SO-DIMM and standard ata 2.5 inch drives. For an example: IBM/Hitachi Travelstar 20GB 2.5 inch and bigger, how to do it, see bottom of the story
This story, below is not completly true, there are now 128 mb SO-DIMM's that are small enough to fit in the lower slot.
The Macintosh PowerBook G3 Series computers have two RAM expansion slots that accommodate standard SO (small outline) DIMMs using SDRAM devices. One slot is on the bottom of the system module and is normally occupied by the factory-installed SO-DIMM. The other slot is on the top of the system module and is available for a user-installed SO-DIMM. RAM expansion SO-DIMMs for the Macintosh PowerBook G3 Series computers must use SDRAM devices. If the user installs an SO-DIMM that uses EDO devices, the death chimes will sound when the user attempts to restart the computer.
An SO-DIMM for the Macintosh PowerBook G3 Series computers can contain either 16, 32, 64, or 128 MB of memory. Because of space limitations, a 128 MB SO-DIMM will fit only in the top slot. Total RAM capacity using the highest-density devices available is 192 MB and is limited by the space available for the SO-DIMMs. The bottom slot can accommodate a 1.5-inch SO-DIMM with up to 64 MB of SDRAM. The top slot can accommodate a 2.0-inch SO-DIMM with up to 128 MB of SDRAM.
Note: Future devices with higher density may allow expansion beyond the current 192-MB limit.
Mechanical Design of RAM SO-DIMMs
The RAM expansion modules used in the Macintosh PowerBook G3 Series computers are standard 144-pin 8-byte DRAM SO-DIMMs, as defined in the JEDEC specifications. The mechanical characteristics of the RAM expansion SO-DIMM are given in the JEDEC specification for the 144-pin 8-byte DRAM SO-DIMM. The specification number is JEDEC MO-190; it is available from the Electronics Industry Association's web site, at http://www.eia.org/jedec/download/freestd/pub95/#MO
The specification defines SO-DIMMs with nominal heights of 1.0, 1.25, 1.5, or 2.0 inches. Macintosh PowerBook G3 Series computers can accommodate two SO-DIMMS, one with a height up to 1.5 inches and the other with a height up to 2.0 inches.
Electrical Design of RAM SO-DIMMs
The electrical characteristics of the RAM SO-DIMM are given in section 4.5.6 of the JEDEC Standard 21-C, release 7. The specification is available from the Electronics Industry Association's web site, at http://www.eia.org/jedec/download/freestd/pub21/
The specification defines several attributes of the DIMM, including storage capacity and configuration, connector pin assignments, and electrical loading. The specification supports SO-DIMMs with either one or two banks of memory.
The JEDEC specification for the SO-DIMM defines a Serial Presence Detect (SPD) feature that contains the attributes of the module. SO-DIMMs for use in the Macintosh PowerBook G3 Series computers are required to have the SPD feature. Information about the required values to be stored in the presence detect EEPROM is in section 126.96.36.199 and Figure 4.5.6C (144 Pin SDRAM SODIMM, PD INFORMATION) of the JEDEC standard 21-C specification, release 7.
Because the SO-DIMM connector has only two clock lines, and each clock line is limited to only 4 loads, an SO-DIMM with more than 8 SDRAM devices must have buffers on the clock lines. The buffers must be zero-delay type, such as phase-lock loop (PLL), which regenerates the clock signals. For example, the computer can support a 128-MB SO-DIMM using 16 devices and a PLL clock buffer.
The SDRAM devices used in the RAM expansion modules must be self-refresh type devices for operation from a 3.3-V power supply. The speed of the SDRAM devices must be 100 MHz or greater. 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
The table below shows the sizes of the RAM expansion modules that can be used in the Macintosh PowerBook G3 Series computers and the different sizes of SDRAM devices that make up those modules. Macintosh PowerBook G3 Series computers accept either one or two SO-DIMMs. Any of the supported SO-DIMM sizes may be installed in either slot. The memory controller configures the combined memory of the SO-DIMMs into a contiguous array of memory addresses.
Note: The Macintosh PowerBook G3 Series computers do not support memory interleaving, so installing two SO-DIMMs of the same size does not result in any performance gain.
How can you add memory and change the harddisk, see the pictures below:
To open a G3 Powerbook is a very simple process,
1st remove the battery with the handle
Then remove the cd or when you are lucky the dvd drive
go with your fingers inside the machine and level the keyboard, so you can remove it.
removed keyboard, the plate that protects the memory and cpu and the harddisk are now visible
From this point it is very straight forward, the plate has 2 screws and the harddisk 1. Below my hand is the second screw that holds the plate.
the harddisk screw.
The harddisk is connected to the powerbook with it's own kind of connector, but if you remove that you will see a standard connector.