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Mark Rode wrote:
I have a Intel 486DX2 66 that I am thinking of putting in it. I know the 33
and 66 run at the same clock speed so any DX33 should be able to run a 66
without any changes....right? This has a CPU board that isn't a Ziff
socket....I haven't replaced one of these yet......how much or a pain are
these to upgrade? Do you just manually pull them out and push them in....or
is there a trick to it?

The 30 pin memory array is the usual 8 slots.....at present there is 1 meg
in each slot. Do all 30 pin setups allow for mixing the groups of
four.....can I leave 4 megs in and replace 4 with 4 meg 30 pin simms or do
some 30 pin boards require particular memory configurations.
Mark
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Hi Mark,
The board should run okay.  All the manuals I have close at hand (4) do not
require jumper changes to insert a DX/2 chip if the bus speed is the same and
the old chip was a DX.  As for the memory, all 4 manuals require the one meg
simms go into the first bank, usually zero, and the four meg simms go into bank
one (or bank two if your board starts with one instead of zero) for a total of 20
meg installed.  Get the memory working first before you pull the cpu.  If it won't
boot with the one meg simms in the low bank, put them in the high bank.
As for matching simms,  I don't bother even matching speeds on these
bargain upgrades.  Make sure your board supports disabling parity, or make
sure all the RAM is parity.  I have mixed 3 chip and eight chip simms
of 60 and 70 nanosecond.  80 nanosecond may also work, but you may have to
insert a wait state in CMOS settings for reads and writes, etc.
This is actually a worthwhile upgrade if the board has 256k of L2 cache.
I have never come across a DX 33 board that did not, but I have seen plenty of
486 SX cpus installed on boards without any L2 cache, just the 8k of internal
cache.  You can see what kind of upgrades these will provide by disabling the
external cache on a more upscale 486 board.  It is a pretty significant performance
hit, so I don't bother upgrading if the cache isn't installed.  Intel 5 volt DX2/66 cpus
are selling for $10 to $15 at ebay (www.ebay.com) and 16 meg worth of 4 four meg
30 pin simms are less than $30, so it fits tight budgets.
Getting the cpu out is not difficult.  I recommend removing the board from the pc
to do this.   The main problem is that the socket does not make a suitable fulcrum
to pry against in order to lift the cpu.  I use a small piece of wood or plastic to keep
between my tool  and the board when I pry against the cpu.  After all, you don't mind
scratching or banging the old cpu, but you don't want to damage the socket.  If your
really clever you might talk a pc shop technician into removing the cpu for you.  It will take
him about 5 seconds, since the board is out of the pc anyway.
Tom Turak