Intel 460GX Dimm Types, Minimum/Maximum Memory Size per Configuration, Double Number Memory Size

Memory Subsystem

Figure 5-2for an illustration. In theory all 4 of these lines could be transferring data at the same time. It would then be muxed by the MDC to the SDC and then by the SDC to the bus. This allows data to be moved with no dead cycles on consecutive reads. Another possibility is that the data from cardA is going to the system bus, while the data from cardB is going to a PCI port. Since each memory interface can support the transfer rate of 266 MT/s, data transfers to PCI are completely overlapping transfers to the system bus such that there are no holes in the data traffic.

Table 5-2gives a summary of the characteristics of memory configurations supported by the 460GX chipset.

Table 5-2. Minimum/Maximum Memory Size per Configuration

	DRAM		DIMM	Double	Number of	Memory Size
				Sided?	Chips/
Technology & Configuration			Size
				(Yes/no)	DIMM	Min	Max
16 Mb		2M x 8	2M x 72	No	9	64 MB	1 GB
		2M x 8	2Mx72x2	Yes	18	128 MB	2 GB
		4M x 4	4M x 72	No	18	128 MB	2 GB
		4M x 4	4M x 72 x 2	Yes	36	256 MB	4 GB
64 Mb		8M x 8	8M x 72	No	9	256 MB	4 GB
		8M x 8	8M x 72 x 2	Yes	18	512 MB	8 GB
		16M x 4	16M x 72	No	18	512 MB	8 GB
		16M x 4	16M x 72 x 2	Yes	36	1 GB	16 GB
128Mb		16M x 8	16M x 72	No	9	512 MB	8GB
		16M x 8	16M x 72 x 2	Yes	18	1 GB	16 GB
		32M x 4	32M x 72	No	18	1 GB	16 GB
		32M x 4	32M x 72 x 2	Yes	36	2 GB	32 GB
256 Mb		32M x 8	32M x 72	No	9	1 GB	16 GB
		32M x 8	32M x 72 x 2	Yes	18	2 GB	32 GB
		64M x 4	64Mx72	No	18	2 GB	32 GB
		64M x 4	64M x72 x 2	Yes	36	4 GB	64 GB

5.1.1DIMM Types

The 460GX will support PC-100 DIMM’s that meet the requirements defined in Table 5-3.

The only DIMMs supported are 3.3 volt 168 pin (x72) parts. These may be composed of 16Mb, 64Mb or 256Mb DRAMs. The 256Mb DRAMs must have a supply voltage of 3.3 volts.

The DIMMs used must have the serial presence detect (SPD) feature, since this is used to program the chipset configuration registers. DIMMs not having SPD will be considered as not-present in the system, since they are not visible to firmware.

DIMMs may have a buffer on the DIMM itself. The buffer can be used in a registered mode or a pass-through mode. The 460GX will support both buffered and unbuffered DIMMs. It will support the buffered DIMM in the pass-through mode, not the registered mode. Thus the timings of the state machines in the MAC will be the same for both types of DIMM. DIMMs with 36 components will be buffered. DIMMs with 9 or 18 components may be buffered.

Intel® 460GX Chipset Software Developer’s Manual 5-3