Format:SNA snapshot file format - Revision history

ColinPitrat at 15:30, 9 March 2025

2025-03-09T15:30:17Z

← Older revision		Revision as of 15:30, 9 March 2025
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	* The snapshot format doesn't support additional hardware. A basic CPC464, CPC664, CPC6128 system is assumed.		* The snapshot format doesn't support additional hardware. A basic CPC464, CPC664, CPC6128 system is assumed.
	* The snapshot format doesn't support KC Compact or Aleste hardware.		* The snapshot format doesn't support KC Compact or Aleste hardware.
	* The snapshot doesn't have knowledge of which ROMs are in use. This means it doesn't know which OS, BASIC or AMSDOS ROM, and nothing about expansion roms.		* The snapshot doesn't have knowledge of which ROMs are in use. This means it doesn't know which OS, BASIC or AMSDOS ROM, and nothing about expansion roms. On Plus range, it doesn't know which Cartridge is loaded.

	The format generally assumes a base CPC6128/6128Plus system with no attached hardware except for up to 512K of dk'tronics compatible RAM.		The format generally assumes a base CPC6128/6128Plus system with no attached hardware except for up to 512K of dk'tronics compatible RAM.

Lordheavy: cleanup example of RLE compression

2022-08-07T10:00:30Z

cleanup example of RLE compression

← Older revision		Revision as of 10:00, 7 August 2022
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	i.e. <control byte>, <count>, <byte>		i.e. <control byte>, <count>, <byte>

	Examples:		Examples (Uncompressed = Compressed):
			* 11 22 33 = 11 22 33
	Uncompressed = Compressed		* E5 03 11 = 11 11 11
	11 22 33 = 11 22 33		* E5 00 = E5
	E5 03 11 = 11 11 11
	E5 00 = E5

	=== Breakpoint chunk (Winape emulator specific) ===		=== Breakpoint chunk (Winape emulator specific) ===

Arnoldemu: /* Memory */

2014-08-23T14:15:12Z

Memory

@@ Line 687: / Line 687: @@
 E5 03 11 = 11 11 11
 E5 00 = E5
 == Memory ==

Arnoldemu: /* Memory block chunks (CPC/Plus/KC Compact/Aleste) */

2014-08-21T08:29:44Z

Memory block chunks (CPC/Plus/KC Compact/Aleste)

← Older revision		Revision as of 08:29, 21 August 2014
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	\|}		\|}

	== Memory block chunks (CPC/Plus/KC Compact/Aleste) ==		=== Memory block chunks (CPC/Plus/KC Compact/Aleste) ===

	There may be 1 or more of these memory blocks.		There may be 1 or more of these memory blocks.

Arnoldemu: /* Limitations of this snapshot format */

2014-08-21T08:29:20Z

Limitations of this snapshot format

← Older revision		Revision as of 08:29, 21 August 2014
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	* The snapshot format doesn't support KC Compact or Aleste hardware.		* The snapshot format doesn't support KC Compact or Aleste hardware.
	* The snapshot doesn't have knowledge of which ROMs are in use. This means it doesn't know which OS, BASIC or AMSDOS ROM, and nothing about expansion roms.		* The snapshot doesn't have knowledge of which ROMs are in use. This means it doesn't know which OS, BASIC or AMSDOS ROM, and nothing about expansion roms.
	It generally assumes a CPC6128/6128Plus system with ~~ram expanded~~ up to 512K.
			The format generally assumes a base CPC6128/6128Plus system with no attached hardware except for up to 512K of dk'tronics compatible RAM.

Arnoldemu: /* CPC+ Chunk */

2014-08-21T08:28:09Z

CPC+ Chunk

← Older revision		Revision as of 08:28, 21 August 2014
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	== V3 Chunks ==		== V3 Chunks ==

	=== CPC+ Chunk ===		=== CPC+ Chunk (Plus only) ===

	Chunk name: "CPC+"		Chunk name: "CPC+"

Arnoldemu: /* Memory block chunks */

2014-08-21T08:27:54Z

Memory block chunks

← Older revision		Revision as of 08:27, 21 August 2014
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	\|}		\|}

	== Memory block chunks ==		== Memory block chunks (CPC/Plus/KC Compact/Aleste) ==

	There may be 1 or more of these memory blocks.		There may be 1 or more of these memory blocks.

Arnoldemu: /* Memory */

2014-08-21T08:27:26Z

Memory

← Older revision		Revision as of 08:27, 21 August 2014
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	== Memory ==		== Memory ==

	Uncompressed snapshot allows sizes of:		Uncompressed memory described by the snapshot allows sizes of:
	* 64K (base 64K only),		* 64K (base 64K only),
	* 128K (base 64K + 64K dk'tronics compatible RAM expansion using ram selections C4-C7),		* 128K (base 64K + 64K dk'tronics compatible RAM expansion using ram selections C4-C7),

Arnoldemu: /* Memory block chunks */

2014-08-21T08:26:50Z

Memory block chunks

← Older revision		Revision as of 08:26, 21 August 2014
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	== Memory block chunks ==		== Memory block chunks ==

	~~Chunk name: MEM0..MEM8. 64K is stored per block~~.		There may be 1 or more of these memory blocks.

	MEM0 ~~for Standard 64k~~.		Chunk name: MEM0..MEM8.
	~~MEM1 to~~ MEM8 ~~for memory expansion bank~~.

	~~If a chunk exists for that~~ block~~, this means the memory is stored compressed~~.		Each block represents 64K.

	It is possible to have a snapshot with 64KB base ram uncompressed and additional banks compressed, but it's advised to either use MEM chunks or store the memory uncompressed in the V2 style.		MEM0 describes the standard on-board 64k.
			MEM1...MEM8 for memory expansion bank.
			The MEM1..MEM8 memory blocks map to RAM expansions:
			* MEM1 = extra 64KB ram in CPC6128 or 6128Plus
			* MEM1-4 = 256KB dk'tronics compatible ram expansion
			* MEM5-8 = 256KB dk'tronics silicon disk compatible

			Other RAM expansions have the full 512KB such as the X-MEM. These map to MEM1-MEM8.


			If a chunk exists in the snapshot that means that memory is stored compressed.

			It is possible to have a snapshot with 64KB base ram uncompressed and additional banks compressed but it's advised to either use MEM chunks or store the memory uncompressed in the V2 style.

			The memory size in the snapshot refers to the amount of uncompressed V2 style memory that is in the snapshot. If the memory is described only by chunks it is 0.
			If there is both uncompressed and compressed data then the compressed data takes priority over the uncompressed data. I.e. handle the uncompressed data first then the compressed data.

	A RLE compression is used with 0x0e5 as the control byte.		A RLE compression is used with 0x0e5 as the control byte.

	~~Example~~:		i.e. <control byte>, <count>, <byte>

			Examples:

			Uncompressed = Compressed
	11 22 33 = 11 22 33		11 22 33 = 11 22 33
	E5 03 11 = 11 11 11		E5 03 11 = 11 11 11

Arnoldemu: /* CPC+ Chunk */

2014-08-21T08:15:38Z

CPC+ Chunk

← Older revision		Revision as of 08:15, 21 August 2014
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	The following chunks are currently defined:		The following chunks are currently defined:

			== V3 Chunks ==

	=== CPC+ Chunk ===		=== CPC+ Chunk ===

	Chunk name: "CPC+"		Chunk name: "CPC+"

			If this chunk exists assume that you should use a 464Plus/6128Plus configuration to run the snapshot.

	Chunk data:		Chunk data: