Famicom World

Family Computer => Technical & Repair Assistance => Topic started by: RC2C05-99 on April 28, 2012, 08:03:14 pm

Title: Looking for Famicom cart PCB compatible with NES-SCROM type
Post by: RC2C05-99 on April 28, 2012, 08:03:14 pm
I'm looking to convert a couple Famicom carts into Mechanized Attack and Sky Shark:

http://bootgod.dyndns.org:7777/profile.php?id=1218

The problem is, there appear to be no SCROM type boards used in Famicom carts.

I'm wondering if anyone knows a way to make a similar Famicom PCB type compatible with NES-SCROM?

It appears the only difference is the use of 64kb U1 PRG ROM.
Title: Re: Looking for Famicom cart PCB compatible with NES-SCROM type
Post by: 133MHz on April 28, 2012, 08:18:39 pm
It should work with plain SLROM if the only difference is a smaller PRG. :)
Title: Re: Looking for Famicom cart PCB compatible with NES-SCROM type
Post by: jpx72 on April 29, 2012, 08:32:25 am
Check this info:
http://wiki.nesdev.com/w/index.php/SXROM
Title: Re: Looking for Famicom cart PCB compatible with NES-SCROM type
Post by: RC2C05-99 on May 10, 2012, 05:30:13 am
I just tried swapping the Sky Shark ROMs into an SLROM board and unfortunately it didn't work (I had a spare onhand, so no biggie).

So, if the document above is correct, it looks like the only option would be to use an SL1ROM board.   There are only two documented FC carts that use it, but they appear to sell cheap enough.
http://bootgod.dyndns.org:7777/search.php?unif=HVC-SL1ROM

[EDIT]  Gah! Nevermind.  Had a closer look at SL1 (vs. SC), and it doesn't accept 32p on the Chr ROM slot.   Another roadblock...

Thanks for the input, guys.
Title: Re: Looking for Famicom cart PCB compatible with NES-SCROM type
Post by: jpx72 on May 10, 2012, 06:02:15 am
Mechanized attack has 28 pin PRG with 64kb and 32 pin CHR with 128kb. So if you find a HVC (famicom) SLROM board with the same specifications, it should work. BUT from my search is obvious that no HVC-SLROM  exists (in bootgod's database) that has only 128+64kb. All of them have 128+128kb.
http://bootgod.dyndns.org:7777/search.php?keywords=&pcb=HVC-SLROM&pcb_op=LIKE%20%60%@%%60&offset=0&field=32&order=asc
check http://nesdev.parodius.com/NES%20ROM%20Pinouts.txt (64kb PRG isn't even there)
check pins 20 and 22 on 32kb PRG and 128kb PRG. see the difference? Your 64kb rom (if it isn't a 128kb one with wasted space) has A0-A15. So trace pins 20 and 22 to see what they are on the original NES game.
...or it's something totally different, I don't know  :crazy:
Title: Re: Looking for Famicom cart PCB compatible with NES-SCROM type
Post by: famifan on May 10, 2012, 10:28:35 am
1) get any HVC-SLROM board :crazy:
2) enlarge PRG rom upto 128kb (64 + 64) :pow:
3) burn eproms :fire:
4) solder as usual 128kb ROMs 8)
5) play :bub:

i suppose that this schema is workable...