Does BIOS mod need bridge between R512 and 12v?

[darthcloud]

Hi,

I was wondering if the BIOS mod need the bridge between the R512 resistor and 12v like the region changer apps need.

I did the BIOS mod as show but it' doesn't work , DS intentify my flash chip correctly "DS_OK: Macronix flash detected, device id = c4"

Then it start erasing for a while, and after that. it try to write the first block and I got the following errors:
"DS_ERROR: Writing to flash timed out"
"DS_ERROR: Failed writing to flash at 00000001 (37 vs e3)"

My dreamcast don't have an 40pin TSOP flash like your, I have a 32pin TSOP (MB8581-70) instead but I connected the /WE line to pin 7 instead since it's the standard for flash of that size.

So I guess the problem is maybe the fact I don't have the R512 bridge.

If the bridge is not needed then I guess the problem is the /WE line..

Thanks

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[SWAT]

Hmm... It is difficult to say something about this...
Maybe you have 5 volt bios? These are hard to come, but maybe it is the case...
I think the problem with the WE line, I had something similar as you do when something I did not properly soldered.

[darthcloud]

Ok, so that bridge it not needed for the BIOS mod.

I'm going to check the supply voltage used by my BIOS.

I checked the continuity of all pin with my multimeter (Between base on pcb and top of the MX flash) and they are ok. I checked the WE line continuity too (From top of DC flash pin 7 to MX pin 44) and it's fine.

But if DS is able to identify the flash chip ID (Macronix id=c4) them the supply should be ok I guess.

Maybe I got the wrong pin for WE but I guess they used a Standard 128kb flash just like they used standard 256kb flash in later revision.

[darthcloud]

I just looked and and both the flash and bios is supply with 5v .

Thanks for the hint, I going to look for a 5v flash now!

Does DreamShell work will any 90ns flash chip or only with 29LV160?

[darthcloud]

Finaly got it to work!!

I switched MX chip supply from 5v to 3.3v and now it work, I was able to flash the bios

So it look like the DC bus can handle both 3.3v and 5v logic as '1'. And the MX chip can handle 5v as '1' too.

I bit hacky but it work.

Thanks for help.

EDIT: Did a shematic for older DC

[SWAT]

Congrats