Technical information

CHAPTER 4
Expansion Features
RAM Expansion Slots 71
The devices are programmed to operate with a CAS latency of 3. At that CAS
latency, the access time from the clock transition must be 7 ns or less. The burst
length must be at least 4 and the minimum clock delay for back-to-back random
column access cycles must be a latency of 1 clock cycle.
When the computer is in sleep mode, the maximum power-supply current
available for each bank of SDRAM is 6 mA (see the section “RAM SO-DIMM
Electrical Limits”). Developers should specify SDRAM devices with low power
specifications so as to stay within that limit.
Configuration of RAM SO-DIMMs 4
Table 4-6 shows information about the different sizes of SDRAM devices used
in the memory modules. The device configuration column shows three
numbers that characterize each type of device: the number of addresses, the
number of data bits per access, and the number of internal banks. The fourth
column in the table shows the size of each bank of devices, which is based on
the number of internal banks in each device and the number of devices needed
to make up the 8-byte width of the data bus. The last column shows the
memory size of the largest SO-DIMM with that device size that the PowerBook
G3 computer will accommodate.
Table 4-6 Sizes of RAM expansion devices and modules
Device size
Device
configuration
Devices
per bank
Size of
each bank
Size of
SO-DIMM
16 Mbits 2M x 4 x 2 16 32 MB 32 MB
16 Mbits 1M x 8 x 2 8 16 MB 32 MB
16 Mbits 512K x 16 x 2 4 8 MB 32 MB
64 Mbits 8M x 4 x 2 16 128 MB 128 MB
64 Mbits 4M x 4 x 4 16 128 MB 128 MB
64 Mbits 4M x 8 x 2 8 64 MB 128 MB
64 Mbits 2M x 8 x 4 8 64 MB 128 MB
64 Mbits 2M x 16 x 2 4 32 MB 128 MB
64 Mbits 1M x 16 x 4 4 32 MB 128 MB
64 Mbits 1M x 32 x 2 2 16 MB 128 MB