StackableUSB Standard Moves to Adopt ¼-Size and ½-Size Boards

Montrose, CA. . . StackableUSB leads the way for smaller, more capable plug on I/O boards with the introduction of ¼-size and ½-size 104 form factor boards. The current 104 form factor only supports I/O boards of the same size (3.55" x 3.775"). The ¼-size and ½-size StackableUSB I/O boards more closely match the space needed to implement simple I/O onto stackable boards today than the older and larger 104 form factor. This shrinking size is a natural evolution for StackableUSB I/O boards as microcontrollers and I/O chips pack more functionality into smaller packages.

The introduction of ¼-size and ½-size StackableUSB boards also solves the CPU cooling dilemma. The challenge with higher power Pentium-class single board computers (SBC) on the 104 form factor has been providing cooling to the CPU when an I/O board is plugged on top and completely covers the CPU chip, trapping heat and seriously reducing air flow. Extending the CPU board outside the 104 footprint has been one approach that has lead to form factor introductions such as the EPIC™ form factor and EBX™ form factor. Now, however, between the spaced gained with the smaller StackableUSB connector and the greater exposed board space with ½- and ¼-size I/O boards, the 104 form factor becomes more viable for Pentium-class SBCs.

In order to accommodate the smaller StackableUSB form factors, a fifth stabilizing hole has been added to the 104 foot print definition. By including a fifth centrally-positioned hole on the 104 board, smaller StackableUSB I/O boards can be incorporated into a stack to form a structurallysound, full-featured systems. These can be a space saving of nearly ¾ the size of the same system implemented with the traditional 104 form factor boards with a cost savings up to 60% since less parts and physical PCB board are used. Currently Micro/sys offers the USB1700 in the ¼-size board and StackableUSB CPU boards with the fifth stabilizing hole PC/104 definition.