For what for EPM3128ATC100 on Chinese SNES repro?

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

For what for EPM3128ATC100 on Chinese SNES repro?

Post by Kayumba »

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
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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by Kayumba »

EPM3128ATC100
Its « Complex Programmable Logic Devices » (CPLD).
I think that they using it like Mapper
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krzysiobal
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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by krzysiobal »

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.
poorstudenthobbyist
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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by poorstudenthobbyist »

Kind of weird that they'd take the precautions of proper level translation without chamfered edges or hard gold edge connector.
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krzysiobal
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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by krzysiobal »

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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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by sdm »

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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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by Kayumba »

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.
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krzysiobal
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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by krzysiobal »

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?
Kayumba
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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by Kayumba »

Anybody tried to create and program Mappers with those chip ?
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happysoul
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Re: For what for EPM3128ATC100 on Chinese SNES repro?

Post by happysoul »

Kayumba wrote: Sat Apr 17, 2021 10:09 am Anybody tried to create and program Mappers with those chip ?
Old chips are not product, like MMC1 3 5 ... vrcX ,so we can not get controller chip
to support large ROM read, use this cpld as a controller to switch address
maybe games has been modified to suit this pcb
cpld can be program as a black box,include many 74chip or other switch module

if use fpga, mmc5, konami vrcX ... can be replaced.
its hardly to us, light a led with a cpld/fpga chip...
program language : VHDL / Verilog

somebody maybe write code for cpld,but for sell ... so... you can see this image of pcb from #1
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