Difference between revisions of "AlphaServer DS20e"

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Latest revision as of 06:34, 30 August 2019

The AlphaServer/AlphaStation DS20e is an EV6 family based dual processor system and the final iteration of the DP264 family.

Other members of the family were the Compaq DP264, targeted at OEMs, and the direct pre-decessor, the AlphaServer/AlphaStation DS20.

Common Hardware Specification

Main Logic Board

The mainboard is built around the Tsunami chipset, offers two separate 64bit PCI hoses clocked at 33MHz for a maximum throughput of 266MB/s each. It provides expandability by means of 5 64bit PCI slots and on shared 64bit PCI/ISA slot. Connected to the first hose are

  • the three of the six 64bit PCI slots which are closest to the memory slots
  • a Adaptec AIC-7895 dual-channel Ultra-Wide SCSI controller
  • the Cypress Multifunction Controller, providing
    • two IDE channels
    • the PCI-ISA bridge
    • a floppy controller
    • two serial ports
    • one parallel port

The second PCI hose takes care of the remaining three PCI slots.

The mainboard has two CPU slots and 16 memory slots, which are organized in four banks of four slots for a maximum memory throughput of 2.6GB/s. Two consecutive banks filled with 8 identical modules enable memory interleaving for twice the throughput (5.2GB/s).

The memory banks are laid out as follows:

1-3-1-3-0-2-0-2 [CPU1] [CPU0] 2-0-2-0-3-1-3-1

Memory banks need to be populated one after another, each consisting of four identical modules.

Maximum supported memory size per module is 256MB 200pin PC100-ECC-R SD-RAM for a system's total of 4GB.



The DS20e was available as either a 5U rack mountable system or - with additional case skins - as a tower system.


The DS20e supports one or two of the following CPU modules:

  • KN310[AA|AB|AC] - 500MHz EV6, 4MB Cache
  • KN311[BA|BB|BC] - 667MHz EV67, 8MB DDR-Cache
  • KN312[BA|BB|BC] - 833MHz EV68, 8MB DDR-Cache

Disk Drives

The DS20e contains an internal StorageWorks drive bay which is available for either 4x1.6" or 6x1.0" SCA drives. SCSI IDs are set automatically (0-6 from bottom to top for the rack mountable or right to left for the tower system).

A slimline CD-ROM/3.5" Floppy combo drive takes care of media exchange and an additional half height 5.25" external drive bay provides room for a tape drive or an additional optical drive.


Power is provided two or three 375W proprietary hot-swappable power supply units (DH-57AAA), while only the latter combination provides N+1 redundancy (operation with only one power supply will be aborted by the internal Server Feature Module (SFM) after a short period of time).


The SFM also provides a remote management console, which allows to monitor the system status, vitals and lets the operator power the system on and off without physical access, among other things.

It can be accessed by connecting to the first serial interface to a terminal/terminal emulator set to 9600,8n1 and typing ^[^[rmc.


The DS20e has two hot-swappable, regulated 120mm fans at the back of the case. In the event of the failure of one of the two fans, the good fan will work at full power. Should both fans fail, the system will shut down.

Additionally, each one of the CPU daughter boards has a dedicated fan on the CPU heatsink.



The DS20 was the predecessor of the DS20e and much more massive than the latter. While the rack-mountable DS20e was only 5U high, the rack-mountable DS20 took up 11U.

The internal layout of the DS20 basically consists of two areas: The mainboard was located vertically on the left side, with one 5,25" drive bay at the top and two 3.5" bays right underneath. The right side contained up to two power supplies at the back of the case, an internal BA365-like StorageWorks shelf and another 5.25" drive bay.


Due to an older board revision, the only supported CPUs were the KN310 and KN311.

Disk Drives

  • StorageWorks disk shelf for up to seven 1.6" SCA drives, optionally configurable for two separate UW-SCSI buses
  • two externally accessible 5.25" drive bays
  • two externally accessible 3.5" drive bays


Power is provided by at least one 720W power supply (P/N 30-48043-01). For redundancy, the DS20 has room for a second power supply.


The AlphaPC DP264 was targeted at OEMs wishing to provide an expansible, high performance Alpha based solution at a relatively low cost.

The major internal differences to the Compaq manufactured systems DS20 and DS20e are the CPUs, a missing SFM and the lack of OpenVMS support due to a different firmware.

The following CPU modules were available:

  • 500MHz EV6, 2MB Cache
  • 667MHz EV67, 4MB Cache
  • 833MHz EV68, 8MB Cache

DP264 based systems required a proprietary case since the mainboard is not ATX compatible. Featurewise, most systems were similar to the DS20e (multiple power supply units, rack mountable), albeit every OEM was free to extend the specs to his likings.