For what for EPM3128ATC100 on Chinese SNES repro?

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Kayumba
Posts: 145
Joined: Sun Mar 01, 2020 2:36 am

For what for EPM3128ATC100 on Chinese SNES repro?

Post by Kayumba » Mon Apr 05, 2021 3:41 pm

Hello everyone,
I would like to know why Chinese SNES reproduction uses this chip?
EPM3128ATC100
Image

Do you think that they are using this chip only like voltage translation" ?
Can it be possible ?

Image

I found this PCB repro on Ali,
Here is the list of components :
- EPM3128ATC100
(what role ?)

- S29GL512 (3v) 512Mbit
(Flash chip for Game)

- AMTRON FM1808-70-SG | Memory; FRAM; parallel; 4.5÷5.5V; 70ns
(Fram chip for storage saves)
Image

- 12F629
(CIC region unlock)

- AMS1117
(Voltage regulator 5v to 3,3v)
I think it’s here only to supply Flash chip S29GL512

- capacitors : 2x 16v 47uf

- one resistor (don’t see valu)

Don’t see any « diodes »

Kayumba
Posts: 145
Joined: Sun Mar 01, 2020 2:36 am

Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by Kayumba » Sun Apr 11, 2021 12:14 pm

EPM3128ATC100
Its « Complex Programmable Logic Devices » (CPLD).
I think that they using it like Mapper

krzysiobal
Posts: 843
Joined: Sun Jun 12, 2011 12:06 pm
Location: Poland

Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by krzysiobal » Sun Apr 11, 2021 12:28 pm

Maybe except providing mapping features (the same what 74139 does in HI ROM cart + some other mapping if this is multicart), it also acts as a 5V->3.3V buffer for the ROM chip which is not 5V tolerant? Don't see all the connections.

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poorstudenthobbyist
Posts: 231
Joined: Fri Jun 24, 2016 4:20 pm

Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by poorstudenthobbyist » Sun Apr 11, 2021 12:52 pm

Kind of weird that they'd take the precautions of proper level translation without chamfered edges or hard gold edge connector.
Check out my website for NES, SNES, and Genesis tutorials here. And visit my store for some custom tools and boards for making games here.

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krzysiobal
Posts: 843
Joined: Sun Jun 12, 2011 12:06 pm
Location: Poland

Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by krzysiobal » Sun Apr 11, 2021 1:56 pm

poorstudenthobbyist wrote:
Sun Apr 11, 2021 12:52 pm
Kind of weird that they'd take the precautions of proper level translation without chamfered edges or hard gold edge connector.
Hard gold edge connector triples the cost of PCB (at least at jlcpcb.com).
They also don't want to make chamfered edges for cheap boards (those at default 10x10cm with enig surface)

sdm
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Location: Poland

Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by sdm » Sun Apr 11, 2021 2:42 pm

Maybe the PCB is universal for LOROM / HIROM games and this chip is responsible for that (it switches LOROM / HIROM games automatically)

Kayumba
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Joined: Sun Mar 01, 2020 2:36 am

Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by Kayumba » Mon Apr 12, 2021 1:56 pm

sdm wrote:
Sun Apr 11, 2021 2:42 pm
Maybe the PCB is universal for LOROM / HIROM games and this chip is responsible for that (it switches LOROM / HIROM games automatically)
I think so too.
But for me it’s expensive solution.
Should try and see how it’s possible to program.

krzysiobal
Posts: 843
Joined: Sun Jun 12, 2011 12:06 pm
Location: Poland

Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by krzysiobal » Mon Apr 12, 2021 3:15 pm

This memory has 512 Megabits (64 MB), so it must be a multicart (or at least a PCB designed for multicart purposes), it can't be achieved by single 74139.
BTW. This cpld costs 1$, is it really an extravagance?

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