$ cat dreamcast-black-swirl.txt
Black Swirl of Death

One system (VA1) presents this issue and cannot boot any media.
This systems was an attempted region change that failed immediately on first boot
The Region change method puts 12V to the R512 resistor making the read only portion of the flashrom writable. This should be fine in most cases for a short time (more than enough time to change the region) then remove the 12V wire and/or install a switch. The read only area of flashrom holds the region data for the console.
A Black swirl means the flashrom region code has become corrupted, in some cases this can mean it still maintains a region code in the flashrom and can only boot certain discs as a result. The other more serious version is the region code has been wiped (or so the thought is) and the system can no longer boot any media.

Repair

The main repair for this issue is to replace the flashrom

Proposal

An alternate proposal I believe could be to use an 4wire mod chip (providing one can be found) to boot and reflash the flashrom with a good code.


The 4wire modchip cycles through region codes to match the disc to boot region free, this ignores the flashrom and with the flashrom in writable mode I should be able to boot the region changer and flash the device restoring functionality.
Modchip Sellers

* Zero found active
* DC 5wire Modchip Install - No longer selling
* DC 4-wire Region Chip Install - No longer selling

BIOS replacement

* Custom BIOS goes to version 1.031!
* Dreamcast Dev Bios (Region Free Too!)
* Dreamcast Modding Service
* Dreamcast Bios Mod
* retrogamerstuff.com
* BIOS and 1950 fix booting discs on Black Swirl
* Black Swirl of Death on August 1999 One Wire Modded Dreamcast, how do I fix this?


Alternatives

* Boot loop fix - Set system date to 01/01/1950 to stop the boot look once black swirl is active, this does not fix game booting
* Region Free Bios Replacement - Seems to work around it. you can also boot dc-swat in combination with the 1950 fix so i assume you could rewrite the flashrom by doing the 12V mod again in concert with these mods.


References

* Dreamcast System Calls - https://mc.pp.se/dc/syscalls.html
* Dreamcast Black Swirl of Death - https://web.archive.org/web/20190403053845/https://assemblergames.com/threads/dreamcast-black-swirl-of-death.54096/
* Dreamcast Region Mod Chip - Racketboy - https://www.racketboy.com/forum/viewtopic.php?t=34840
* Dreamcast Bios Hack - http://blog.jacksoftlabs.com/dreamcast-bios-hack/
* Dreamcast 4 Wire Modchip Install - http://www.mmmonkey.co.uk/dreamcast-4-wire-mod-chip-install/
* Help - Region Changer Error (Is my DC Fucked up now?) - https://web.archive.org/web/20141104150354/https://assemblergames.com/forums/showthread.php?22999-Help-Region-Changer-Error-%28Is-my-DC-Fucked-up-now-%29
* Or, how I took apart my Dreamcast and did even more ghastly things to it than drw did to his =)
* Dreamcast Modchip & Bios replacement thread - http://cadcdev.sourceforge.net/hdwrprj/navi/
* dreamcast.wiki - https://dreamcast.wiki/Dreamcast.wiki
* dc-virtcd - https://github.com/zeldin/dc-virtcd
* bITmASTER´s dCdeV - https://web.archive.org/web/20030416002947/http://homepages.compuserve.de/bITmASTER32/dc-index.html
* Where can I buy a 4 wire region free mod chip at? - https://www.reddit.com/r/dreamcast/comments/4nxnxg/where_can_i_buy_a_4_wire_region_free_mod_chip_at/
* Dreamcast 4 wire modchip - Safe? - http://www.neo-geo.com/forums/showthread.php?242792-Dreamcast-4-wire-modchip-Safe
* is it still possible to find the 4wire mod chips? - https://dreamcast-talk.com/forum/viewtopic.php?t=3059
* Where to buy latest Dreamcast Modchip? (and other Dreamcast mod/repair questions) - https://bordersdown.net/threads/85330-Where-to-buy-latest-Dreamcast-Modchip-(and-other-Dreamcast-mod-repair-questions)
* dreamcast import mod? - https://nfggames.com/forum2/index.php?topic=853.0
* Modking - http://www.angelfire.com/super/modking/
* Dreamcast self kit installation mod chip - https://www.cdrinfo.com/d7/content/dreamcast-self-kit-installation-mod-chip
* dc-swat.ru - http://www.dc-swat.ru/
* DCGAGA - https://dreamcastgaga.blogspot.com/
* DC Patches - http://yagonawa.free.fr/DC/