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.
Memory
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
The SPARCstation 20 has two internal SCA bays, an externalSCSI 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 SCSIhost 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.
Network
The SPARCstation 20 has one integrated AMD Lance10baseTEthernet interface. Additional Ethernet interfaces can be added with an SBus card.
Graphics
The SPARCstation 20 has a built in 13W3 video socket driven by an optional SX framebuffer built onto a VSIMM. The VSIMM is available in 4MB or 8MB capacity, capable of up to 1280x1024 or 1152x900 in 24-bit color. If two VSIMMs are installed an auxiliary video board must also be installed to provide a second 13W3 video socket. Alternatively, SBus cards can be used, including the ZX, Turbo GX and others.
Sound
The SPARCstation 20 has integrated sound with 4 standard 3.5 mm audio jacks for headphones, microphone, line in, and line out.
NVRAM
The SPARCstation 20 uses a battery-backed NVRAM module to hold data about the system, such as the host ID and MAC address. If the battery on the chip dies, then the NVRAM module must be replaced, and the NVRAM must be reprogrammed with a MAC address and host ID. Optionally a M48T08-100PC1 can be used.
117 SPARCstation 20 Model HS11 units, 87 with two 100 MHz hyperSPARC processors and 30 with four 100 MHz hyperSPARC processors, plus a single octo-processor SPARCserver 1000 were used to render Toy Story.
