27512 J-2 chip manufacturer EPROM questions operation wolf

robgill2008

Member
Joined
Aug 15, 2010
Messages
80
Reaction score
0
Location
Paducah, Kentucky
27512 J-2 chip manufacturer EPROM questions operation wolf

I am having difficulty checking and programming some EPROMS. I have 7 questions about programming this chip using Needhams EMP-11. If you can answer any or all please help.

68884_168068989872447_100000080412818_535912_1565444_n.jpg

1. Who is the manufacturer of this chip?

2. Can I use any Manufacturer from the list on the programming software to program this 27512 device.

3. I have tried just about every Manufacturer and 27512 that I can find in the device selection list and every time I do a checksum...I get "00FF000" (I have tried two different 27512's pulled from my op wolf main board.) Something seems fishy about this to me. What's up with that?

4. I peeled back the tape and I assume that these are UVEPROMs. Is this correct?

5. Can I use flouresent light or set them out in the sun for an extended period of time to erase them?

6. Should they be erased and preform a "blank check" on them before programming them?

7. After erasing one will the checksum value read "00000000" ?

Any help would be greatly appreciated.

Control^Z
 
1. Who is the manufacturer of this chip?

Intel - hence the big "i"

2. Can I use any Manufacturer from the list on the programming software to program this 27512 device.

Usually yes - you only have to worry about the programming voltage - so avoid chosing an AMD chip as some of those use 21V which will kill this chip - 12V or 12.75V is the common prog voltage, so if you have a USB eprom programmer you will need to plug in its external PSU to write to chips.

3. I have tried just about every Manufacturer and 27512 that I can find in the device selection list and every time I do a checksum...I get "00FF000" (I have tried two different 27512's pulled from my op wolf main board.) Something seems fishy about this to me. What's up with that?

No idea - dump the eprom and use WinRomIdent to confirm the dumped data.

4. I peeled back the tape and I assume that these are UVEPROMs. Is this correct?

Yes

5. Can I use flouresent light or set them out in the sun for an extended period of time to erase them?

You would need about 3 months out in the sun to erase them, I tried it a while back, left one out in the Australian sun (40 degree day) and it didn't even lose a bit.

6. Should they be erased and preform a "blank check" on them before programming them?

Yes

7. After erasing one will the checksum value read "00000000" ?

I would think so yes, either 00000 or FFFFFF
 
Manufacturer is Intel..that big "i" is their logo.

Usually good to choose proper manufacturer in software as each one has their little quirks.

Not sure on the checksum thing other than make sure your not putting it in backwards. They could be bad or have bit rot too.

It is a uv eprom but their just known as eproms. The newer ones are called eeproms...two e's stand for "electrically eraseable". Normal eproms are just "erasable prgrammable read only memory", and in most cases uv erasable.

Cant erase with a fluorescent light or the sun, you need an eprom eraser or to build one using a uv-3 bulb. If you do build something beware the uv light is harmful to your eyes! You shouldnt look at it. You can get cheapie erasers for $20 on ebay though.

Yes they would have to be erased and blank checked before programming. I wouldnt worry about crc when blank the software should verify it.

Hope that helps!
 
Thanks guys.

Well while you guys were reading my last post and answering them, I was out in the garage with the old PC with a LPT1 parallel port with no internet connection.

You would think that I would know that the F**#ing "I" stood for intel, however, Back in the day, I was building Pentium one, two and three PCs and I would swear they spelled out Intel on those chips. Hell, I have been wrong before...whats new?

Anyway, I figured out the "fishy" part of the checksum error. Dumbass me was registering the chips towards the top of the programmer. I looked at the pretty diagram on the damn programmer and noticed that all the chips register at the bottom.

Ok, the four INTEL 27512 chips that I pulled and ran a checksum on matched the checksum of the MAME files. IC 29,30,39 and 40.

That leaves 2 NEC chips....hey that is in the Manufacturers list for this programmer....however these two devices are not found in the NEC device list....IC 13 which is a NEC 8751XD and IC 72 which is a NEC 8748XD.

Now what do I do? Please don't tell me to go buy another board....I am trying to learn a little.

As for the actual board, I really don't see any brown spots or anything that looks like it has been damaged by heat.

I do have a working machine and have found that the Audio Board is good on this set.

Again any help would be greatly appreciated.

Control^Z
 
Post a photo of the board, never heard of anything with those NEC part numbers.
 
programming NEC

Rather than taking a picture of the board right this second, I noticed this printed on the board "IC 13......MN234000." This Nec chip also has B20-13 printed on it but I didn't think it was relavent.

The other NEC chip "IC 72 also has MN234000" printed on the circuit board beside the chip This chip has B20-14 also printed on it and just like the other I didn't think it was relavent.

Does that help? If not I will get you a good picture of both chips.

Control^Z
 
It does indeed help, 23Cxxx means its a mask ROM, which are often only labelled with the manufacturers name and a code that only made sense to them years ago. Mask ROMs are ROMs that are made with the contents already inside them, they are etched with a photomask (hence the name) in the same way chips are made today but the data is part of their structure from birth so they were never actually programmed. They are often used on arcade boards for non-executable code, ie graphics or sound data, code that is not likely to ever change. On mass produced boards it was cheaper to use mask ROMs as EPROMS were insanely expensive. Executable code was usually in EPROMs so bugs could be fixed without throwing anything away. Gfx data was unlikely to ever be wrong and need changing, tho there are instances of that, like in Shadow Warriors where the main characters socks change colour when he is walking or when he is kicking.

The bad news is that often their pinout is not the same as a standard eprom of the same size as they saved space by ditching the pins used for programming the eproms.

The good news is that MN234000 chips are pin for pin compatible with 27c400 eproms, so you can read them as those.

The bad news is you will probably need to desolder them to test their contents as they are almost certainly not socketed, if this is not done carefully/quickly a long drawn out desoldering can kill them too as the wont like lots of heat.

What is the fault on your board? If its gfx or sound related then the masks are definite candidates as they are much more prone to failure than EPROMs, but if the board wont run it is unlikely to be the masks.
 
Last edited:
Great information

Wow! Thank you, I never heard of Mask ROMS but I totally understand. In college back in 97, I actually was in a VLSI class laying out the transistors for an 8 bit counter that wound up being 1/4 of the total chip 3 of my other classmates had their 1/4 to layout. I had programed PALs and GALs. We didn't have to do much research on this programming they would hand us a chip and walk us through the software. My school just didn't teach much of what I have run up against in the real world. I never got a job in electronics, I always worked as a technician in manufacturing plants or at a desk crunching data. No fun stuff like this. Believe it or not I actually inteviewed with the big "I" intel straight out of college. Fortunately in the interview they didn't ask me what symbol they marked their chips with. Didn't matter, I didn't have the chops for them anyway!

Actually those two mask rom chips are socketed.

When I fire up this board the screen is just a garbled mess with no sound. But the other night I swapped the "bad" sound board into my "good" main board and it proved to work fine. So somewhere on this main board, I hope, is the problem. These are the only two chips that I can pull. Except for a large "TAITO" chip that I would asumme is proprietary.

When I try to read in these mask roms what device should I use or will I see that 234000 device in my NEC device list?

Thanks again,
Rob
 
Please put your city in your profile as you may have a KLOV'er in your neighborhood who is willing to help you or teach you something.
 
Location

I thought I had put that info in when I joined this forum. I just put that information in my profile. Paducah, is in far western KY. Where the tip of illinois touches ky. 3 hours from st louis MO, 3 hours from Louisville KY, and 2 hours from Nashville TN.

Rob
 
No 27x400 in NEC device list. Maybe I can find one under another manufacturer.
Rob

For reading chips it doesnt really matter what manufacturer you choose, the only warning comes when programming chips, the prog voltage was not standard and some makers used higher voltages than others. So if you happen to program a chip using a setting for another manufacturer you might hit it with too high a voltage and blow the chip. Reading is safe tho.
 
Nec 27c400 Needhams emp-11 operation wolf

Ok, I have to take the wife out to eat tonight. So, I won't be able to search my device and manufacturer list for a day or so. Please come back to this thread so I can keep learning. Thanks again to all you for your help thus far.

Rob
 
Intel 27c400 Needhams emp-11 operation wolf EPROM

Well running a checksum after selecting an Intel 27C400 on IC 13 and IC 72 and comparing that to the mame ROMs it looks like I have hit a brick wall. The checksums match. The only other chips that I could check would be the ffour PAL16L8's. I am not sure what the checksums should be for these. I guess I could pull those same chips from my known working operation wolf board and read the checksums on them. However, the way my luck has been running I don't think I want to do that.

Here is the picture of what this messed up board does in my known working machine.

73502_167625299916816_100000080412818_533582_7252969_n.jpg


Other than finding a know working board. Do any of you have any other suggestions?

I have learned much on this first endeavor. So it's not a total loss, It has been quite fun actually.

Thanks again,
Rob
 
Your fault looks very much like a crashed board, which is more often than not due to bad static RAM chips. Its very rare for EPROMs on a board to be bad, but as they are socketed its often the only thing you can test without rather specialised gear. If the board was on my bench I would poke a scope at the mains SRAM output pins, and probably desolder them for a test outside of the board.
 
Your fault looks very much like a crashed board, which is more often than not due to bad static RAM chips. Its very rare for EPROMs on a board to be bad, but as they are socketed its often the only thing you can test without rather specialised gear. If the board was on my bench I would poke a scope at the mains SRAM output pins, and probably desolder them for a test outside of the board.

So how much will it cost me to ship you my main board?

Rob
 
Back
Top Bottom