Buying 2732A eproms

[Dean]

Brand new to this stuff, so please, bear with my ignorance...

I went looking to purchase a small stash of eproms, but honestly, I don't know what I'm looking at. For instance, I did a search at jdr.com and it came back with 3 items:

- EPROM(2732A-2F1)4KX8 21VPPG 24CERDIP $6.49
- EPROM(D2732AF1)4KX8 250NS 21VPPG 24CERAM $5.49
- EPROM(2732AF1) 4KX8 NMOS 450NS 24DIP $4.29


At jameco.com I got these (all "refurbished"):

- IC, EPROM, 2732A-20, VP:21V MFG#: 2732A-20 PRICE: $6.49
- IC, EPROM, 2732A-25, Vp:21V MFG#: 2732A-25 PRICE: $4.99
- IC, EPROM, 2732A-45, Vp:21V MFG#: 2732A-45 PRICE: $3.99


What is the difference with these? The "NS"? What is NS, as in 250NS? Or more importantly, what exactly should I be looking for?

I gotta lot to learn here...

 

[ijames]

ns is nanoseconds, so 250 ns means that chip has an access time of 250 nanoseconds. Our ecms are so slow that the 450 ns chips are fast enough. The faster ones also work, but not any better, and they do cost more .

 

[Dean]

Thanks, Carl.

How about the numbering on the jdr.com stuff (2732A-2F1 vs. D2732AF1 vs. 2732AF1). Just a manufacturer's numbering system identifying the various NS? And what is CERDIP, and CERAM, and DIP?

One more thing, I already inteded to get new eproms, and now I have been alerterd to a lower (50%) success rate with re-burned eproms. Have others here experience that much trouble?

TIA!


Dean

 

[87GN_70GS]

DIP means Dual In-line Package (the chip shape)
CERAM means Ceramic (the substance the outside of the chip is made from)
CERDIP means Ceramic Dual In-line Package

 

[87GN_70GS]

The -20, -25, -45 are the speed in tens of NS

-20 means 200 NS
-25 means 250 NS
etc.

 

[ijames]

Yes, the other letters are just different manufacturers part numbers. So long as it contains "2732" you are okay. The 2732 is the original chip and needs 25V for programming, while the 2732A came later and only needs 21V (and I think programs a little faster?). That only matters because you have to tell your eprom programmer software which you are using so it can set the voltage correctly. Nowadays about all you find are the 2732A's, and as I said, any speed will work for us. I buy used pulls from a local place and seem to throw away about 10-20% because they won't program after erasure. Could be the chip, could be my Pocket Programmer, but at $1 each the last time I got 20 I don't care toooo much. I have also had maybe two chips that programmed and verified okay but would not work in the car. They just gave the old rapid flashing ses light code 52. Pulled them back out of the car and they still verified okay in the pocket programmer, just before hitting the garbage can . Of course, one had been mailed to someone who had to send it back, sigh.

 

[Dean]

Thanks, folks.


Dean