Forum: Hardware Mods

on 2008/07/24 11:57 CEST, by mmmonkey posts: 2 1 stars

Hi

I'm new around here, I found this site whilst searching for more info about the MultiBIOS and then found that it's been released to download - thanks Arakon :)

This has renewed my interest in buying a MegaCD1 again, I'm sure I read somwhere that it would be possible to intall a MultiBIOS with a single 3 position on-off-on switch (although you wouldn't be able to select the Columns game but that's okay), so I sat down with the tutorial and a scrap of paper and tried to get it straight in my head.

I can't for the life of me figure it out though, I spent ages trying to sort it out but to be honest I don't really understand enough about it.

Any advice would be appreciated, is it possible - and if so, how? I don't have any blank chips to flash yet so can't try it out for real, it's all just theory at the moment.

Many thanks
Pete

on 2008/07/27 12:31 CEST, by Arakon posts: 23 3 stars

Quote:

Hi

I'm new around here, I found this site whilst searching for more info about the MultiBIOS and then found that it's been released to download - thanks Arakon :)

This has renewed my interest in buying a MegaCD1 again, I'm sure I read somwhere that it would be possible to intall a MultiBIOS with a single 3 position on-off-on switch (although you wouldn't be able to select the Columns game but that's okay), so I sat down with the tutorial and a scrap of paper and tried to get it straight in my head.

I can't for the life of me figure it out though, I spent ages trying to sort it out but to be honest I don't really understand enough about it.

Any advice would be appreciated, is it possible - and if so, how? I don't have any blank chips to flash yet so can't try it out for real, it's all just theory at the moment.

Many thanks
Pete

It should be doable with a 3-position flip switch. connect 5V to the center pin, top and bottom pin to the two address pins on the eprom. that way you should be able to switch between 3 banks, although center position would leave the pins floating, not grounded, but in my experience that should work fine either way.

edit: although you may have to shuffle the bios order around.. i.e. split the file up into 4 128 kb pieces and put them back together in a different order.. otherwise you might end up with 2 bioses and columns instead of the 3 bioses and ignoring columns.

on 2008/08/09 16:41 CEST, by mmmonkey posts: 2 1 stars

Cheers for the reply, I'll give it a go when the right price CD unit shows up!

Pete

on 2008/10/04 21:07 CEST, by GhostWolf posts: 12 3 stars

You might want to add two pull-down resistors at 10Kohm each. (Usual there is pull-up resistors in circuits but here pull-down is needed.) At the bottom of this page (external link)

they make a single switch option.

edit:
Oh... look that was your site mmmonkey... :)
Ghost Wolf feels rather stupid...

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