Re: Help with mystery card ID?

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <3okdvp$8e5@cheyenne.iac.net>,  <Mark Fisher> wrote:

> Yep, that's what you got. The 2708 is most likely an EPROM, so don't
> take that sticker off, it's covering a little window that allows UV
> light to erase the chip's memory! (Maybe not; the "C" may mean CMOS
> which would make it electrically erasable.)

A 2708 is an EPROM (UV erasable).  EEPROMs (electrically erasable)
didn't exist back then.  CMOS has nothing to do with electrical
erasability - it is a manufacturing process which results in different
characteristics such as lower power consumption (compared to NMOS), but
no functional differences.

> The cincher is the 74LS377, though; that's a latch, 
> used to hold the TTL data signals to the printer high until the
> printer has read them. The more common chip used here is the 74LS375,
> which is only slightly different in operation

Hardly.  The '377 is a D-type (triggered) 8-bit latch with an enable
input.

The '375 is a 4-bit D-type (triggered) latch with true and inverted
outputs and separate trigger inputs for each pair of outputs.


By the way: your news posting software is broken.  It didn't include
your E-Mail address in the "From" field (only your personal name).


-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand