SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Discussion of hardware and software development for Super NES and Super Famicom. See the SNESdev wiki for more information.

Moderator: Moderators

Forum rules
  • For making cartridges of your Super NES games, see Reproduction.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Kayumba »

calima wrote: Wed Nov 09, 2022 9:24 am Heat-sensitive?
How by removing FM18W08 from the PCB it can be "Heat" ?
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by lidnariq »

How did you remove the FeRAM from the PCB?
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Kayumba »

lidnariq wrote: Wed Nov 09, 2022 12:14 pm How did you remove the FeRAM from the PCB?
With my hand :D
I use pins sockets to plug into my usually SRAM emplacement.
My adapter look like this one:
Image
I've done two removing just to confirm.
Maybe my fingers do some short circuit ?
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by lidnariq »

Theoretically FeRAM should not lose its contents randomly - I have no idea what's going wrong. Maybe you're triggering a spurious write somehow (no idea how) and then the game detects invalid data...
Markfrizb
Posts: 607
Joined: Sun Dec 02, 2012 8:17 am
Location: East Texas

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Markfrizb »

If you are testing 64k sram saves —- the FM18w08 is a 256k device. Do you have the extra address lines connected? A13/14?
Or floating? Maybe you need some capacitor to power the Fram at power down to give it time to store the data?
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Kayumba »

Markfrizb wrote: Wed Nov 09, 2022 9:26 pm If you are testing 64k sram saves —- the FM18w08 is a 256k device. Do you have the extra address lines connected? A13/14?
Or floating? Maybe you need some capacitor to power the Fram at power down to give it time to store the data?
I made jumpers to do configuration of my FM18w08 (256k) as FM16w08 (64k) and 16k.
So when I do setup for 64k here is my config :
pin 1 (A14) = GND (NC FM16w08)
pin 26 (A13) = GND (NC FM16w08)

Image

FM16w08 (64k) use as 16k
Image

I've done test only with 64k and it work's (save/load/erase).
Only when I takeoff feram that file are lost.

Should do more tests to see what happened with other configurations 256k and 16k.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Kayumba »

I've done some more tests.
I was wrong.
  • Load saved file after that cartridge was removed for 10min : file lost
Saved file are despaired also when the cartridge are removed.
In my first test I done "remove/insert" to quickly and cause of capacitor on my PCB the volage was still present.
Markfrizb
Posts: 607
Joined: Sun Dec 02, 2012 8:17 am
Location: East Texas

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Markfrizb »

Maybe you should try programming the Fram with your eprom programmer? Find a 27cxxx eprom that is the same memory size as the 256k ram that your programmer supports….. load some data into it. See if it retains.
I’ve done this myself so I know this can work.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Kayumba »

Markfrizb wrote: Sat Nov 12, 2022 10:02 pm Maybe you should try programming the Fram with your eprom programmer? Find a 27cxxx eprom that is the same memory size as the 256k ram that your programmer supports….. load some data into it. See if it retains.
I’ve done this myself so I know this can work.
Thank's for idea Markfrizb.
I will try to do it next week.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Kayumba »

I done some voltage test when PCB are inserted:

Feram: /CE (pin 20) = 4.46v
Feram: /OE (pin 22) = 2.36v
Feram: /WE (pin 27) = 4.80v

74HC02D: 2B (pin 6, /RAM_OE) = 4.46v (connected for LoROM to 74HC139 pin 9 "2Y3" )
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Kayumba »

Hi again,

After some tests here are the results:

TL866 test:
I was surprise that FM18W08 couldn't be erased with TL866.
When I done "read" and "empty check" , I found that some of "new" FM18W08 was not "empty" (thank's China).
As I can not erase them via TL866, I saved on file of an empty Feram, then I wrote this file to "not empty" feram.
After what I done again "empty check" and it's was recognized like an empty one.

LoROM
16K= not tested yet
64K=OK (Super Mario All Stars + Mario World)
256K= not tested yet

HiROM
16K=NO (Donkey KONG 3)
64K=NO (Secret of Mana 2)
256K=NO (Shiren the Wanderer - Mystery Dungeon 2)

I will continue to do my tests, but it's looks like only LoROM works.
Last edited by Kayumba on Mon Jan 09, 2023 5:15 am, edited 1 time in total.
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Kayumba »

Here is my Final test for FeRAM FM18W08 save fonction :

LoROM
16K= NO (Neugier)
64K=OK (Super Mario All Stars + Mario World)
256K= NO (Fire Emblem)

HiROM
16K=NO (Donkey KONG 3 , Rockman & Forte)
64K=NO (Secret of Mana 2 , Breath of Fire II )
256K=NO (Shiren the Wanderer - Mystery Dungeon 2)
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: SRAM 622256 vs FeRAM FM18W08 way need OR GATE?

Post by Kayumba »

lidnariq wrote: Thu Oct 06, 2022 5:22 pm FM18W08 is a synchronous part, and only cares about the contents of the address change as the /CE signal falls.
Hi lidnariq,
Do you know if it exist « Asynchronous FERAM »?
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by lidnariq »

I know it does not exist
Tomy
Posts: 56
Joined: Sat May 06, 2006 9:19 am
Contact:

Re: SRAM 622256 vs FeRAM FM18W08 do we need OR GATE?

Post by Tomy »

I use FM1808 instead FM18W08 on 74139 and MAD-1 decoder. Both working ok. Both games are use 6264 sram. FM1808 need more power than FM18W08. Need to connect power pin to 5V. I try to use FeRAM on Famicom cartridge too. It work on both MMC1 and MMC3 decoder board.
Attachments
MAD-1_Top.jpg
139_Top.jpg
Post Reply