Small Footprint PCs?
Gameface asks: "I am looking for the smallest system I can find, in quantity, for my company. We need thousands of these systems, and I'd like to ask the Slashdot community what they'd recommend. Looking for the tiniest footprint for: Case, Motherboard, CPU, RAM, HDD, Serial Port, (2) 10/100 ports. No video required, no sound, all access will be via console (serial port). No OS, just a bare piece of hardware that I can load the OS onto the HDD. I'd really like to find something with SIMMS so we can upgrade the RAM if we need to. And of course, price is very much an issue. Thanks."
If you are not too concerned about processorperformance, you might want to look at Soekris Technologies' Net4501 or Net4521. It is not very expandable, but seems to fulfill your requirements nicely. More information is at Soekris' website. Other options would be the PC104 series of modules... but you'd have to find your own enclosures.
... but what measures will you be taking in order to stop employees (disgruntled or otherwise) from slipping any spare machines into their lunch boxes and carrying them out?
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I think that will determine your search more than absolute size. Afterall, you could get a webserver the size of a matchbox, but it'd be pretty lousy as a user workstation... If you want really dense servers, check into the "blade" fad. If you want really tiny user workstations, look into Shuttle's line of small and quiet most-everything-is-integrated barebones PCs (they've got pci slots for that extra nic or whatever). And of course there are all kinds of tiny single board computers for industrial applications.
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I think you'd be hard-pressed to find a modern machine that uses SIMMs. And I think you'd be hard-pressed to find a 486 with 2 10/100 ethernet ports on-board as well.
Do you have any idea what you are really looking for?
http://www.soekris.com/
These are great little PC's the boards are about the size of a piece of toast, with the case they are about the size of 2 pieces of toast, they only use 800 milliamps at 12 volt (if I remember right), have no moving parts, serial console and 3 network ports, and a CF slot for the disk. I have been using one with a IBM microdrive and OpenBSD as a border router for about a year now, and it works great.