It is currently Tue Oct 17, 2017 11:55 am

All times are UTC - 7 hours





Post new topic Reply to topic  [ 9 posts ] 
Author Message
 Post subject: N64 EEPROM / SRAM info?
PostPosted: Sat Dec 19, 2015 2:42 pm 
Offline
User avatar

Joined: Tue Dec 04, 2012 3:28 pm
Posts: 337
Location: Canada
Is there any chips that are compatible with the N64 Gamepak 4K/16K EEPROMs? They seem to use only 1 data line S_DAT (doesn't specify in or out), a clock, and /reset... but most other serial eeproms have a CS, CLOCK, and a data in and out.

And the same question is posed for the SRAM they used in games like Zelda. I'm assuming that they had some kind of latching built into the SRAM similar to the ROM to work with the multiplexed addresses, but there doesn't appear to be a pinout anywhere for that chip LH52V246A.


EDIT: Just thinking...what if some kind of AND gate was used to combine the D_IN and D_OUT on a serial EEPROM to the S_DAT pin? Would that work for a read/write function? Also, could CS be tied to /RESET on the console with an inverter to control the chip enable? If those worked, then perhaps a replacement could be possible.


Top
 Profile  
 
PostPosted: Sat Dec 19, 2015 4:53 pm 
Online

Joined: Sun Apr 13, 2008 11:12 am
Posts: 6274
Location: Seattle
If I had to guess, I'd guess it's shaped like I²C...


Top
 Profile  
 
PostPosted: Sat Dec 19, 2015 6:59 pm 
Offline

Joined: Mon Apr 01, 2013 11:17 pm
Posts: 437
getafixx wrote:
Is there any chips that are compatible with the N64 Gamepak 4K/16K EEPROMs?
These seem to be custom parts manufactured specifically for Nintendo, so it's unlikely that there are any drop-in replacements. You might be able to get away with some other EEPROM, if you can find any that speak the same protocol, but I can't guarantee that would be enough to fool the games with copy protection.

getafixx wrote:
And the same question is posed for the SRAM they used in games like Zelda.
This is a custom part. It combines a standard SRAM with the bus interface logic to reduce pin count.


Top
 Profile  
 
PostPosted: Sat Dec 19, 2015 10:05 pm 
Offline
User avatar

Joined: Tue Dec 04, 2012 3:28 pm
Posts: 337
Location: Canada
Joe wrote:
These seem to be custom parts manufactured specifically for Nintendo, so it's unlikely that there are any drop-in replacements. You might be able to get away with some other EEPROM, if you can find any that speak the same protocol, but I can't guarantee that would be enough to fool the games with copy protection.

Yeah, I know that some games use the CIC as a means of copy protection so that a cart with a different CIC than the game was expecting won't work. I'm not sure that the EEPROMs were used in the same manner, but I figure they'd have to be able to be written and read from the same way... Probably not easy.

Joe wrote:
This is a custom part. It combines a standard SRAM with the bus interface logic to reduce pin count.

That's pretty much it, but does anyone have the pinout for them? There seems to be almost no information, other than it appears to use the same multiplexing technique that the Maskrom used for address and data lines. I'd pop open my Zelda and tone out each line, but i'm afraid that will more than likely erase my saved games (my original record when I bought the game!)


Top
 Profile  
 
PostPosted: Sun Dec 20, 2015 7:08 am 
Offline

Joined: Mon Apr 01, 2013 11:17 pm
Posts: 437
getafixx wrote:
Yeah, I know that some games use the CIC as a means of copy protection so that a cart with a different CIC than the game was expecting won't work. I'm not sure that the EEPROMs were used in the same manner, but I figure they'd have to be able to be written and read from the same way... Probably not easy.
A handful of games check for different save types, and if they detect the wrong one, activate copy protection. I don't know exactly how this works, so I couldn't tell you if it relies on the EEPROM being an exact match or only checks the capacity of the EEPROM.

getafixx wrote:
That's pretty much it, but does anyone have the pinout for them? There seems to be almost no information, other than it appears to use the same multiplexing technique that the Maskrom used for address and data lines. I'd pop open my Zelda and tone out each line, but i'm afraid that will more than likely erase my saved games (my original record when I bought the game!)
If you aren't trying to replace one, then what good is the pinout? No compatible chips exist.

In any case, the pinout is nearly identical to the mask ROM. The only differences I see are that pins 7 and 22 don't seem to be connected to anything, and pin 8 is used to enable the chip while the console is on (and reduce power consumption while running on the battery).

Code:
N64 mask ROM pinout
       __ __
      |  V  |
AD0 --|     |-- AD15
AD1 --|     |-- AD14
AD2 --|     |-- AD13
AD3 --|     |-- AD12
VCC --|     |-- GND
AL  --|     |-- GND
/R  --|<   >|-- VCC
GND --|<    |-- /W
AH  --|     |-- /R
GND --|     |-- VCC
AD4 --|     |-- AD11
AD5 --|     |-- AD10
AD6 --|     |-- AD9
AD7 --|     |-- AD8
      |_____|
Code:
N64 SRAM pinout
       __ __
      |  V  |
AD0 --|     |-- AD15
AD1 --|     |-- AD14
AD2 --|     |-- AD13
AD3 --|     |-- AD12
VCC --|     |-- GND
AL  --|     |-- GND
N/C --|<   >|-- N/C
EN  --|<    |-- /W
AH  --|     |-- /R
GND --|     |-- VCC
AD4 --|     |-- AD11
AD5 --|     |-- AD10
AD6 --|     |-- AD9
AD7 --|     |-- AD8
      |_____|


Top
 Profile  
 
PostPosted: Mon Dec 21, 2015 9:15 am 
Offline
User avatar

Joined: Tue Dec 04, 2012 3:28 pm
Posts: 337
Location: Canada
Thanks for the info!

I was mainly just looking for something to tinker with during my Christmas holidays as I've got some time off of work. Wanted to see if I could increase the size of the EEPROM or the SRAM in a game without it causing issues.

Been looking at NAND memory, and seems to have all the right pins for matching up to a Maskrom pinout. Is that what their Maskroms were using? They seem to have the same address latching function, with an ALE pin to control it (though, the Maskrom has a seperate ALE for high and low access). Something like this: http://www.spansion.com/Support/Datasheets/S34ML01G2_04G2.pdf


Top
 Profile  
 
PostPosted: Mon Dec 21, 2015 9:19 am 
Offline
User avatar

Joined: Tue Dec 04, 2012 3:28 pm
Posts: 337
Location: Canada
lidnariq wrote:
If I had to guess, I'd guess it's shaped like I²C...


And you're right, seems to be the closest thing to what they used.


Top
 Profile  
 
PostPosted: Mon Dec 21, 2015 2:11 pm 
Offline

Joined: Mon Apr 01, 2013 11:17 pm
Posts: 437
getafixx wrote:
Been looking at NAND memory, and seems to have all the right pins for matching up to a Maskrom pinout.

Won't work, though. The protocol those chips use isn't compatible with the N64.


Top
 Profile  
 
PostPosted: Mon Dec 21, 2015 7:40 pm 
Offline
User avatar

Joined: Tue Dec 04, 2012 3:28 pm
Posts: 337
Location: Canada
Figures. Well thanks for the help anyways!


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 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