another question on Free Region Bios Mod.

Hi, many articles mention a "byteSwapping", before flashing the eprom ... what do you mean? I do use Flowrebuilder and quiet?
Someone kindly, I would like byteswappare rom bios free region of the saturn properly.
Obviously everything in due time I have no hurry, though some informazionein more does not hurt.
thanks

 

It means that the files floating around are in Little Endian format and if you decide to flash them in an actual EEPROM to use on an actual Saturn you need to byteswap their content and make the files Big Endian prior to flashing them [it is possible that your flashing sw allows to do the conversion at load time, not sure]

In more details the files floating around although contain valid 16 bits data are stored as:
LoByteOf16BitWord0,
HiByteOf16BitWord0,
LowByteOf16BitWord1
HiByteOf16BitWord1
...

What the Saturn expects in the EEPROM (which are 16bits by the way) is instead:

HiByteOf16BitWord0
LoByteOf16BitWord0
HiByteOf16BitWord1
LowByteOf16BitWord1
....

So you see the order of the bytes is swapped. The files are in Little Endian as that is the std format on x86, while the SH-2 processors of the Saturn are Big Endian.

More info here:
http://www.scadacore.com/community-support/blogs/software-programming/174-the-trouble-with-endians

It is possible that there are already byteswapped files floating around, I just don't know.
Usually the ones I found are not.

A way to do it in linux is via
dd if=yourinputfile of=youroutputfile conv=swab
[swab with a b]

It also works in windows if you care to install cygwin.

There are for sure tools that allow you to do it with fancy UIs I just don't know of any on top of my head, when I needed it I learnt to use 'dd swab'.

 

ok, thank you very much, I understood a lot more ', although they are far from understanding what really do, but I think it's inexperience.
For now I've found who I program an EPROM, memomale (expletive) ... but in his time buying a programmer myself and I have to sbrigare..magari looks more 'simple than necessary. As ll'hex 12c508a for the ps1

 

To byteswap means swap the high/even byte ( upper 8 bits from D8 to D15) with low/odd byte (lower 8 bits from D0 to D7).Evey programmer software has this function.

 

Here is a collection of the Bios files bytes wapped and padded to 1mb and all region free, you can thank Bad_Ad for this collection.

http://www.mediafire.com/download/ty448rvh3vz1ps5/swapped_1mb_RF_Bios.zip

Just load it up and write to the chip.

 

Ok thanks, aid, I solved the mystery ... there are programs apposta..e then I need a programmer EPROM, which supports the chip to flash
thanks