Boot process - Revision history

Unknown user at 06:38, 12 January 2020

2020-01-12T06:38:52Z

← Older revision		Revision as of 06:38, 12 January 2020
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	As a form of copy protection, the 1ST_READ.BIN file is generally scrambled according to an obfuscated formula, and the Dreamcast scramble loads this binary from disc it when loading 1ST_READ.BIN into memory. Loading an unscrambled binary ends up having the effect of scrambling the binary and destroying the program.<br>		As a form of copy protection, the 1ST_READ.BIN file is generally scrambled according to an obfuscated formula, and the Dreamcast scramble loads this binary from disc it when loading 1ST_READ.BIN into memory. Loading an unscrambled binary ends up having the effect of scrambling the binary and destroying the program.<br>
	<br>		<br>
	Using a file loader such as [[~~DCLOAD~~-IP]] or [[~~DCLOAD~~-~~SERIAL~~]] bypasses this entirely and allows enterprising developers to load programs directly onto the the console.<br>		Using a file loader such as [[dcload-ip]] or [[dcload-serial]] bypasses this entirely and allows enterprising developers to load programs directly onto the the console.<br>
	<br>		<br>
	Other details:		Other details:

Unknown user: Darc moved page Dreamcast Boot Process to Boot process

2020-01-10T05:43:17Z

Darc moved page Dreamcast Boot Process to Boot process

← Older revision

Revision as of 05:43, 10 January 2020

Unknown user at 02:02, 10 January 2020

2020-01-10T02:02:06Z

← Older revision		Revision as of 02:02, 10 January 2020
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	# IP.BIN jumps to 1ST_READ.BIN and excutes the loaded program		# IP.BIN jumps to 1ST_READ.BIN and excutes the loaded program
	<br>		<br>
	As a form of copy protection, the 1ST_READ.BIN file is generally scrambled according to an obfuscated formula, and the Dreamcast ~~unscrambles~~ it when loading 1ST_READ.BIN into memory. Loading an unscrambled binary ends up having the effect of scrambling the binary and destroying the program.<br>		As a form of copy protection, the 1ST_READ.BIN file is generally scrambled according to an obfuscated formula, and the Dreamcast scramble loads this binary from disc it when loading 1ST_READ.BIN into memory. Loading an unscrambled binary ends up having the effect of scrambling the binary and destroying the program.<br>
	<br>		<br>
	Using a file loader such as [[DCLOAD-IP]] or [[DCLOAD-SERIAL]] bypasses this entirely and allows enterprising developers to load programs directly onto the the console.<br>		Using a file loader such as [[DCLOAD-IP]] or [[DCLOAD-SERIAL]] bypasses this entirely and allows enterprising developers to load programs directly onto the the console.<br>

Unknown user at 00:05, 10 January 2020

2020-01-10T00:05:40Z

← Older revision		Revision as of 00:05, 10 January 2020
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	In general, the boot process is something like this:<br>		In general, the boot process is something like this:<br>
	# Dreamcast runs BootROM code and either lands at the BIOS page or tries reading a disc		# Dreamcast runs BootROM code and either lands at the BIOS page or tries reading a disc
	# IP.BIN is loaded to 0x8c008000		# [[IP.BIN]] is loaded to 0x8c008000
	# 1ST_READ.BIN (or whatever file is named directly in IP.BIN) is loaded to 0x8c010000		# 1ST_READ.BIN (or whatever file is named directly in IP.BIN) is loaded to 0x8c010000
	# SH4 jumps to IP.BIN's entry point and starts executing code		# SH4 jumps to IP.BIN's entry point and starts executing code
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	As a form of copy protection, the 1ST_READ.BIN file is generally scrambled according to an obfuscated formula, and the Dreamcast unscrambles it when loading 1ST_READ.BIN into memory. Loading an unscrambled binary ends up having the effect of scrambling the binary and destroying the program.<br>		As a form of copy protection, the 1ST_READ.BIN file is generally scrambled according to an obfuscated formula, and the Dreamcast unscrambles it when loading 1ST_READ.BIN into memory. Loading an unscrambled binary ends up having the effect of scrambling the binary and destroying the program.<br>
	<br>		<br>
	Using a file loader such as DCLOAD-IP or DCLOAD-SERIAL bypasses this entirely and allows enterprising developers to load programs directly onto the the console.<br>		Using a file loader such as [[DCLOAD-IP]] or [[DCLOAD-SERIAL]] bypasses this entirely and allows enterprising developers to load programs directly onto the the console.<br>
	<br>		<br>
	Other details:		Other details:

Unknown user at 00:03, 10 January 2020

2020-01-10T00:03:36Z

← Older revision		Revision as of 00:03, 10 January 2020
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	* 0x8c000000 is the base of the system's 16MB of RAM, accessed in privileged mode due to the SH4's 29-bit addressing method		* 0x8c000000 is the base of the system's 16MB of RAM, accessed in privileged mode due to the SH4's 29-bit addressing method
	* Dreamcast system calls and bios font are stored in the region 0x8c000000 - 0x8c004000		* Dreamcast system calls and bios font are stored in the region 0x8c000000 - 0x8c004000
	* The region 0x8c004000 - 0x8c008000 is used by multi-disc games to store persistent information across disc changes. This region is also used by persistent programs such as DCLOAD-IP/DCLOAD-SERIAL ~~such~~ that terminating programs can return to those loaders.		* The region 0x8c004000 - 0x8c008000 is used by multi-disc games to store persistent information across disc changes. This region is also used by persistent programs such as DCLOAD-IP/DCLOAD-SERIAL so that terminating programs can return to those loaders.
	* 0x8c008000 - 0x8c010000, which is used by IP.BIN, doesn't really matter beyond initial loading unless a program absolutely needs to refer to IP.BIN. The DCLOAD-IP/DCLOAD-SERIAL loaders overwrite most of IP.BIN after they've been loaded, for example, as they don't need any of it.		* 0x8c008000 - 0x8c010000, which is used by IP.BIN, doesn't really matter beyond initial loading unless a program absolutely needs to refer to IP.BIN. The DCLOAD-IP/DCLOAD-SERIAL loaders overwrite most of IP.BIN after they've been loaded, for example, as they don't need any of it.

Unknown user at 00:02, 10 January 2020

2020-01-10T00:02:49Z

← Older revision		Revision as of 00:02, 10 January 2020
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	In general, the boot process is something like this:<br>		In general, the boot process is something like this:<br>
	~~<br>~~
	# Dreamcast runs BootROM code and either lands at the BIOS page or tries reading a disc		# Dreamcast runs BootROM code and either lands at the BIOS page or tries reading a disc
	# IP.BIN is loaded to 0x8c008000		# IP.BIN is loaded to 0x8c008000

Unknown user: Created page with "In general, the boot process is something like this:

# Dreamcast runs BootROM code and either lands at the BIOS page or tries reading a disc # IP.BIN is loaded to 0x8..."

2020-01-10T00:02:15Z

Created page with "In general, the boot process is something like this: # Dreamcast runs BootROM code and either lands at the BIOS page or tries reading a disc # IP.BIN is loaded to 0x8..."

New page

In general, the boot process is something like this: 
 
# Dreamcast runs BootROM code and either lands at the BIOS page or tries reading a disc
# IP.BIN is loaded to 0x8c008000
# 1ST_READ.BIN (or whatever file is named directly in IP.BIN) is loaded to 0x8c010000
# SH4 jumps to IP.BIN's entry point and starts executing code
# IP.BIN jumps to 1ST_READ.BIN and excutes the loaded program
 
As a form of copy protection, the 1ST_READ.BIN file is generally scrambled according to an obfuscated formula, and the Dreamcast unscrambles it when loading 1ST_READ.BIN into memory. Loading an unscrambled binary ends up having the effect of scrambling the binary and destroying the program. 
 
Using a file loader such as DCLOAD-IP or DCLOAD-SERIAL bypasses this entirely and allows enterprising developers to load programs directly onto the the console. 
 
Other details:
* 0x8c000000 is the base of the system's 16MB of RAM, accessed in privileged mode due to the SH4's 29-bit addressing method
* Dreamcast system calls and bios font are stored in the region 0x8c000000 - 0x8c004000
* The region 0x8c004000 - 0x8c008000 is used by multi-disc games to store persistent information across disc changes. This region is also used by persistent programs such as DCLOAD-IP/DCLOAD-SERIAL such that terminating programs can return to those loaders.
* 0x8c008000 - 0x8c010000, which is used by IP.BIN, doesn't really matter beyond initial loading unless a program absolutely needs to refer to IP.BIN. The DCLOAD-IP/DCLOAD-SERIAL loaders overwrite most of IP.BIN after they've been loaded, for example, as they don't need any of it.