Unibios for SVC Chaos PCB Version first try

[chacal231077]

Hi!


I did a first test, as Razoola had suggested to me at the time, to copy the bios 4 times for this version of PCB.

I did a clean job, but it didn't work.

Any suggestions for trying again?

I will order a SOP44 SMD socket connector so as not to damage the PCB

I programmed an MX26l6420MC-90 for the 4x bios.

Do you have an idea

Thank you

 

[ekorz]

Is that a 3.3v chip in a 5v circuit?

 

[stj]

maybe you need to byteswap the data
can you dump the original ?

 

[chacal231077]

No I have a wellon VP598 it does not support this type of chip

For the unibios chip to install on it I went through buyicnow.com

I found this on NeoGeo neo-geo.com

NBM + Universe BIOS + SVC Chaos PCB

 

[ack]

That chip you used looks to be 64Mbit. The stock bios/unibios are 1Mbit, so you would needed to do 64x copies. You were likely told to use 4x copies because the bios chip on that pcb is 4mbit per mame and they assumed you would use the same size chip.

 

[chacal231077]

Ah Shit the code has to swim alone in a 64Mbit olympic pool lol

An SMS 44 SOP chip reference closer to the capacity of the bios to offer ?

Thank You

 

[stj]

maybe i can help, what's the original chip number?

 

[stj]

looking at mame, you need a 29f400
i have those somewhere.
you may even be able to use a 29f100 - i'd have to compare the pinout

 

[chacal231077]

maybe i can help, what's the original chip number?

No Number just SP - 4X

AM29F100B-90SC Datasheet Maybe ?

 

[ack]

You might consider sticking with a 4mbit chip. Check this comment in mame

https://github.com/mamedev/mame/blob/master/src/mame/drivers/neopcb.cpp#L217

Sound like you could have both unibios and a stock bios on the chip then use hard dip3 to swap between them.

 

[stj]

checking the pads & tracks for flash that a rom wont need:

1 - not connected
2 - not connected
3 - ground (A17)
33 - connected to somewhere.
43 - not connected (/W)
44 - not connected (/RP)

so if A17 is grounded you can only use 256k - a 29f200
you must connect 43 and probably 44 to the 5v rail - preferably through 10k resistors

 

[ack]

checking the pads & tracks for flash that a rom wont need:

1 - not connected
2 - not connected
3 - ground (A17)
33 - connected to somewhere.
43 - not connected (/W)
44 - not connected (/RP)

so if A17 is grounded you can only use 256k - a 29f200
you must connect 43 and probably 44 to the 5v rail - preferably through 10k resistors

I got a couple 29F200 today and your suggestion works as expected, thanks. I tied 43/44 via the 10k to pin 33 (BYTE) which the board already connects to Vcc to force 16 bit data mode.

I used

cat uni-bios.rom sp1-u4.bin > bios.bin

and can confirm that dip3 lets you switch between them.