Hi,

Quick difference -  how the power supply connects to the main board and is
turned on and off.

ATX is a single block connector as is uATX  - uAtx the board is a specified
small size factor - and turn on and off is thru a relay on the board.  Will
usually have ps/2 or USB mouse and keyboard connectors.  Memory will
usually be 168 pin dimm simms, or DDR or rambus modules

Baby AT is powered by 2 leads from the power supply, usually P8 and P9 where
you have to make sure the black wires are in the center when connected to
the board.  also the power supply is turned on by a mechanical switch
rather than an elecronic relay.  there would be a specfic connection to the
power supply from the front of the case.  The size of the board is what we
are used to the past 10 years.  AT boards used to be twice as big and
needed to be in full towers of huge desktop boxes.  At boards will usually
have the larger AT (din 5) keyboard plug.  Memory was usually 30 pin ( done
in pairs or quads) or 72 pin simms  done in pairs.  Just before ATX became
popular they started introducing 168 pin edo and s-drams to these boards.

The advancement in memory actually lead to the main board getting smaller.
less real estate was needed to hold the memory.  I started back when you
had to put in 18 pcs of ram for a bank - chip by chip and the board would
have 4 rows to populate.  Needed a lot of room - those were the AT boards.

the advanvcement of the power supply from AT to ATX lets us have more
remote control features over our systems than the At power supply offered,
with features like wake on lan, wake on modem, last on power state, etc.




God Bless America!

Joe Lore
MicroComputerCenter, Inc.
781-933-5530 / [log in to unmask]

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