Upgrading the Palm IIIe/IIIx

Background

The Palm IIIe and Palm IIIx have identical system boards in them, but different chips are used to populate the boards. The differences come from three sources. First, the IIIe only has 2M of memory (one 2M DRAM memory chip), while the IIIx has 4M (2 2M DRAM chips). Second, the IIIe uses mask ROM memory, while the IIIx uses Flash ROM memory. Third, the IIIx has a expansion socket, while the IIIe does not. For each of these differences, there are also differences in the support components. For example, there is circuitry on the IIIx board that disables the on-board memory when an expansion card is inserted into the expansion socket. These components aren't required on the IIIe.

One notable fact on this 'common' system board is that is can accept two DRAM memory chips. The IIIe only has one chip, while the IIIx has two 2M chips. The 8M DRAM chips created by the manufacturers have only slight differences from the 2M ones. Fortunately, the system board has been designed to easily accept these 8M chips. The CPU has a built-in memory controller that is capable of managing up to 8M of memory. As a result, it's possible to upgrade the IIIe and IIIx to 8M of memory by modifying the system board.

WARNING

Modifying your device will void the warranty provided by the manufacturer!

Upgrading the IIIe to 4M

There are two changes required.

  • Add a second 2M DRAM chip to the board. This should be an EDO DRAM 60ns chip.
  • Add a jumper at R39 (located just to the right of the top-right corner of the lower DRAM chip in the image below)
At the right is an image of a completed IIIe 4M upgrade

Upgrading the IIIx (or IIIe) to 8M

There are two different 4M configurations used in the IIIx. There are probably two configurations for the IIIe too, although I haven't heard of both. Whatever the case, your final board should look like the one at the right.

  • If you have a IIIe, or a IIIx that has a jumper at R24, then there are 5 steps required:
    (In this case, your 2M chip is a 1K refresh chip such as a Samsung KM416V1204)
    • Remove the existing DRAM chip(s) (U4 on the IIIe, U4 and U5 on the IIIx)
    • Install an 8M EDO DRAM chip in U4 (the one nearest the edge of the board). See below for part numbers
    • Add a jumper at R64 (R64 is at the bottom of the image, between the two small chips labelled B4 and E-4).
    • Move the jumper at R24 to R30 (R24/R30 are just to the right of the empty DRAM socket)
    • Move the jumper at R13 to R14 (R13/R14 are below R24/R30)
  • If you have a IIIx with a jumper at R30, then there are 4 steps required (thanks to Stephane Boudin for this information!):
    (In this case, your 2M chip is a 4K refresh chip, such as a Samsung KM416V1004, LG Semi GM71VS16160, or HY51V16160CSLTC)
    • Remove the existing DRAM chips at U4 and U5
    • Install an 8M EDO DRAM chip in U4 (the one nearest the edge of the board). See below for part numbers.
    • Move jumper R55 to R64
    • Move jumper R56 to R54
At right is a IIIx device, after the 8M upgrade (no matter what board you start with, you'll will end up with a board that looks like the one on the right

For a "before" picture of the unmodified IIIx 4M board that has the jumper at R24, click here.
For a "before" picture of the unmodified IIIx 4M board that has the jumper at R30, click here.

Good luck!

Parts

The 8M DRAM chip required should be EDO, 60ns or better speed, 4K refresh, and must have self-refresh capability! Some compatible parts are: