SPARCstation 20

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SPARCstation 20 front and rear

The SPARCstation 20 (a.k.a. SS20, codename Kodiak) is a discontinued Sun Microsystems workstation based on the SuperSPARC or hyperSPARC CPU. It is the last model in the SPARCstation family of Sun "pizza box" computers, which was superseded by the UltraSPARC design in 1995.


CPU support[edit]

SM71 SPARCstation MBus CPU Module

The SPARCstation 20 has dual 50 MHz MBus ports that allow it to use faster CPUs than the SPARCstation 10. With two dual-CPU modules and updated firmware, the SPARCstation 20 supports a maximum of 4 CPUs. The fastest CPU produced for the SPARCstation 20 is the 200 MHz Ross hyperSPARC.

The PROM in the SPARCstation 20 determines CPU compatibility. Version 2.25r is the last PROM release for the SPARCstation 20.


The SPARCstation 20 has 8 200-pin DSIMM slots, and supports a maximum of 512 MB of memory with 64 MB modules. Memory modules for the SPARCstation 20 are compatible with the SPARCstation 10, Sun Ultra 1, and some other computers in the sun4m and sun4u families, but they are physically incompatible with the SIMM slots found in PC computers.

2 of the 8 SIMM slots are wider than the others and can be used with non-memory peripherals like caching NVSIMM and video VSIMM cards.

Disk drives[edit]

SPARCstation 20 SCSI cradle with drive

The SPARCstation 20 has two internal SCA bays, an external SCSI connector, and two bays for CD-ROM or floppy drives. Earlier revisions of the SPARCstation20 case contain a CD-ROM and floppy bays that are slightly shorter than a standard 3.5" bay and regular devices intended for PC compatible computers do not usually fit. Later revisions of the SPARCstation20 and SPARCstation5 have a narrower slot for the floppy drive so a more-standard CD-ROM can fit.

The SCSI host controller is integrated with the motherboard. The SPARCstation 20 does not support IDE devices.

A limitation in all releases of the OpenBoot PROM for the SPARCstation 20 prevents it from booting from a point on a disk past the 2 gigabyte mark.


The SPARCstation 20 has one integrated AMD Lance 10baseT Ethernet interface. Additional Ethernet interfaces can be added with an SBus card.


The SPARCstation 20 has a built in 13W3 video socket driven by an optional SX (CG14) framebuffer built onto a VSIMM.[1] The VSIMM is available in 4MB or 8MB capacity, capable of up to 1280x1024 (8MB) or 1152x900 (4MB) in 24-bit color. If two VSIMMs are installed an auxiliary video board must also be installed to provide a second 13W3 video socket.[1] Alternatively, SBus cards can be used, including the ZX (Leo), Turbo GX (CG6) and others.


The SPARCstation 20 has integrated sound with 4 standard 3.5 mm audio jacks for headphones, microphone, line in, and line out.


The SPARCstation 20 uses a battery-backed NVRAM module to hold data about the system, such as the host ID (serial number) and MAC address. If the battery on the chip dies, then the NVRAM module must be replaced (or modified to use an external battery), and the NVRAM must be reprogrammed with a MAC address and host ID. Optionally a M48T08-100PC1 can be used.[2][3]

Operating systems[edit]

SunOS 4.1.3_U1B onwards, Solaris 2.3 to 9, Linux (Debian, Gentoo, SuSE 7.0 - 7.3, probably others), MirOS BSD, NetBSD and OpenBSD run on the SPARCstation 20. On certain CPU modules (Sun SuperSPARC only), NeXTSTEP 3.3 and OPENSTEP 4.x also run.

Related computers[edit]

Sun timeline[edit]

Sun BladeSun FireSun FireSun EnterpriseSun Ultra EnterpriseSun Ultra seriesSun Ultra seriesSun Ultra seriesSun Ultra seriesSun Blade (workstation)Sun 386iSun Java WorkstationSun Ultra seriesSPARCstationSun-3Sun-2Sun-1

External links[edit]

Vendor Documentation[edit]


  1. ^ a b "SPARCstation 20 Service Manual" (PDF).
  2. ^
  3. ^