Dev Bios on HKT-3000 Japanese Dreamcast?

[Marmotta]

I've got a bunch of MX29LV160TMC-90 chips and want to flash them with a dev bios. However, my Dreamcast is a HKT-3000 Ugo Denshi DC which either doesn't play CDRs at all or is extremely fussy about them, as I've never managed to get Dreamshell to boot on it. Also, it isn't indicated on the bottom of the console whether it's a VA0 or VA1.

Any ideas on how I can flash the bios chips without being able to boot Dreamshell?

[atreyu187]

Have you tried the modified version of DS for early Japanese models? I think only a BETA 4 variant is around but it will enable you to flash a BIOS none the less.

CDI format

[Bad_Ad84]

Pretty sure HKT-3000 is a VA0, which means the original bios is a 5v chip, not the 3.3v ones you have.

You can try wiring it up using a different source of VCC, but I have had trouble doing that on a few machines and ended up buying 5v chips which worked perfectly.

[atreyu187]

Yea Jinn did my va0 eith standard chips and it refused to work but he is having troubles even booting the Mil_CD to flash the BIOS chips. I know you have them pre-flashed maybe he could get one from you.

[Bad_Ad84]

All he has to do is ask and I will help him out. (which he should know)

[l_oliveira]

3V chips won't work properly on a VA0 unit (even if you power it correctly at 3.3v) because the HOLLY S1 bus is 5v on that ones. (GD drives are 5v with 3v compatibility built in)

[Bad_Ad84]

Well what it accepts as logic high fits a range (i.e. it doesnt need to be 5v completely) as I am sure you know. Its worked for some (including me) and doesnt on others.

Ive had a couple of VA0's work with the 3.3v method. However, the last few I have had didnt work (or were erratic). As I said, since then I dont even bother anymore and just fit the correct 5v chips.

[l_oliveira]

Just like there's the GD-ROM drive chips which work on any model of Dreamcast, there's 3.3v flash chips that are 5v tolerant. But yes, that's not aways the case, you know.