Memory Bank Layout on the SPARCstation 10SX

There are two memory banks on a SPARCstation 10SX. Bank 0 is comprised of slots 0, 1, 2, and 3. Bank 1 is comprised of slots 4, 5, 6, and 7. These 8 slots are available for configuring memory on the SPARCstation 10SX. Each bank of memory can map 256 MByte of physical address space. Each slot in each memory bank maps 64 MByte of physical address space.

The beginning physical address for bank 0 is 0. For bank 1, it is 0x10000000.

Slots 4 must be configured with a VSIMM; slot 5 may be configured with either a DSIMM or a VSIMM (CG14). The SPARCstation 10SX supports 16 MByte and 64 MByte DSIMMs, and 4 MByte and 8 MByte VSIMMs. Each slot maps 64 MByte of physical address space regardless of the size and type of SIMM that is configured in the slot.

Figure 2-1 Memory Layout on Mother Board of SPARCstation 10SX

The table below illustrates the physical address map of a system configured with 16 MByte DSIMMS in all the slots

Table 2-1 SPARCstation 10SX System Memory Layout 16 MByte DSIMMs only

SIMM Slots	DSIMM Size	Physical Address
Slot 7	16 MByte DSIMM	0x1c000000
Slot 3	16 MByte DSIMM	0xc000000
Slot 6	16 MByte DSIMM	0x18000000
Slot 2	16 MByte DSIMM	0x8000000
Slot 5	16 MByte DSIMM	0x14000000
Slot 1	16 MByte DSIMM	0x4000000
Slot 4	16 MByte DSIMM	0x10000000
Slot 0	16 MByte DSIMM	0x0

Table 2-2 below illustrates the physical address map of a system configured with one 4 MByte VSIMM installed in slot 4 and 16 MByte DSIMMs in the remaining slots.

Table 2-2 SPARCstation 10SX System Memory Layout One 4 MByte VSIMM, Seven 16 MByte DSIMMs

SIMM Slots	DSIMM/VSIMM Size	Physical Address
Slot 7	16 MByte DSIMM	0x1c000000
Slot 3	16 MByte DSIMM	0xc000000
Slot 6	16 MByte DSIMM	0x18000000
Slot 2	16 MByte DSIMM	0x8000000
Slot 5	16 MByte DSIMM	0x14000000
Slot 1	16 MByte DSIMM	0x4000000
Slot 4	4 MByte VSIMM	0xf0000000
Slot 0	16 MByte DSIMM	0x0

Thus, on systems configured with 16 MByte DSIMMS, the maximum size of a physically contiguous block of DRAM is 16 MByte. However, you can reserve multiple blocks of SXDRAM on such systems. In order to be able to configure a single block of SXDRAM greater than 16 MByte, the system must be configured with 64 MByte DSIMMs.

Table 2-3 illustrates a system configured with one 4 MByte VSIMM and seven 64 MByte DSIMMs.

Table 2-3 SPARCstation 10SX System Memory Layout One 4 MByte VSIMM, Seven 64 MByte DSIMMs

SIMM Slots	DSIMM/VSIMM Size	Physical Address
Slot 7	64 MByte DSIMM	0x1c000000
Slot 3	64 MByte DSIMM	0xc000000
Slot 6	64 MByte DSIMM	0x18000000
Slot 2	64 MByte DSIMM	0x8000000
Slot 5	64 MByte DSIMM	0x14000000
Slot 1	64 MByte DSIMM	0x4000000
Slot 4	4 MByte VSIMM	0xf0000000
Slot 0	64 MByte DSIMM	0x0

This layout results in one contiguous block of 256 MBytes (slots 0, 1, 2, and 3) beginning at physical address 0, and another block of 192 MBytes (slots 4, 5, 6, and 7) beginning at physical address 0x14000000. Therefore, the maximum amount of DRAM that can be installed in this configuration is 448 MBytes.

A typical system will most likely have 16 MByte and 64 MByte DSIMMs, and VSIMMs. There are a large number of possible permutations of the system configuration which, due to space limitations, will not be discussed here.

To be able to allocate the largest possible block of SXDRAM with a given set of VSIMMs and DSIMMs, use the illustrations in this section as a guide.

The next section provides some information unique to the SPARCstation 20. The two sections following that discuss system software constraints and configuration recommendations that involve both systems.