27128 question

[Eric Schumacher]

>From a technical point of view there is a lot of marginal information about
EPROMS being propagated by users on this list. All kinds of things can
"work" in a given situation but usually it not to difficult to follow the
rules of the manufacturers of these parts. Some simple guidelines are: 
1-Almost any type eg C or no C can be used in any application for which the
configuration is correct eg 8Kx8, 16x8, 32Kx8 etc as long as speed of the
chip in nanoseconds (denoted by the dash number) is equal to or exceeds the
speed requirements for the micro processor it is used with.
2- The problem comes in programming these devices. The programming algorithm
and voltage for each chip varies by manufacturer. As processes have matured
the parameters tend to become more similar. Usually EPROM programmer
manufacturers provide this information. It is common to find this info in
downloadable form on their web site.
3- One way to evaluate the quality of an EPROM/programming job is to run
verification in the programmer while the chip is in the presence of a
controlled UV source. The longer ,measured in seconds, the program validates
the better the device.
Lotsa Luck Eric
85 GTI with VR6 power