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IBM 5160 Motherboard:  RAM Refresh


Pre-reading

First, read the description of RAM refreshing for the IBM 5150, at here.


How is RAM refreshing different to the IBM 5150

1. The 5160 motherboard circuitry is slightly different.  See here and here.


2. As for the count of address bits used for refreshing by motherboard RAM chips, it turns out that there is no difference to the 64KB-256KB type of 5150 motherboard:

Motherboard type	Count of address bits presented to motherboard RAM chips	Count of those address bits used for motherboard RAM refresh	Comment
5150 motherboard of type 16KB-64KB	7	7	All 4116 class RAM chips have '128 cycle' (7-bit) refresh
5150 motherboard of type 64KB-256KB	8	7 for 4164 class RAM chips of '128 cycle' refresh 8 for 4164 class RAM chips of '256 cycle' refresh
5160 motherboard of type 64-256KB	9	7 for 4164 class RAM chips of '128 cycle' refresh 8 for 4164 class RAM chips of '256 cycle' refresh
5160 motherboard of type 256-640KB	9	7 for 4164 class RAM chips of '128 cycle' refresh 8 for 4164 class RAM chips of '256 cycle' refresh 8 for 41256 class RAM chips of '256 cycle' refresh