Viper Phase 1 Old/New Version Switchable Cartridge

The place for all discussion on gaming hardware
Post Reply
alamone
Posts: 719
Joined: Wed Mar 09, 2011 10:32 pm

Viper Phase 1 Old/New Version Switchable Cartridge

Post by alamone »

I made a switch to select Old/New version on Viper Phase 1.

Seibu1-4: 27C040 -> 27C801
Seibu5: 27C1024 -> 27C4096 (I did not have any 27C2048 handy)
Seibu6: 27C512 -> 27C010 (Need to tie pins 32 and 30 for VCC)

Youtube video:
https://t.co/iw26RjkAVW

Picture of mod:
https://twitter.com/alamone/status/1576 ... D9MM_zwX2g
User avatar
parodius
Posts: 720
Joined: Wed Jan 26, 2005 5:54 am
Location: Singapore

Re: Viper Phase 1 Old/New Version Switchable Cartridge

Post by parodius »

Oh, there’s no loading when you switch between the 2 versions?
Convenient indeed, I didn't remember that.
Last edited by parodius on Mon Oct 03, 2022 3:00 pm, edited 1 time in total.
My sales thread : 2020/07/20..MASTER.VER.
alamone
Posts: 719
Joined: Wed Mar 09, 2011 10:32 pm

Re: Viper Phase 1 Old/New Version Switchable Cartridge

Post by alamone »

Yes you can swap old/new version without reflashing the motherboard. I believe flashing is only for sound data and it's obviously the same data for old and new version.
PC Engine Fan X!
Posts: 8417
Joined: Wed Jan 26, 2005 10:32 pm

Re: Viper Phase 1 Old/New Version Switchable Cartridge

Post by PC Engine Fan X! »

Will this hardware hack work with the Seibu Kaihatsu SP1 cart of Viper Phase 1 U.S.A. version as well?

I know that VP1 USA is the same as the SP1 cart of VP1 "New Version".

PC Engine Fan X! ^_~
alamone
Posts: 719
Joined: Wed Mar 09, 2011 10:32 pm

Re: Viper Phase 1 Old/New Version Switchable Cartridge

Post by alamone »

I think it's possible to add the USA version if you wanted to, but you would have to change or bypass the region code byte check. I think also based on the motherboard's region, some game settings change (e.g. 2 loops or not), so it might operate differently even if the region code is modified. I'll have to get a spare SPI motherboard and do some tests.
alamone
Posts: 719
Joined: Wed Mar 09, 2011 10:32 pm

Re: Viper Phase 1 Old/New Version Switchable Cartridge

Post by alamone »

I think I might have misread your question.

If you are asking whether the hack itself is possible on a US region cart, the answer is yes - in fact this one was a US region cart, but it's working on my Japan SPI motherboard.
AFAIK the sub boards are all laid out the same but only the ROM contents is different. So you could use a VP1 JP old, VP1 JP new, or VP1 any region cart (which are based on new).
You just have to make sure the region byte is set correctly for your motherboard. Also, I'm not sure whether VP1 JP old on a non-Japan SPI motherboard works correctly.
Post Reply