Good Luck! Without documentation it is a pure case of
trial and error. My best 486 boards were:
1. PCI board that accepted either EDO 72 pin,
or FP 72 pin and 30 pin. If I used 30 pin, this was considered
bank 1, so 72 pin slot 1 could only use single sided ram
as bank 0. Single Sided simms are usually 1, 4, 16, and 64 meg.
The other 72 pin slot could use 8 or 32 meg simms as well.
2. VLB board that had the same bank 1 restriction, but allowed
EDO 72's and FP 30's. Not a very good board otherwise, but
this was really nice feature. As all my boards preferred non-parity,
I had no trouble mixing in my parity 30 pins with 72 pin non-parity
simms.
All my other boards required a jumper change to use 30 pin simms.
They also were very picky about what went into 72 pin slot 1.
Some wanted it empty. Others required all 72 pin ram to be single
sided, regardless of the slot. This leads to very restrictive memory
sizes, like two 16 meg 72 pin simms and 4 4meg 30 pin simms for a total
of 48 meg, which cancels out the reason for using the 30 pin simms in the
first place.
After reading Bob's post, I have two more comments. The speed is not
going to be an issue on a 486. If you use 70 or 80 nanosecond 30 pin
simms, they will not effect overall system speed. Next, the 30 pin simms
slots typically have to be filled in groups of 4, not pairs, in this
type of board. All 4 30 pin simms must be of the same size and either all
parity or all non-parity.
If your trying to build a win95 pc, I have had good performance improvements
when bumping a 486 from 12 meg to 16, or a 20 meg (1 16 meg simm and 1 4
meg simm) to 24 meg using 4 1 meg 30 pin simms, particularly becuase mine
were running on a Microsoft windows network. If you have 4 4 meg 30 pin
simms, better still. However, you don't need the ram for win3.1, and I
wouldn't
bother with this if you want to run win98. Two 72 pin 16 meg simms
totalling
32meg is the best configuration on a low budget, especially for Linux, etc.
Tom Turak
-----Original Message-----
From: Mark Rode
Sent: Thursday, May 11, 2000 1:18 PM
I am working on a old 486 board. This was one is probably circa 95-96 and
has a AMD486DX100 in it. There are two 72 pin simms being used and four
30 pin simms slots unused. As I recall dual simm slots and pin adaptors
were pretty common back then so that users did not have to get rid of their
old 30 pin simms.
Does anyone recall if it was common to use both 72 and 30
simultaneously...or were there particular requirements that had to be met?
....or was it depends on the board ? What were the issues ?
thanks
m
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