Home

IBM 5170  -  RAM Information


0 KB to 640 KB

Commonly known as conventional memory.
In IBM 5170 documentation and software, IBM refers to this as 'base' memory.
The 5170 motherboard can be fitted with a maximum of 512 KB of conventional memory.  Click here for information on the RAM chips and RAM banks used on the various types of 5170 motherboard.
If conventional memory between 512 KB and 640 KB is desired, it can only be provided by way of an expansion card.


640 KB to 1 MB

Refer to the diagram here.


1 MB to 16 MB

Commonly known as extended memory.
In IBM 5170 documentation and software, IBM refers to this as 'expansion' memory. Do not confuse 'expansion' with 'expanded'.
In an IBM 5170, conventional memory does NOT have to be at the 640 KB maximim before extended memory is added.
Rules: Extended memory must start at the 1 MB address, and be contiguous (no gaps).
For example, if you have three 2 MB extended memory cards, the cards would be configured as follows:
         CARD #1: Address 1 MB to 3 MB
         CARD #2: Address 3 MB to 5 MB
         CARD #3: Address 5 MB to 7 MB
If you break any of the two rules, the 5162 will not 'find' all of your RAM.
Click here to see an example of a 4MB Intel InBoard card (providing 2 banks of 2 MB).
Click here to see some possible uses of extended memory in the 5170.
Click here to see discussion on a possible limitation on the amount of extended memory that can be added.


RAM Count during POST

During the 5170's POST (power on self test), a RAM count is displayed on-screen.
The count shown is the RAM amount, not the RAM address. Click here to see an example.

Note that any expanded memory is not detected, nor checked, by the POST.