noob question - 28 pin Winbond W27C512-70 compatible?

[sleepy9090]

Hello
I've been reading the forum off and on for a long time and finally got a break from classes to play around with nes development.

At work we have cable tv boxes with the cmos chips Winbond W27C512-70, They are socketed so I removed some of them, are the useful or can I use these for a homemade dev cart?

Also I've seen several designs for homebrew carts throughout the forums, any recommendations for one to create? Soldering and wiring is no problem, and complication is no problem.

thanks
-Shawn

[Bregalad]

At work we have cable tv boxes with the cmos chips Winbond W27C512-70, They are socketed so I removed some of them, are the useful or can I use these for a homemade dev cart?

They would be usefull only if they have a UV window in the middle and if you have a EPROM eraser at your disposal.
If you can erase the EPROMs, you can then burn new data on them using an EPROM programmer and place them on NES cartridges.

BTW I've *eventually* got a brand new (and expensive) EPROM programmer, and I'm going to be able to test stuff on NES hardware.

[sleepy9090]

hmm,
No way to erase them with an eeprom programmer?

Well I thought I hit a jack pot because I have hundreds of them.

Any pointers or what would be good chips to get, I suppose I can score them on ebays or something

[tokumaru]

I've got a couple of those, they are EEPROMs, so you don't need UV light, the programmer can erase it. They don't even have a UV window, do they?

I got mine here when I bought my programmer a while back, and they work pretty well on NES carts. But since they are only 512Kbits (64KBytes), you'll most likely only be able to use them for NROM and CNROM games, since almost anything other than those boards uses 128KByte ROMs.

[sleepy9090]

ah nice, no they do not have the uv window

they came from old set top boxes,

I was thinking of picking up a usb programmer, so it should erase then? that's great news

NROM and CNROM games, is there any disadvantage to these? What would be the better eprom to get?

I've been studying the board types from reading the 13 pages of posts in this forum. good reading.

[tepples]

There are some small MMC1 games that might as well be CNROM, but at the time, Nintendo apparently could get a better deal on its own custom ASICs than on commodity 74HC161 binary counters. In particular, Tetris (U) and Dr. Mario have PRG and CHR of 32 KB or smaller.

[Bregalad]

EEPROMs can be erased without a UV-eraser. However, they are all called 28Cxxxx or 26Cxxx. Flash ROMs, who starts with 29Fxxx are also electically erasable.

Anything that starts with 27Cxxx is an EPROM. If it lacks an UV-Window then it's a OTP-ROM (one-time programmable) and cannot ever be erased (used for production cost reduction). There is no way you can erase an EPROM without an erased (altough I haven't tried sun-light but I've heard it was a very bad idea). This is a shame as I haven't any free EPROMs at home yet to try my new programmers, I have to wait until monday

[MottZilla]

I've heard it could takes many many days even months of sunlight to erase your EPROMs. Basically you need an eraser, and you need to erase them for a proper amount of time, not too little or too much.

[tokumaru]

I was thinking of picking up a usb programmer, so it should erase then?

Yeah, I have a regular Willem I bought from http://sivava.com/. However, I just remembered that the chips I have are W27E512 (E instead of C), which is also electrically erasable. Sorry about that, but this means I can't be sure your chips will work, although they probably will (I can't even spot obvious differences between their datasheets).

NROM and CNROM games, is there any disadvantage to these?

Yeah, they are the older, simpler and uglier games, the ones that were around by the time the NES was released in the US. There are many good NROM and CNROM games, but they are generally simpler than

What would be the better eprom to get?

If you plan on repeatedly rewriting the chips, I recommend you go with FlashROM. I have a few AT29C040 that work great. They can hold 512KBytes, which is enough for everything except pirate multicarts. For permanent carts, the regulat 27CXXX are probably better. Keep in mind that you can use chips larger than the data they will hold, it's just a matter of correctly wiring the higher address lines and/or replicating the data to fill the entire chip.

EEPROMs can be erased without a UV-eraser. However, they are all called 28Cxxxx or 26Cxxx.

Anything that starts with 27Cxxx is an EPROM.

Well, just take a look at this search then. It clearly says they are electrically erasable.

Bregalad, you shouldn't be so strict. You often post messages saying that something is wrong/impossible/unpractical/whatever based on your current experience and beliefs, without even checking the facts first. It's just a tip I'm giving you... you should give other people some credit, and admit that sometime they may be right, even if at first it goes against your own knowledge.

[loopy]

EEPROMs can be erased without a UV-eraser. However, they are all called 28Cxxxx or 26Cxxx. Flash ROMs, who starts with 29Fxxx are also electically erasable.

49 series memories are also an option.

[sleepy9090]

Ah here is the data sheet for the ones I have at work:
http://www.datasheetcatalog.org/datashe ... 5171_1.pdf

I will pick up a programmer tonight off ebays and start playing. I was thinking about this one:
Extra WIIIIIDE URL


It's overkill but I like to program other chips also.

I was mistaken and thought they were 512 but they are only 64k, bits vs bytes, big difference.

I just got the nes in today and have a copynes coming also. I have a couple bids on some lots of chips, gonna search up some AT29C040. I removed some sockets from a bunch of dead boards at work so they will come in handy.

Are these then limited to one game per cart, or can you get some of the games that use the same mapper and load the rom with say 2 256 games and use a toggle switch or something to go between them?

[tokumaru]

Are these then limited to one game per cart, or can you get some of the games that use the same mapper and load the rom with say 2 256 games and use a toggle switch or something to go between them?

You mean hardware multicarts instead of software multicarts? It should be possible, and cleaner than software multicarts since no game hacking would be required.

However, the mapper isn't the only thing in the board that must match, you have to take into consideration mirroring, extra RAM, batteries and so on. Not everything has to match, for example, most games that use no extra RAM will work on a cart that has it, but keep in mind that some of these items can cause incompatibilities even though the mapper is the same.

I can't say much about the hardware details, but I guess that if you use games smaller than the chips, you could use switches to control the higher address lines and have multiple games per chip. Maybe it's also possible to stack up chips with different games and have a switch select the one that outputs data?

[Bregalad]

Are these then limited to one game per cart, or can you get some of the games that use the same mapper and load the rom with say 2 256 games and use a toggle switch or something to go between them?

I tried that as my first project, I wanted to make a dual DoubleDragon/Catlevania II cart, and I somewhat failed. The games played, but I had completely messed up graphics. This was probably because I did an error anyway, so it should be allright to do this.

NROM and CNROM games, is there any disadvantage to these?

Yeah, they are the older, simpler and uglier games, the ones that were around by the time the NES was released in the US.

Don't forget to tell me if you find Dragon Skill simple and ugly when it's released then.

Well, just take a look at this search then. It clearly says they are electrically erasable.

Bregalad, you shouldn't be so strict. You often post messages saying that something is wrong/impossible/unpractical/whatever based on your current experience and beliefs, without even checking the facts first. It's just a tip I'm giving you... you should give other people some credit, and admit that sometime they may be right, even if at first it goes against your own knowledge.

Well, I guess you're right. I should have double-checked this.

PS : I hate when the thread goes 3 times as wide as originally supposed. Isn't there an option in phpBB to disable this ?

[tepples]

PS : I hate when the thread goes 3 times as wide as originally supposed. Isn't there an option in phpBB to disable this ?

For some reason, I didn't notice the long URL because my copy of Firefox 3.0.1 was "word-wrapping" it. I corrected it anyway. If you find any more page-widening posts, please PM me.

[tokumaru]

Don't forget to tell me if you find Dragon Skill simple and ugly when it's released then.

Hey, don't take it personal! Your game, since it's being worked on now (2008), is being developed under a totally different perspective than the commercial games that used those boards.

See, back when commercial NROM and CNROM were developed (around 1985), the context was very different. The most popular home console was the Atari 2600, so pretty much anything done with NES hardware would look good. As time passed, different home consoles were introduced, and it became harder and harder for the NES to keep up with the quality, but since the standards were raised, there were some pretty good looking games by the time the NES was abandoned.

You, as a gamer, have a lot of experience with old games as well as modern ones, and learned a lot about what makes a good game and good graphics. I'm sure Dragon Skill will look and feel much better than the old CNROM stuff.

I said what I said because it's easy to imagine someone that is trying to build a cart to play NES games and gets really disappointed when they realise they are restricted to the older stuff. Nothing against the hardware itself, it all depends on the people that create content for it, and I'm sure you're competent.