TURBOchannel

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A DEC 3000 Model 600 AXP. TURBOchannel slots (with cards installed) are visible in the top right quadrant.

TURBOchannel is a proprietary computer bus used by DEC in most of the MIPS-based DECstation line, some of the later VAXstations, and some early DEC Alpha-based systems. DEC abandoned the use of TURBOchannel in favor of the PCI bus in the mid-1990s.

TURBOchannel is a 32-bit address and data multiplexed bus, clocked at frequencies between 12.5 to 25 MHz, with a maximum theoretical usable bandwidth of 90 MB/s. The bus however differs from others at the time by having point to point control lines. The firmware contained within TURBOchannel cards is MIPS machine code, a remnant of the bus' original use in MIPS-based systems. Because of this, later systems that used this bus such as the Alpha-based DEC 3000 AXP used an emulator contained in its system firmware to properly initialize them.

TURBOchannel is an example of a typical proprietary local bus of the late 1980s and early 1990s, and it shared many similarities with other proprietary local buses, such as Sun Microsystems' SBus and IBM's Micro Channel architecture.