Question on ID'ing Eproms, Roms, eeprom, etc.

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I was wanting to know if somebody could help me id eproms and other proms. Would like to know know how to ID them and what ones are compatible with them. For example say you have D27512J-2, Can I use any 27512, M5M27c512, 27c512, etc. series eproms. For I am not sure what the J-2 stands for. Or is it just meaningless. I am just kinda confused on how I guess you read them and then which ones to use. after say for example the 512 or 64 or 256. Dont know if the letters and numbers mean anything after it.. if it does is there a website to goto to know what the meanings are.


thanks in advance
 
Typically you can replace any 27512 with a 27C512. The C stands for CMOS, they are usually faster than the standard eproms. The cmos eproms program at a lower voltage. The most important thing to look at is the speed of the eprom. That J-3 is the package code and speed. J usually means ceramic package, most eproms will be ceramic. For the speed you should check the datasheet. Most codes are simple, the -3 will usually mean 300ns. However, there are some this does not apply to.
www.datasheetarchive.com is your friend. In some cases they even show sub part numbers but use them as a general guide only. Eproms are pretty straight forward and generally pretty standardized.
 
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one more question

It kinda goes with the eprom id part..when you read the eproms. and your programmer can't identify the eprom. and you have to find it in a list. does that go true with reading a eprom. if it says M2764-20 and you don't have a M2764-20 in the list, can replace it with say a d2764a that is in the list.

thanks in advance
 
if it says M2764-20 and you don't have a M2764-20 in the list, can replace it with say a d2764a that is in the list.

thanks in advance

Yes, the letter at the beginning just tells you the manufacturer. You gotta watch that 'A' at the end, they program at a lower voltage but are otherwise the same as far as function goes.
 
Any letters before the "27" part is usually manufacturer info and not too important.

If it has a "C" after the 27, it means CMOS.
This means they are usually newer, faster, and require less power to program and run.

You can replace a "non-C" with a CMOS eprom,
but it is not recommended to replace a CMOS with a non-CMOS.

The digits after the 27 or 27C are the eprom size in BITS

2716 = 16kBits = 2Kbytes
2764 = 64kbits = 8Kbytes
27c512 = 512kbits = 64kbytes
27c010 = 1 Mbit = 128Kbytes

If the next code is the letter "A" , it means it programs at a lower voltage.

For 2716A and 2732A that means 21V rather than 25V.
For 2764A and 27128A that means 12.5V rather than 21V

Starting with 27256, pretty much every eprom after that programs at 12.5V.

After that there is usually a dash " - "

Then the eprom speed.
There is no standard for eprom speed markings, so common sense prevails.

Older eproms (2716-2764) range from 100-450 ns.

So 2716-1 would be 100ns, 2716-35 would 350ns, 2732-45 would be 450ns

Sub-100ns are only found on 1Mb eproms and up.

So a 27c040-45 would be 45ns, 27c010-120 would be 120ns
(...although I have seen 27c040-12, meaning 120ns ).

In fact, the fastest eproms I've ever seen are 45ns.

You can always use a faster eprom, but not a slower one.
(...I know some application that need 120ns or better, so a 150ns won't work...)

Hope this helps.

Cheers,
Steph
 
There are only a few chips that are odd that you need to watch out for...

2716 = +5v EPROM
TMS2716 (made by TI and 2nd sourced by Motorola) = +5, +12, and -5v EPROM

You'll only find those TMS2716 chips on old old old gear from the late 70s.

AND...

27C1000 / 27C1001 EPROMs

These 1Mb EPROMs are strange in that when the 1Mb ones first came out there were 2 different pinouts available. The first is the non-JEDEC version where they were made to be a 32 pin programmable chip that would replace a 28 pin mask ROM with a minimum of effort. The other is the JEDEC pinout version which is pin compatible with the 27C010 EPROM.

The problem is that some manufacturers called the JEDEC version the 27C1000 and non-JEDEC version the 27C1001 and other manufacturers were just the opposite. Yet another one called their non-JEDEC version the 27C301.

The easy way to tell which is which is to blank check the chip as a 27C010. If it passes it's JEDEC. If it fails at exactly the 1/2 point through the chip then it's the non-JEDEC one.

:)
 
See how easy all of this is? I have the same problem. Fortunately channelmanic is local to me so I can always bug him for an answer. Now wait till you try to find PROM substitutes.
 
See how easy all of this is? I have the same problem. Fortunately channelmanic is local to me so I can always bug him for an answer. Now wait till you try to find PROM substitutes.

That was going to be my next question is what is a good way to be able to tell how to substitute them..


thanks in advance
 
I was to thank everybody

Just wanted to think everybody for there input. New to all of this and wanting to learn. just need that push to get me in the right direction.You Klovers are the best. So, anymore input is greatly appreciated.

thanks
 
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