TLROM Clone PCB + Schematic

FARID · Post by **FARID** » Sun Apr 17, 2011 9:10 am

TLROM Schematic

TLROM PCB

FARID · Post by **FARID** » Sun Apr 17, 2011 12:35 pm

FARID · Post by **FARID** » Sun Apr 17, 2011 1:50 pm

I am really confused about OE? To which pin it must be connected?

This document suggests :

Solder pin 24 to GND (OE)

What do you think?

qbradq · Post by **qbradq** » Sun Apr 17, 2011 4:06 pm

Would that not result in bus conflicts? If /OE is tied to GND then the ROM will always assert data on the data bus, even when you are trying to write to the $8000-$FFFF range (for MMC3 memory mappers). /OE can be tied to GND for the CHR-ROM chip, or to CHR /RD.

Unless the MMC3 is deselecting the PRG-ROM chip via /CE during mapper writes. That would make a lot more sense anyway. If this is the case then yes, tie /OE to GND.

FARID · Post by **FARID** » Mon Apr 18, 2011 6:19 am

I will appreciate you more, if you just make the necessary changes on the picture. Simply use paint so that I can understand better.

Please focus on the following pins :

31 (WE)
24 (OE)
22 (CE)

AM29F040 :

Thanks a lot.

socram8888 · Post by **socram8888** » Tue Apr 19, 2011 7:42 am

/WE (Write Enable) must be high (5V)
/OE (Output Enable) should be tied to ground
/CE (Chip Enable) is connected to the mapper in order to enable and disable the ROM when writting to mapper's registers or to an external SRAM

I can't say anything about that mapper because I don't know the pinout of it (did a DIP MMC3 really existed?)

FARID · Post by **FARID** » Tue Apr 19, 2011 1:28 pm

Are you sure about WE?

According to these pictures :

Both in PRG and CHR (AM29F040) : Pin 31 (WE) is isolated and is not connected to anything.

********************************

According to here :

Pin #02 in CHR-ROM is connected to cart connector pin #21 in NES or pin #17 in FAMICOM (CHR /RD)

Pin #31 in CHR-ROM is connected to cart connector pin #65 in NES or pin #56 in FAMICOM (CHR /A13)

Therefore in CHR (AM29F040) :
Pin 24 (/OE) must be connected to Pin 17 (CHR /RD) of Famicom connector.
Pin 22 (/CE) must be connected to pin 56 (CHR /A13) of Famicom connector.

********************************

According to the AX5202P pinout :

In PRG (AM29F040)
Pin 22 (/CE) must be connected to pin 38 of AX5202P.
About Pin 24 (/OE) there are some information which conflict each other. But for now it seems it should be connected to GND.

********************************

Yes there is a pirate clone from MMC3 called AX5202P :

socram8888 · Post by **socram8888** » Tue Apr 19, 2011 1:35 pm

I have a MMC3 clone in DIP package too, but marked "9112". I'm unsure if the pinout is the same, anyway

/WE i'm 100% sure that it must be connected to VCC (high). My MMC3 pirate cartridge has these connected to VCC. Leaving it floating may cause malfunctioning

EDIT: Mine is completely different than yours, its pinout is the same as the original MMC3

FARID · Post by **FARID** » Tue Apr 19, 2011 9:23 pm

socram8888 wrote: /WE i'm 100% sure that it must be connected to VCC (high). My MMC3 pirate cartridge has these connected to VCC. Leaving it floating may cause malfunctioning

Are you Judging about WE according to a real TLROM?

Please pay a close attention, I want to make a clone of TLROM by using two AM29F040 (PRG/CHR) and one AX5202P (MMC3). Pinout of these componnent are different from mask roms which are like this :

PRG Mask rom pinout :

CHR Mask rom pinout :

********************************

If anyone have a MMC3 cartridge plaese take a high quality shot from both sides and post it here. Please write the name of its game too.

********************************

As a conclusion it seems there are three possibilities about /OE and /CE for AM29F040 (as a PRG) :

1.
Pin 22 (/CE) of AM29F040 <--> Pin 38 of AX5202P
Pin 24 (/OE) of AM29F040 <--> GND

2.
Pin 22 (/CE) of AM29F040 <--> Pin 24 (/OE) of AM29F040 <--> GND

3.
Pin 22 (/CE) of AM29F040 <--> Pin 24 (/OE) of AM29F040 <--> Pin 38 of AX5202P

TmEE · Post by **TmEE** » Tue Apr 19, 2011 11:31 pm

!WE must be pulled high, otherwise you'll have nothing happening. The chip is most likely CMOS aswell so there's no escape from pulling it high.

socram8888 · Post by **socram8888** » Wed Apr 20, 2011 12:34 am

No, I'm comparing it with my pirate MMC3 cartridge that uses 27C010

/WE is an active-low Write Enable. As you're not going to program nor write the ROM on-the-fly on the NES, you should tie it to 5v (VCC)

FARID · Post by **FARID** » Sun Apr 24, 2011 12:02 am

So it should be like this, right? Any kind of advice or suggestion would be greatly appreciated.

Front :

Back :

Component :

MMC3 = AX5202P

PRG and CHR = AM29F040

C1 = 4.7uF 16V electrolytic (10uF is OK, higher volt ratings are OK)

C2 = 0.1uF ceramic capactor (6V rating minimum)

CC = 220pf capacitor (5V or above)

Connector :

TmEE · Post by **TmEE** » Sun Apr 24, 2011 1:10 am

The capacitors can be anything as long as the voltage ratings are 5V or above.

The cart boards seem to look OK to me

FARID · Post by **FARID** » Sun May 01, 2011 7:45 am

As far as I had researched :

No need to use C1, C2 and CC. Without these capacitors game runs OK. If you know some advantage of using these capacitors tell me. I have heard capacitors are for power filtering but what will happen if I don't use them? Will it damage to the chips over time, if I not use them?

No need to connect WE to +5V. WE is short form of Write Enable and someone told me it is just for programming purpose. Although game runs OK while WE connected to +5V, it is better not connect it to +5V, I think in this way chip is protected from any undesirable change of data inside it.

Why there is not any pin called CHR A18? Somehow I suspect that CHR A18 is pin 01 on AM29F040 and pin 39 on AX5202P but I need someone confirm it.

Large Display view of TLROM Clone Schematic

And again any suggestion or advice would be appreciated. Everyone keep up the good work, we are almost there!

socram8888 · Post by **socram8888** » Sun May 01, 2011 1:26 pm

Actually, you should NEVER leave an input unconnected. These ICs don't have any pull-down/pull-up resistor, so this can cause the IC to glitch