A17 and A18 in larger chips

A17 and A18 in larger chips
by tokumaru on 2006-05-27 (#13498)

Hello guys. I took a TLROM cart to check each pin, one by one, of the PRG and CHR mask ROMs.

Everything pretty much matched the docs on the nesdev page, except for pins 01 and 02 of the PRG chip. Pin 01 of the chip (labeled A17) is connected to pin 25 of the MMC3 (labeled A18). And pin 02 of the chip (labeled A18) is connected to pin 23 of the MMC3 (labeled A17).

The same was true for my SMB3 cart.

So, what pinout is wrong? The mask ROM's or the MMC3's?

Thanks!

by Lloyd Gordon on 2006-05-29 (#13576)

I'd have to take one of my MMC3 carts apart. If you're really stuck pm me and I'll check

TLROM pinout
by Lloyd Gordon on 2006-05-31 (#13655)

I just took my TLROM cart out and looked at it. It's from Shatterhand.

PRG:

Mask:
1) A17 MMC3 25
2) A18 MMC3 23
24) A16 MMC3 21
30) 5V+
31) 5V+

EPROM:

1) Vpp 5V+
2) A16 MMC3 21
24) to PRG 22
30) A17 MMC3 25
31) A18 MMC3 23

CHR:

Mask:

1) A17 MMC3 12
2) /OE NES connector 21
22) GND
24) A16 MMC# 44
30) 5V+
31) /CE NES connector 65

EPROM:

1) Vpp 5V+
2) A16 MMC3 44
22) /CE NES connector 65
24) /OE NES connector 21
30) A17 MMC3 12
31) PGM 5V+

These are correct as I checked them from my own devcart which has worked with at least dozens of ROM's. If you use EEPROM or other memory chips you will have to alter some of the conversion pinouts. These pinouts will work for any EPROM MMC3 mapper 4 devcarts. I have followed them for TLROM, TSROM and TKROM and they all work perfectly. If you have any questions let me know. PM me if I don't answer. I hope this helps.

by tokumaru on 2006-05-31 (#13679)

OK, so pin 1 is indeed A17. I guess pins 23 and 25 of MMC3 are mislabeled in the document from the nesdev page then.

I'll give it a shot and try to make a TLROM devcart. Maybe I'll use the one I thought was ruined. Turns out there is a place where the trace I "removed" goes to the other side of the board, meaning there is a spot where I can solder a wire to. I checked the rest of the board with a multimeter and everything seems to be OK.

Thanks for the help man.

TLROM
by Lloyd Gordon on 2006-05-31 (#13682)

When I looked at my TLROM, I was wondering about what some of the wires were. Turned out I must have ripped a trace right from the NES connector to a PRG pin to a through the PCB solder hole. Anyway I just wired up everything the trace went to and it works perfectly. The cartridges are pretty tough.

by tokumaru on 2006-06-01 (#13690)

He! It was the first time I damaged a cart, so I was a bit traumatized, but now I see it may still be useful. =)

I was wondering if you could take a quick look at my rewiring plans for using a 512KB Flash ROM with an UNROM cart and say if I'm on the right path. This is the pinout for the Flash ROM:
Code:
A18 - 01 32 - Vcc
A16 - 02 31 - /WE
A15 - 03 30 - A17
A12 - 04 29 - A14
A07 - 05 28 - A13
A06 - 06 27 - A08
A05 - 07 26 - A09
A04 - 08 25 - A11
A03 - 09 24 - /OE
A02 - 10 23 - A10
A01 - 11 22 - /CE
A00 - 12 21 - D07
D00 - 13 20 - D06
D01 - 14 19 - D05
D02 - 15 18 - D04
GND - 16 17 - D03

And this is what I intend to do:

And here's a quick description:
.Connect pins 01 (A18), 24 (/OE) and 30 (A17) to hole 16/14 (GND);
.Connect pins 31 (/WE) and 32 (Vcc) to hole 30/28 (+5V);
.connect pin 02 (A16) to hole 24/22 (A16);

Does that look correct to you?

Since I have to rewire only one chip, I figured I'd try this before trying the TLROM.

Thanks for the help!

EDIT: Also, if you got the time and it's not too much trouble, could you take a look at my plans for the TLROM cart, using the same type of Flash ROMs, and check if it looks correct? Here it is:

PRG:

.Connect pin 01 (A18) to hole 02 (A18);
.Connect pin 02 (A16) to hole 24 (A16);
.Connect pin 24 (/OE) to hole 16 (GND);
.Connect pin 30 (A17) to hole 01 (A17);

CHR:

.Connect pin 01 (A18) to hole 16 (GND);
.Connect pin 02 (A16) to hole 24 (A16);
.Connect pin 22 (/CE) to hole 31 (CE)???;
.Connect pin 24 (/OE) to hole 02 (OE)???;
.Connect pin 30 (A17) to hole 01 (A17);
.Connect pin 31 (/WE) to hole 30 (+5V);

Thank you very very much for any help!

by tokumaru on 2006-06-01 (#13691)

Just to make clear why I was confused when I started this topic:

These 2 documents have the pinouts for the MMC3 chip, but they have A17 and A18 (pins 25 and 23) inverted when compared to each other.

http://nesdev.com/rom.txt
http://www.tripoint.org/kevtris/mappers/mmc3/index.html

I guess the one in Kevin's page is correct then.

Connections
by Lloyd Gordon on 2006-06-01 (#13720)

Your TLROM connections seem Ok. I always tie EPROM pin 24 to EPROM pin 22 as I figure that both /OE and /CE should be controlled by the PRG enable. This may not be necessary but I always do it and all the devcarts I have made have worked. If anybody has any thoughts by all means let me know.

I see you are using a UNROM made for 128 KB ROM as I did (Legendary Wings). I highly recommend using the A17 address line. If you don't you will not be able to play any 256 KB UOROM games and your devcarts will lose half the memory. However to use the A17 address line you have to do the following. I am assuming EPROM, you can easily convert to FLASH memory.

Convert UNROM 128 mask ROM to UOROM 256 EPROM devcart:

-there is a resistor just where the top of the EPROM socket will go. Desolder it and resolder it on the other side of the board.
-cut the trace to pin 22 of 28 pin mask ROM (this will become pin 24 of the 32 pin EPROM socket)
-cut the 5V+ connection around pin 28 of the mask ROM (this will become pin 30 of the EPROM socket). I think when I did this I had to cut the 5V+ supply to the 7432 chip so I think I had to put a wire to reconnect 5V+ to pin 14 of 7432. (I noticed a wire in there but I modified the cart about 2 years ago so I can't quite remember).
-cut the ground connections to pins 4 & 5 of the 7432 and pin 6 of the 74161.
-pin 1 of EPROM Vpp goes to 5V+
-I notice I connected NES connector #5 to EPROM socket 27 A8. I have no memory why I did this. Did I rip up a solder trace? Anyway just make sure that EPROM socket pin 27 A8 does connect to NES connector lead 5
-EPROM pin 2 A16 conects to 7432 pin 8
-EPROM pin 31 PGM goes to 5V+ (I do this and it works.)
-EPROM pin 24 to pin 22 (see note above)
-EPROM 17 D3 to 74161 pin 6
-74161 pin 11 to 7432 pin 5
-7432 pin 1 to 7432 pin 4
-7432 pin 6 to EPROM pin 30 A17

This is how I did it and it allows UOROM 256 Kbyte use and it works.
Let me know if you have problems.

by tokumaru on 2006-06-01 (#13723)

Wow, I had no idea that UNROM could be expanded to 256KB. Are there any games that use that?

If the mapper can take 4 bits to index banks, why doesn't it do this by default? Well, I guess most games didn't need that much memory, that's probably why.

Anyway, this mod seems a bit advanced for me right now. I'll keep that in mind (and in a text file!), for when I feel more confident for that kind of stuff.

If you didn't catch any errors in my plans above, I guess I'll try those first.

Thanks again for all the help!

by tepples on 2006-06-01 (#13728)

tokumaru wrote:
Wow, I had no idea that UNROM could be expanded to 256KB. Are there any games that use that?

Among North American games in this table, Best of the Best and Paperboy 2 are UOROM (the 256 KB variant of UNROM).

by Bregalad on 2006-06-02 (#13745)

tokumaru wrote:
If the mapper can take 4 bits to index banks, why doesn't it do this by default?

Because the default UNROM board has room for 28-pins mask ROMs, not 32-pins.

Re: Connections
by sdm on 2016-11-19 (#183121)

Lloyd Gordon wrote:
Convert UNROM 128 mask ROM to UOROM 256 EPROM devcart:

-7432 pin 6 to EPROM pin 30 A17

This is how I did it and it allows UOROM 256 Kbyte use and it works.
Let me know if you have problems.

I noticed that the original cards UOROM address A17 is connected to 74LS32 pin # 04. Or there are various connection methods to get UOROM-256 ?

EDIT: Sorry, A17 to pin #11 of xxxx32.