IBM 5150 - BIOS upgrade on 16KB-64KB motherboard - SW2 example


When upgrading the BIOS on a 16KB-64KB motherboard to the 10/27/82 one, the setting of SW2-5 needs to be changed in most cases.
The following is an example - 128 KB of RAM.

	SW2-1	SW2-2	SW2-3	SW2-4	SW2-5	SW2-6	SW2-7	SW2-8	Comment
04/24/81 BIOS	ON	OFF	ON	ON	OFF	OFF	OFF	OFF	See note 1
10/19/81 BIOS	ON	OFF	ON	ON	OFF	OFF	OFF	OFF	See note 1
10/27/82 BIOS	ON	OFF	ON	ON	ON	OFF	OFF	OFF

Note 1

For the 04/24/81 and 10/19/81 BIOS, IBM instructed that switches 5 to 8 on SW2 be set to off (even though it is a 'do not care' situation). You can see that instruction on the bottom of page 2-28 in the AUG81 edition of the Technical Reference manual.