2MB Support

psyko_chewbacca NA repo owner

This is something that will need some thought put into it.

At the moment, XBlast OS, when running on XBlast Hardware (XBlast Lite and Aladdin XBlast) assume a 1MB flash chip is used. BIOS bank config is hardcoded in that way and so is the code in the CPLD; 1 * 512KB and 1 * 256KB BIOS banks (and 1 * 256KB for the OS).

Next iterations of XBlast-compatible chips could have user configurable BIOS bank scheme, à la SmartXX, where you can specify bank size (256,512 or 1024KB) depending on your needs. For this to work, the CPLD code in the modchip must be implemented in such way the OS can push a dynamic BIOS bank configuration to the modchip's CPLD before jumping to a BIOS bank; to tell it the desired BIOS starts at offset X and ends at offset Y in flash. If it doesn't make much sense don't worry it does to me and to anyone with technical knowledge on how the Xbox reads of the BIOS from Flash/TSOP and into memory.

Point is, in XBlast OS, there need to be : 1. a mechanism to identify the total amount of flash space available for the user and locate the protected areas (XBlast OS flash space and maybe other areas)

save and retrieve bank configuration data in persisted XBlast OS settings (because it's XBlast OS that persists the info on how banks are split, not the modchip itself)
a way to dynamically display bank icons depending on user configuration. A configuration menu also needs to be there.
a communication protocol set up between XBlast OS and the CPLD on modchip so the OS can configure the modchip to make a predefined area in the flash available to the Xbox for it to load the BIOS from.

2018-05-18T15:14:45+00:00

Comments (2)

psyko_chewbacca NA repo owner
This is something that will need some thought put into it.

At the moment, XBlast OS, when running on XBlast Hardware (XBlast Lite and Aladdin XBlast) assume a 1MB flash chip is used. BIOS bank config is hardcoded in that way and so is the code in the CPLD; 1 * 512KB and 1 * 256KB BIOS banks (and 1 * 256KB for the OS).

Next iterations of XBlast-compatible chips could have user configurable BIOS bank scheme, à la SmartXX, where you can specify bank size (256,512 or 1024KB) depending on your needs. For this to work, the CPLD code in the modchip must be implemented in such way the OS can push a dynamic BIOS bank configuration to the modchip's CPLD before jumping to a BIOS bank; to tell it the desired BIOS starts at offset X and ends at offset Y in flash. If it doesn't make much sense don't worry it does to me and to anyone with technical knowledge on how the Xbox reads of the BIOS from Flash/TSOP and into memory.

Point is, in XBlast OS, there need to be : 1. a mechanism to identify the total amount of flash space available for the user and locate the protected areas (XBlast OS flash space and maybe other areas)
1. save and retrieve bank configuration data in persisted XBlast OS settings (because it's XBlast OS that persists the info on how banks are split, not the modchip itself)
2. a way to dynamically display bank icons depending on user configuration. A configuration menu also needs to be there.
3. a communication protocol set up between XBlast OS and the CPLD on modchip so the OS can configure the modchip to make a predefined area in the flash available to the Xbox for it to load the BIOS from.
- 2018-05-18T15:14:45+00:00
psyko_chewbacca NA repo owner
- changed status to on hold
This task will need to be picked back up when serious development on a new modchip will be made.

Development of protocol between OS and modchip will need to be defined conjointly between OS developer and CPLD developer.
- 2018-05-18T15:18:09+00:00
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