Embedded systems: SUMIT-ISM Type 2 seeks to unify PC/104 SBC market
The Small Form-factor Special Interest Group (SFF-SIG) introduced a new modular standard for stackable expansion of single-board computers (SBCs) in April of 2008. Known as the Stackable Unified Module Interconnect Technology (SUMIT), it implements a PC/104-like self-stacking bus based on the latest serial bus and interface technologies. The latest advance is SUMIT-ISM Type 2 and its unified embedded module framework (UEMF).
“UEMF provides a flexible framework that supports current and emerging bus and interface technologies for single-board computers, while offering backward compatibility with legacy standards such as PC/104, PCI-104, and PC/104-Plus,” said Rick Lehrbaum, executive vice president of Diamond Systems Corp. “It’s now possible to envision an extremely long lifecycle and broad range of applications extending well beyond the current transition from parallel to serial busses and interfaces.”
Lehrbaum, and Diamond Systems president Jonathan Miller coauthored a whitepaper explaining the approach.
SUMIT defines the electrical and mechanical characteristics of a stackable expansion bus for single-board computers and expansion modules. SUMIT defines two identical 52-pin connectors (“A” and “B”), which together carry up to 6 lanes of PCI Express, four USB 2.0 ports, ExpressCard support, an LPC (low pin count) parallel bus, SPI.uWire and SMBUS/I2C serial buses, and various power and ground lines.
A separate SFF-SIG draft specification defines a SUMIT-based stackable module format that offers backwards compatibility with the PC/104 Consortium’s PC/104 module standard. Initially dubbed “Express104,” the standard is currently known as “SUMIT-ISM” (where “ISM” stands for Industry Standard Module).
Basically, says Lehrbaum, “SUMIT-ISM features PC/104-compatible board outline and mounting-hole pattern, SUMIT’s pair of 52-pin connectors (A and B) near the top edge, and PC/104’s 104-pin connector array near the bottom edge. The result is a compact, self-stacking, embedded computer module format that supports expansion via SUMIT’s PCI Express and other bus signals, along with PC/104’s ISA bus.”
For further details on PC/104-related specifications, visit www.PC104.org .
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