SpritesMind.Net

Under the condition that I use the same style flash eprom size as what was in the cart, possibly push the code through ucon64 if necessary for header info. Clip the old chip off the board, desoldier and clean board up. Burn chip and soldier the chip to the board. Is there anything else I might need to do? I'd like to recycle a few of the duplicate sports games I have and figure I could finally put them to better use! LOL Thanks! - Daryl

sure you can do it, you just need a Flash chip with same pinout, and you need to map the !WE line to somewhere too.

Map the !WE line to the HUHWHAT??? What exactly does that mean? I'm a bit of a newbie to this one... How does one go about that?

You must disconnect 'write enable' pin of flash chip from cart board to prevent accidental erase of data. You can just bend out this pin to not solder it in board.

Connect /WE pin to the Vcc , thats it!

You guys are awesome! I understand totally now what Shiru means by not soldering the Write Enable pin to the board, but what does Jorge mean by connect it to the VCC? What's a VCC? Also looking at this document, Sega Programming FAQ October 18, 1995, Sixth Edition - Final, I saw the pin outs for a 40 and 42 pin chip, but neither shows exactly on each layout what the /WE pin is... Which pin is it on a 40 and 42 pin chip? Thanks for all your help! I LOVE THIS BOARD!

Vcc is the +5Volt source

A 42pin ROM chip similar to those on the game carts:
http://www.alldatasheet.com/datasheet-p ... 1602B.html

There is no explicit Write enable, but applying 12.5V to the Vpp pin puts the ROM in program mode

For starters, that data sheet is a very helpful piece of work. I see now what the VCC pin is on both type of chips.

We want to keep the board OUT of program mode correct? In other words when you say there is no explicit write enable, but applying 12.5V to the VPP pin puts the ROM in program mode means we'd want to bend up the VPP pin to keep it out of program mode, or soldier a wire from the VCC to the VPP and give it power?

I guess I'm confused to why Shiru says bend the /we pin up and out of the way, and you say connect it to the VCC? Can you do either or? Also Jorge, I still don't see on the schematic which pin is the /we pin... is there another name on the schematic for the /we pin like the VCC or VPP and I just don't know this?

Thanks again! - D

WE is like VPP pin, because in the ages of mask roms/ UVeproms (yeah like thousands of years ago ), they required a higher voltage in programming mode because it was to blow little fuses inside a virgin memory cell, thats why there is no explicit write enable... It is a programing voltage... If Vpp is present, the ROM would sample the 0's at the data bus and blow its internal microfuses at the specified address...

But now with flashes, the Vpp usage was tossed away, because it wasn't convenient to have 12.5V in a circuit powered only with 5V, and so they (the flash enginners) put in the Write enable pin, just like RAMs

Since Write enable is active @ 0V for sure, I was telling you to wire it to Vcc so it is always inactive... leaving inputs disconnected isn't good practise, especially theese that affect the chances to work (leaving unused gates unwired probably has no implication on the used ones)

Yea for megadriving the ROM is not to be in programming mode

If your chip has a Vpp pin -> wire it to Vcc
If your chip has a /WE pin -> wire it to Vcc

That explains everything... That's exactly what I needed to know to understand exactly what was going on with that... So you can bend just the VPP or WE pin up and not use it, it's just not the best practice...

Last question (I hope) do you still bend the VPP or WE pin up and out of the way, and then soldier a wire from it TO the VCC pin that is plugged in or do you not bend ANY pins up and still wire the VCC to the VPP? Dumb question I'm sure, but still have to ask... LOL

Thanks for all your help Jorge, I really appreciate it!

Any other q's, I'll let you know... - Daryl

It only depends of the pinout of your chip... The roms in the original game carts have the Vpp pin tied to Vcc, so it's protected from unwanted programming. If your chip is equal to those original ones then it isn't needed any pin-bending...

If you could tell what chip you have it was waaaaayyy easier

I think I didn't understand your question very well

Nope, you understood perfectly... I really appreciate everyone's help here... If I need any additional help in the near future, I certainly know who to turn to... Thanks again everyone! I'll let you know how my experiments go! Later! - D

I have my Flashcarts !WE connected to !LDSW and since Flashchips require commands, accidental stuff is very unlikely, and I have had absolutely no problems so far.

Nice post, I was actually looking to do something like this, I ordered a willem programmer, and now I'll need to order the 42 pin EPROM adapter, I'm thinking in using UV EPROMS. Can you post an image of the board with wire connected to the vcc? since I really don't know what the vcc is on the board. I have lots of sports cartriges around and was thinking of doing the Monster World IV cart.

Thanks

Edit: I was thinking in buying these, I would like to know if these can be used:

M27C160 42 pin

Extracted from the aucion on ebay:

"The M27C160 is a 16 Mbit EPROM offered in the two ranges UV (ultra
violet erase) and OTP (one time programmable). It is ideally suited for
microprocessor systems requiring large data or program storage and is
organised as either 2 Mbit words of 8 bit or 1 Mbit words of 16 bit. The
pin-out is compatible with a 16 Mbit Mask ROM."

That chip seems to fit perfectly. How much does one cost ?