Help Identifying RAM Chips

From: Grant Zozman <gzozman_at_escape.ca>
Date: Sun Nov 2 06:48:36 1997

I have two original Compaq Portables, both of which are giving POST
errors when they boot which indicate bad RAM. I have gone through a few
rounds of swapping RAM chips between the machines to identify the bad
chips, but have come up against a potential roadblock.

My problem is that there are a number of different chips used in the
machines. As I don't have any data books on these chips, I am not sure
if the different numbers are simply different manufacturer's numbers for
the same chips, if some of the numbers are simply date codes, or if they
are really different, incompatible chips.

If someone is familiar with these numbers, or can look them up for me, I
would really appreciate it:

Chip #1:
Hitachi
1818-3006
Japan 8332U
HM4864P-3

Chip #2:
NEC
8539PF513
D41256C-15

Chip #3:
Fairchild (I think; has an "F" with a bar above and below it)
MB81256-15
8548 M79 BC

Chip #4:
NEC
8538PF532
D41256C-15

If you could let me know the size of each chip, as well as the width of
the memory, it would help me determine what size of RAM I should be
setting the motherboard DIP switches for. Also, would I be correct in
assuming the "-15" appearing on most of the chips specifies 15ns?

If anyone is familiar with adding RAM to the motherboard on the Compaq,
I would appreciate your input on the following:

The machine has 4 banks of RAM, consisting of 8 chips each, plus 1 chip
for each bank marked "BIT 0". The first two banks of chips (0 & 1) are
soldered, the other two (2 & 3) are socketed.

1) Is the "BIT 0" chip a parity chip?
2) Can RAM be installed in Bank 2 without having to populate Bank 3?

Any help in regards to the above is much appreciated!! Thanks in
advance.
Received on Sun Nov 02 1997 - 06:48:36 GMT