Figure B-3 Vsimm Memory System; Table B-3 Vram Densities - Sun Microsystems SPARCstation 20 Service Manual

VSIMM
Two versions of the SPARCstation 20 VSIMM are available: 4-Mbyte and
8-Mbyte. The maximum available VSIMM memory capacities, based upon possible
memory allocations, are as follows:
One VSIMM with seven DSIMMS: 8 Mbytes
Two VSIMMs with six DSIMMS: 16 Mbytes
The VSIMM contains a memory display interface (MDI) chip, a video buffer chip
(VBC), and a digital-to-analog converter (DAC). There is also pixel clock generation
circuitry on the VSIMM. The SPARCstation 20 uses 60-nanosecond VRAMs on the
VSIMM. VRAM densities are supported by the SMC and are listed in
illustrates the VSIMM memory system.
FIGURE B-3
VRAM Densities
TABLE B-3
VRAM Density
1-Mbit 256K x 4
2-Mbit 256K x 8
SMC
CONTROL
VSIMM Memory System
FIGURE B-3
VRAMs/VSIMM
32
32
DATA [128]
ADDR [11]
VSIMM
DSIMM
DSIMM
DSIMM
DSIMM
DSIMM
DSIMM
DSIMM
Appendix B
TABLE B-3
Capacity Type
4-Mbyte 128-bit VRAM
8-Mbyte 256-bit VRAM
SIMM slot (8)
Functional Description
.
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