WildMage

So, I did some testing with my 1.0 with a single TSOP split switch (512k/512k), with Xblast.xbe. Xblast correctly identifies the TSOP chip, regardless of the switch is in the A position or the B position. However, when flashing, it will crash and freeze halfway through flashing the A position, or it will complete the flashing and reboot on the B position. Either way, it will flash the bios (mostly) correctly even if it freezes. I say mostly, because I then ran the latest BiosChecker XBE with CRC codes added for the various version Cerbios files I was testing, and it resulted in very strange results, some that showed obvious corruption. One of the switch positions showed 256k slot A as what was really in slot A, then position 2 as what was in slot B, then position 3 as what was in slot A, and position 4 as what was in slot B. The other switch position showed something like a correct slot 1, and correct slot 3 for what was flashed, but a CRC that didn't match anything flashed to it in slot 2 or slot 4. I was able to recover from a bad flash, by completely booting the system, and then completely loading Xblast, and THEN flipping the switch from the bank that worked, to the bank that wouldn't boot, and then flashing in Xblast. I had to do this, because some test BIOS'es I flashed just failed to boot at all. Due to this testing, I would go with what was pointed out by @KaosEngineer in the 2017 'TSOP splitting' thread, that explained "Why you shouldn't do TSOP Splitting": https://web.archive.org/web/20070205091445/http://www.xbox-linux.org/wiki/Why_you_shouldn%27t_do_TSOP_Splitting After running on the split bios on an old, fairly beat up system, I attempted to use XCAT 1.0 to archive what was on a few different pulled HDD's, and after running for sometimes hours, it would eventually just crash and completely shut down long before the archiving was complete. The crashing might be unrelated, due to the console being beat as hell, but the results of the BiosChecker were very odd and disconcerting either way, and the article linked above does kind of explain the dangers of attempting to split a bios, and how it's honestly not really worth it, if stability is important to you.

Yeah, I didn't think about this, but an XBlastOS bios would be pretty pointless for a split TSOP, unless it was on the first and therefore ungrounded bank, wouldn't it? I've only ever had luck flashing the entire ungrounded TSOP at once. If any switch is hit, the flash program just couldn't even see the TSOP, although I admit I've never messed with anything but the Xblast xbe, and standard gaming bios files. I used my switched 1.0 bios to have one VGA bios, and an almost identical bios that was not VGA, and maybe another bank to switch to a different OS, like one that boots into Avalaunch instead of XBMC. It was all done pretty much because I could though, and it never saw much real world use.

So, basically, when a part of a TSOP bank is grounded, the Xbox can't see that part of the chip anymore. By grounding specific parts of the chip away like that, the Xbox will skip over those parts and boot the first bios file it sees. So to accomplish what your shooting for, you want to build your custom 1024k bios file that contains all four banks, by just simply combining all the 256k files together into a single large file. This is easy to do from a DOS or Linux command prompt. In DOS you use something like 'copy biosA.bin + biosB.bin + biosC.bin + biosD.bin bigbios.bin'. Then you take the 1024k bios file and flash it to your TSOP with no switches active, so the chip is ungrounded and you have access to the entire 1024k. Then you would use your switches to access the specific bank you want to load from. That's how I've always done it at least.

I recently opened my launch Xbox 1.0... and man, it was a huge mess in there, from all the mods I tried to do to it back in the late 00's. I put in an Xirc2, added a network and HDD activity LED drilled through the sides of the front of the case, split the TSOP with a external switch, put a remote receiver IR into it internally, and added a 4PDT switch so it's on controller port 4, until you plug in a controller. But I did this back in the mid 2000's, with a $15 radio shack soldiering iron and barely any skill. There's hot glue on the motherboard to hold the wires down (cringe), the wires I used are all too big it or too small gauge, cold soldier joints, etc. The console boots, but then crashes during the intro animation. I remember that after I added one mod too many, it stopped working, back in the day, and I just tossed it in a corner. The case didn't even push down properly because of all the wires, and I remember if I didn't push it down tight, it would boot longer before crashing, haha. When I have some time I'm gonna try to restore it, although mostly for sentimental reasons and not because I'll ever want it to be a daily driver again.