Digital Personal Workstation
The Digital Personal Workstation is a family of entry-level to mid-range workstation computers developed and manufactured by Digital Equipment Corporation (DEC). These workstations are based on the DEC Alpha and Intel Pentium Pro or Pentium II microprocessors. Members of this family could run the Digital UNIX, OpenVMS and Microsoft Windows NT operating systems. The i-Series, based on Pentium Pro, was introduced first, on 23 September 1996.
The Digital Personal Workstation i-Series was based on the Intel Pentium Pro or Pentium II microprocessor and ran Windows NT.
Models included the: 
- 180i - 180 MHz Pentium Pro, introduced on 23 September 1996
- 200i - 200 MHz Pentium Pro, introduced on 23 September 1996
- 200i² - 200 MHz Pentium Pro, introduced on 23 September 1996
- 266i - 266 MHz Pentium II
- 300i - 300 MHz Pentium II
- 350i - 350 MHz Pentium II
- 400i - 400 MHz Pentium II
- 266i+ - 266 MHz Pentium II
- 300i+ - 300 MHz Pentium II
- 333i+ - 333 MHz Pentium II
These workstations supported either one or two microprocessors and used standard Intel chipsets: Pentium Pro models used the Intel 440FX, Pentium II models suffixed with "i" used the Intel 440BX whereas ones suffixed with "i+" used the Intel 440LX. A superscript "2" suffix indicated a dual processor configuration.
The i-Series has four DIMM slots on its main logic board and supported standard unbuffered or registered 100 MHz ECC SDRAM DIMMs. Using unbuffered memory, the i-Series could support 32 to 512 MB of memory, with registered memory, 64 MB to 1 GB was supported. Unbuffered and registered DIMMs could not be mixed in the same system. Unbuffered DIMMs had capacities of 32, 64 and 128 MB, whereas registered DIMMs had capacities of 64, 128 and 256 MB.
The Digital Personal Workstation a-Series, code named "Miata", used the Alpha 21164A microprocessor. Models suffixed with "a" ran Windows NT (with AlphaBIOS) whereas models suffixed with "au" ran Digital UNIX or OpenVMS (with SRM). At COMDEX 1997, the Digital Personal Workstation 500a was a finalist in Byte Magazine's Best of Show award for the best workstation category.
Models included the:
- 433a/433au - 433 MHz Alpha 21164A
- 500a/500au - 500 MHz Alpha 21164A
- 600a/600au - 600 MHz Alpha 21164A
The Alpha microprocessor was socketed in a zero insertion force (ZIF) socket and could be upgraded. These workstations used Digital's 21174 chipset, also known as the "Pyxis" chipset. To increase flexibility and to reduce cost, the L3 cache was optional in these models. If the L3 cache was required, a cache module that contained the SRAMs which implemented the cache would be installed into a cache slot. The cache module had two capacities: 2 or 4 MB.
Two revisions of the Miata motherboard were produced, known as MX5 and MiataGL respectively. The later MiataGL motherboard has a revised Pyxis chipset (which fixes a PCI DMA bug), a different ATA controller, an on-board QLogic 1040 SCSI host adapter, and a USB interface.
The a-Series has a 144-bit memory bus, with 128 bits used for data and 16 bits for ECC. There are three memory banks, each consisting of two DIMM slots, for a total of six DIMM slots, which supports 32 MB to 1.5 GB of memory. The a-Series uses proprietary 72-bit DIMMs with error correcting code (ECC) that are twice as tall as standard DIMMs and contain two rows of SDRAMs per a column instead of one. These DIMMs are installed in identical pairs in order to match the width of the memory bus.
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