i know i need a 27C128 but which one should i buy? i am unsure of all the different options. I am going to be using a modified ARAP.bin

thanks
jake

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87 Iroc-Z 305 TPI
Dynomax exhaust
modified MAF & airbox
3-10" JL subs
Eclipse components

 

To date, I haven't seen one that wouldn't work. I just get used *pulls* from surplus places. I wait til a group buy goes down and stock up when the price is right.

You might read up on the 29256s EEPROMs and double load your 128 bin into that.

 

I want to buy a few chips to get started, do they need to be special for 12.5 vDC or what. i see so many different 27c128 chips? i don't want to buy the wrong ones.

[This message has been edited by 87ColdAirIroc-Z (edited June 25, 2001).]

 

EPROM stands for (I believe, correct me if I am wrong) Erasable Programable Read Only Memory.

EEPROM stands for Electronically Erasable Programable Read Onlly Memory.

Examples: 27C128-90, 27C256-90 29C256-90

From what I understand, the 27 determines what kind of chip it is, 27 is E-PROM, 29 is EEPROM, the biggest difference between the 2 is the 27 is UV erased, and the 29 is Electronically erased. The 29 therefore does not need the extra UV eraser to bee re-used.

The C is an unknown, for all as I know it might mean "Chip"

The 128 or 256 is the amount of memory "K" on the chip.
From WHAT I understand, You can usually go from 128 to 256 chips without much of a problem. But DO not go the other way around from a 256 to a 126. There are some issues to be resolved by going from 128-256K, but most of these can be resolved by going through the archives. Do a title only search on 29C256, and you will find out some stuff.

the last numbers EG -50. -70, -90, -128 all represent the speed of the chip, the LOWER the number the Faster the chip, it is a throwback to when that was the case. It represents Nanoseconds access time.
DO NOT get confused with how they are now PC100 & PC133 memory is structured in a completely new way son dont mix em up.

There is a learning curve, so the first little while is a little shakey, AS I AM finding out. But I trust that MOST of these people here on this board are willing to help you out.

Hope this helps


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87 Formula TPI (5 Speed) Yellow/Gray STOCK

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83 Camaro (Parts)
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http://www.3rdgenformula.com

 

When you mention 12.5V, or whatever voltage is specified for the chip, that is the programming voltage. Your only concern here is that your chip programmer will be able to write at the voltage that the EPROM needs. After that, its all TTL level! (i.e. ~0V is low, ~5V is high)

Note that the newer EPROMs seem to program at lower voltages, older ones need a higher programming voltage.

 

Oh, BTW, the "C" stands for CMOS (as opposed to PMOS or NMOS). I don't claim to be a chip fabricator, but the gist of it is that non-CMOS chips require two or more supply voltages to make the thing run. CMOS chips require only a 5VDC supply (not counting the programming voltage of course). Not surprisingly, this makes life a lot easier on the PCB designers!

the "128" or "256" (or whatever) refers to the number of BITS of memory capacity of the chip. The chip is organized into 8-bit words, so you'd have 128/8 = 16K bytes of storage available on the 27128. Double that for the 27256, and so on.

 

BITS, NOT "K" YOUR RIGHT, SORRY, my mistake

John