how to use Use 27C040 in PCB for M27C801

[Kayumba]

Hi,

I have PCB for M27C801 swap bin datas.
I use every time "SwapBin" method to my ROM files with SNES ROM Utility and program it with TL866.

All works great!

Now I would like to use 27C040 EPROM for 4Mbit games on the same PCB, but I dont understand why it's dont works?

I tried two methods without success :
1 - Program directly .smc files without passing by SNES ROM Utility to make SwapBIN.
2 - Do SwapBIN with SNES ROM Utility to my 4Mbit file even if its writing for M27C801, see here:


I dont understand, cause if I see here, the pinout is the same like in M27C801, see here:

[poorstudenthobbyist]

Swapbin switches A17 and A19, which on the 27C080 are pin 30 and pin 1 respectively.
The 27C040 doesn't have an A19 pin. Pin 1 for the '040 is VPP, which is not an address pin. So using swapbin on the ROM file basically erases part of the game because you won't be able to access it on the '040.

[Kayumba]

Swapbin switches A17 and A19, which on the 27C080 are pin 30 and pin 1 respectively.
The 27C040 doesn't have an A19 pin. Pin 1 for the '040 is VPP, which is not an address pin. So using swapbin on the ROM file basically erases part of the game because you won't be able to access it on the '040.

Thank you for answer.
I see, better know.

So how can I do to use 27C040 without expanding file to M27C801 Eprom ?
If with SwapBIN method it erase some parts of the game, so it's should work if I program directly .SMC file with TL866, isn't it ?

[poorstudenthobbyist]

Just program it normally and rewire the 040 pins to the Mask ROM pinout so they match. Leave out any address pins over A18, since the 040 only goes that high.

[Kayumba]

Just program it normally ...

OK

...and rewire the 040 pins to the Mask ROM pinout so they match.

Rewire all 40 pins ?!
Why I have to rewire all 40 pins if the only difference between 27C040 and M27C801 are in one pin, pin1 (VPP vs A19)



Or you mean, rewire the pin n°40 of Mask ROM ?

Leave out any address pins over A18, since the 040 only goes that high.

Like that ?

[poorstudenthobbyist]

I meant the 27C040 pins, not 40 pins haha

Put it in the 32-pin socket as you normally would (or in the 36-pin socket, put it in so pin 1 on the ROM is pin 3 on the socket), but bend up the different pins between the EPROM and the socket.

Comparing the two shows these different signals (remember the only difference between 080 and 040 is pin 1, so I'm just using this pic from my tutorial)

Pin 1, pin 2, pin 24, pin 30, pin 31. Bend these up, and put the chip in the socket.

Pin 1 is VPP, so just tie that to VCC (pin 32).
Pin 2 is A16, so wire that bent-up pin to hole 24.
etc. Just match the different names, and wire them properly.

[Kayumba]

I meant the 27C040 pins, not 40 pins haha

Put it in the 32-pin socket as you normally would (or in the 36-pin socket, put it in so pin 1 on the ROM is pin 3 on the socket), but bend up the different pins between the EPROM and the socket.

Comparing the two shows these different signals (remember the only difference between 080 and 040 is pin 1, so I'm just using this pic from my tutorial)

pindiff.png

Pin 1, pin 2, pin 24, pin 30, pin 31. Bend these up, and put the chip in the socket.

Pin 1 is VPP, so just tie that to VCC (pin 32).
Pin 2 is A16, so wire that bent-up pin to hole 24.
etc. Just match the different names, and wire them properly.

I meant the 27C040 pins, not 40 pins haha...

Great !
Thanks.

I will try to do it tonight

[Kayumba]

It's do not work.

Maybe cause my PCB is already do some connection between M27C801 and Mask ROM ?
The fact that my PCB work only with Swapped BIN method, it's it changes some thing ?

[poorstudenthobbyist]

Did you program the ROM without swapbin or with it? You should do it without.
All the address pins are going to their proper sockets?

[Kayumba]

Did you program the ROM without swapbin or with it? You should do it without.
All the address pins are going to their proper sockets?

I program directly .SMC file without SwapBIN.
27C040
Pins bended :
Pin 1 (VPP)
pin 2 (A16)
pin 24 (OE)
pin 30 (A17)
pin 31 (A18)

Other pins are in socket.

Bended pins connections :
27C040______________________Mask ROM
Pin 1 (VPP)--------------> Pin 32 (VCC)
pin 2 (A16)--------------> Pin 24 (A16)
pin 24 (OE)--------------> Pin 31 (OE)
pin 30 (A17)--------------> Pin 1 (A17)
pin 31 (A18)--------------> Pin 2 (A18)

[Fisher]

If you want to swap yout ROM's pins, there's the great Farid's EPROM pin swapper.
The difference is that you need to manually assign the pins you wish to swap.
It worked great for me in the past, and probably will do the same to you.
AFAIK, the source code is included.

[Kayumba]

If you want to swap yout ROM's pins, there's the great Farid's EPROM pin swapper.
The difference is that you need to manually assign the pins you wish to swap.
It worked great for me in the past, and probably will do the same to you.
AFAIK, the source code is included.

Thank's.

So in this soft I should follow the same pins connections , like here?
27C040______________________Mask ROM
Pin 1 (VPP)--------------> Pin 32 (VCC)
pin 2 (A16)--------------> Pin 24 (A16)
pin 24 (OE)--------------> Pin 31 (OE)
pin 30 (A17)--------------> Pin 1 (A17)
pin 31 (A18)--------------> Pin 2 (A18)

I remember that I already used this soft, but I it was impossible to open .SMC file.

[Fisher]

Oops...
Maybe it only works with .nes or .bin files, I'm not sure.
There's also Joe's command line tool.
It has only the source code, wich needs to be compiled. It works great too.
In this post Joe gives a brief explanation on how to use the program.
Hope you can figure it out and finish your repro.

[poorstudenthobbyist]

You can change the extension of a .smc file to .bin and it'll retain the information.

I'm not sure, that rewiring should work just fine. Maybe you have a different problem that's preventing the game from running? Bad EPROM, solder joints? Not sure. Maybe attach some pictures?

[tepples]

You still need to strip the 512-byte copier header before programming the EPROM.

In a sane world, a tool to strip the header would change the extension from .smc (for Front's Super Magicom copier) to .sfc (Super Famicom binary), and the .sfc is what you'd burn. Compare Genesis, where the rule is that stripping the header and deinterleaving a .smd format ROM (for Front's Super Magic Drive copier) produces a .gen (Genesis binary). So set the ROM conversion tool to just strip the header.