, 0x789ABC</code> → bytes: <code>0x12,0xBC,0x9A,0x78</code> ''(Truncated)''
** 0x4 = ''Transfer skipped''
** 0x5 = ''Transfer skipped''
** 0x6 = 24 bit in LSB (1 DSP word / 4 bytes); ''padded''
*** Buffer to DSP: bytes: <code>0x56,0x34,0x12,0x00</code> → word: <code>0x123456</code> ''(Padding ignored)''
*** Buffer to DSP: bytes: <code>0x56,0x34,0x12,0xFF</code> → word: <code>0x123456</code> ''(Padding ignored)''
*** DSP to buffer: word: <code>0x123456</code> → bytes: <code>0x56,0x34,0x12,0x00</code> ''(Zero padding)''
** 0x7 = ''Transfer skipped''

* Unknown (Bit-offset 13; 1-bit).
** 0 = ?
** 1 = ?

* DSP address step size (Bit-offset 14; unknown size).
** Each DSP word is addressed using <code>dsp_address + sample_index * step_size</code>

|-
! 2
| Transfer sample count || The number of samples to transfer.
|-
! 3
| DSP address || This is the address in the DSP:
* 0x0000 - 0x17FF = X-Memory
* 0x1800 - 0x27FF = Y-Memory
* 0x2800 - 0x37FF = P-Memory
|-
! 4
| Buffer offset || This is the address within the buffer where the first sample is accessed.
|-
! 5
| Buffer base || ''Only used for circular buffers, ignored otherwise.''{{FIXME|reason=Assumption; it happens for buffer 0xE, but not for buffer 0xF}}
The start of the buffer.
|-
! 6
| Buffer size || ''Only used for circular buffers, ignored otherwise.''{{FIXME|reason=Assumption; it happens for buffer 0xE, but not for buffer 0xF}}
Size of buffer minus 1. For a buffer with 0x1000 bytes, this has to be 0xFFF.
|}

== Related links ==

* [https://github.com/XboxDev/a56 Modernized fork of a56, open-source assembler for the similar 56000 architecture]
* [https://web.archive.org/web/20010212122052/http://www.parthus.com:80/platforms/parthus_mediastream/index.html MediaStream product page]
* [https://web.archive.org/web/20011130084353/http://www.fs2.com:80/parthus_download/ First Silicon MediaStream tools]
* [https://web.archive.org/web/20020213235936/http://www.tasking.com/products/MediaStream/index.html Tasking MediaStream compiler]

2017-05-26T18:39:20Z

Espes:

<div style="background-color:#e7eef6; border: 1px solid #ccc; color:#000; margin-top: 15px; margin-bottom: 10px; padding: 8px; text-align:center;">
<div style="font-size: 162%; border: none; margin: 0; padding:.1em;">Welcome to XboxDevWiki.net,</div>
<div style="font-size: 95%">a wiki dedicated to research of the original Microsoft Xbox.</div>
<div style="text-align:left;">

<hr>

This is an effort to document the inner workings of the original Microsoft Xbox and Xbox-based SEGA Chihiro.
We not only care about technical details about those platforms, but also how to develop homebrew and emulate them.

We are not interested in documenting the Xbox 360, Xbox One or any other console at this point.

<hr>

This wiki will become the place for all remaining Xbox projects to come together.
If you are interested in helping or discussing this, please come chat with us in #xqemu on freenode or Cxbx-Reloaded/Lobby on gitter.im.
</div>
</div>

Emulators

2017-05-26T18:38:21Z

Espes:

This is a list of known Xbox emulation projects

{| class="wikitable sortable"
!Status
!Approach
!Name
!Links
!Initiator
!Platform
!License
!Notes
|-
|Maintained
|LLE
|[[XQEMU]]
|
|espes
|Windows/Linux/Mac/Others
|
|XQEMU supports hardware-acceleration for the CPU emulation on Linux through KVM.
|-
|Maintained
|HLE
|[[Cxbx-Reloaded]]
|
|SoullessSentinel
|Windows
|
|At the time of writing Cxbx-Reloaded is almost purely HLE. LLE GPU emulation is planned, but currently not implemented.
|-
|Dead
|HLE
|[[Cxbx]]
|
|Caustik
|Windows
|
|
|-
|Dead
|HLE
|Dxbx
|[http://dxbx-emu.com][https://github.com/PatrickvL/Dxbx/]
|ShadowTj
|Windows
|
|The project was started on March 23rd 2008. It is an improved port of Cxbx to the Delphi programming language.
|-
|Unknown
|Unknown
|[https://github.com/impeachgod/Dirtbox Dirtbox]
|
|
|Windows
|
|
|-
|Unknown
|HLE
|[https://sourceforge.net/p/ironbabel/code/HEAD/tree/trunk/Box/Xbox/ IronBabel]
|
|daeken
|Unknown
|
|This seems to have been a generic portability framework
|-
|Unknown
|HLE
|[https://github.com/daeken/Steelbreeze Steelbreeze]
|
|daeken
|Unknown
|
|
|-
|Unknown
|LLE/HLE Hybrid
|[https://github.com/daeken/Zookeeper Zookeeper]
|
|daeken
|Unknown
|
|
|-
|Unknown
|Unknown
|[http://ngemu.com/threads/.154342/ XbeNext]
|
|LoveMHz
|Windows
|
|
|-
|Dead
|HLE
|[http://ngemu.com/forums/.65/ Xeon]
|
|
|Windows
|
|
|-
|Unknown
|Unknown
|[http://ngemu.com/threads/.105210/ XProject]
|
|
|Windows
|
|
|-
|Unknown
|Unknown
|[https://code.google.com/p/xbem xbem]
|
|
|Windows
|
|
|-
|Dead
|LLE/HLE Hybrid
|Hackbox
|
|JayFoxRox
|Windows/Linux
|Private
|This was originally going to be a commercial emulator (but plans were dropped quickly in favor of preservation). The source code was temporarily public but then made private. The source code is still available to a selected group of developers. Hackbox was designed from scratch but re-used code from Cxbx for HLE routine detection.
|-
|Unknown
|LLE
|[https://github.com/phire/kvmbox kvmbox]
|
|phire
|Linux
|
|
|-
|Unknown
|HLE
|[https://github.com/Gabriel-Maldonado/XboxHLE XboxHLE]
|
|
|Windows
|
|
|-
|Unknown
|Unknown
|[https://github.com/bjh83/boombox boombox]
|
|
|Windows
|
|
|-
|Unknown
|Unknown
|[https://github.com/docbrown/vxb vxb]
|
|
|Windows
|
|
|-
|Unknown
|Unknown
|[https://github.com/quantumdude836/exciplex exciplex]
|
|
|Windows
|
|
|-
|Maintained
|LLE
|[http://mamedev.org/ MAME/Chihiro]
|
|MAME Team
|Windows/Linux/Mac/Others
|
|
|-
|Unknown
|LLE
|[http://mamedev.org/ MAME/Xbox]
|
|MAME Team
|Windows/Linux/Mac/Others
|
|Does this exist yet?{{citation needed}}
|-
|Dead
|Unknown
|[https://github.com/monocasa/xbvm XBVM]
|
|
|Windows
|
|
|-
|Dead
|
|[http://xenoborg-emu.blogspot.com/ Xenoborg]
|
|blueshogun96
|Windows
|
|
|-
|Dead
|Unknown
|[[Xbox 360 Backward Compatibility]]
|
|Microsoft
|Xbox 360
|Proprietary
|
|}

== References and links ==

* [https://www.reddit.com/r/emulation/comments/6a958p/cxbx_reloaded_xbox_emulator_panzer_dragoon_orta/ Discussion about Xbox emulation and technical differences between [[Cxbx-Reloaded]] and [[XQEMU]]]

EEPROM

2017-05-25T19:01:36Z

Espes:

The EEPROM of the Xbox is connected via I²C and located on address 0x54.
The EEPROM is 256 bytes and stores the settings and other information about the Xbox.

The Chihiro EEPROM key is <code>7B 35 A8 B7 27 ED 43 7A A0 BA FB 8F A4 38 61 80</code>

== Contents ==

{| class="wikitable"
! Offset !! Field !! Notes
|-
|}

== Notes ==

* [https://github.com/grimdoomer/PiPROM Read/Write an original Xbox EEPROM chip with a Raspberry Pi]