It is currently Tue Aug 14, 2018 4:27 am

All times are UTC - 7 hours



Forum rules


Related:



Post new topic Reply to topic  [ 8 posts ] 
Author Message
PostPosted: Mon May 28, 2018 10:20 am 
Offline

Joined: Fri Dec 02, 2016 12:08 pm
Posts: 7
Hey all, I'm looking to build a dev board for trying out various SA1 ROM hacks, and I was wondering if there were any boards that wouldn't work? I've looked at all of the different PCB types, and they all seem to have slightly different variations on each other. I just want to pick up the cheapest SA1 game to modify, but one that will be the most compatible. Also, my plan is to just install a socket in place of the old ROM chip, but just rewire the necessary pins, would that be the right method?


Top
 Profile  
 
PostPosted: Mon May 28, 2018 10:52 am 
Offline

Joined: Sun Apr 13, 2008 11:12 am
Posts: 7380
Location: Seattle
The only major differences between the different SA1 boards are the amount of RAM provided.

The PCB code tells you what any given board provides:
1L3B means
1 ROM
L SA-1
3 - battery-backed 8KiB SRAM (also seen: 0=none, 5=32KiB)
B - battery (also seen: N=no)
fifth digit: amount of not-battery-backed RAM
sixth digit: not-battery-backed RAM technology

Adding a socket is probably fine; the SA1 is fast compared to the rest of the SNES so avoid having a rat's nest of traces.


Top
 Profile  
 
PostPosted: Mon May 28, 2018 11:23 am 
Offline

Joined: Fri Dec 02, 2016 12:08 pm
Posts: 7
lidnariq wrote:
The only major differences between the different SA1 boards are the amount of RAM provided.

The PCB code tells you what any given board provides:
1L3B means
1 ROM
L SA-1
3 - battery-backed 8KiB SRAM (also seen: 0=none, 5=32KiB)
B - battery (also seen: N=no)
fifth digit: amount of not-battery-backed RAM
sixth digit: not-battery-backed RAM technology

Adding a socket is probably fine; the SA1 is fast compared to the rest of the SNES so avoid having a rat's nest of traces.


Awesome! I didn't know the PCB codes were identifiable in this way, this definitely helps thanks! And yeah, I agree a rat's nest of wires is undesirable, my plan is to only use wires for the few pins that need to be rerouted.


Top
 Profile  
 
PostPosted: Fri Jun 01, 2018 7:43 pm 
Offline

Joined: Sun Dec 02, 2012 8:17 am
Posts: 499
Location: East Texas
Really, what you'll ideally want is a 1L5B-xx where the "XX" is -11 or -12.... any number above -10. This is a 256k sram cart but can be easily expanded to 1mB sram.

Here is a dev. cart I made a while back. I upgraded the sram so it could test all games.
The rom, of course, is in a socket.

Oh, and I glued down the pcb so I wouldn't stress the adapter pins when changing roms out.


Attachments:
IMG_1859.JPG
IMG_1859.JPG [ 1.33 MiB | Viewed 2100 times ]
Top
 Profile  
 
PostPosted: Mon Jun 25, 2018 4:21 pm 
Offline

Joined: Sat Apr 07, 2018 7:39 pm
Posts: 7
I may be being a complete idiot here, but may I ask why you'd want a revision above -10? I thought all the boards have the same kind of stuff on them with the same code, and so revision wouldn't matter?

~Molive


Top
 Profile  
 
PostPosted: Mon Jun 25, 2018 4:38 pm 
Offline

Joined: Sun Apr 13, 2008 11:12 am
Posts: 7380
Location: Seattle
rev 02 only has enough lands for 32KB SRAM, while -10 and -11 have (resist-covered) lands supporting ... well, more SRAM. Could possibly be as much as would fit in a 32-pin package (=512KB)?


Top
 Profile  
 
PostPosted: Tue Jun 26, 2018 5:29 am 
Offline

Joined: Sun Dec 02, 2012 8:17 am
Posts: 499
Location: East Texas
Molive wrote:
I may be being a complete idiot here, but may I ask why you'd want a revision above -10? I thought all the boards have the same kind of stuff on them with the same code, and so revision wouldn't matter?

~Molive


The different revisions are hardware changes. Some SA1 games, albeit only a handful, need sram larger than 256k (64k ~1L3B~ being the most common and 256k ~1L5B~ next common) so if you are going to make a development/tester board, one would assume that you'd want a pcb capable of utilizing the higher sram sizes. The 1LxB-10 and higher have sram footprints where you can swap the sram to a larger kilobit size, whereas, the lower revisions don't. There are enough connected address lines (on the -10 and higher pcbs) from the SA1 to mount a 2mbit sram but the largest sram ever used in a SA1 game was 1mbit (1L8B-xx). The 1L8B came in revisions below and above the "-10" and interestingly enough, a 1L8B could have a 512k or a 1mbit sram (the distinction being the "8" as the sram size indicator for both sram sizes) depending on the game.

Of course, just acquiring a game that already is a 1L8B would be the easiest solution to make a development cart.


Top
 Profile  
 
PostPosted: Wed Aug 01, 2018 3:41 pm 
Offline

Joined: Sat Apr 07, 2018 7:39 pm
Posts: 7
Hey guys,
I've created a board which I can use for SA-1 dev. However, I've found that the Minipro programmer I'm using with an adapter is having trouble writing data to the 27c322 rom chips. Has anyone else had this problem before, or could anyone suggest why it's not working?
The chips read perfectly, but when trying to be written to there's an error on the first word and the program stops writing. I think it's that it thinks the data didn't save (it doesn't), but the error isn't described well in the message.

Thanks,
~Molive


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group