128KB/640KB Memory Expansion Option - Switches 1 to 5

Switches 1 to 5 control the starting address of the 512 KB bank.

Starting address
Setting
1 MB
1=on, 2=on, 3=on, 4=off, 5=on
1.5 MB
1=on, 2=on, 3=on, 4=off, 5=off
2 MB
1=on, 2=on, 3=off, 4=on, 5=on
2.5 MB
1=on, 2=on, 3=off, 4=on, 5=off
3 MB
1=on, 2=on, 3=off, 4=off, 5=on
3.5 MB
1=on, 2=on, 3=off, 4=off, 5=off
4 MB
1=on, 2=off, 3=on, 4=on, 5=on
4.5 MB
1=on, 2=off, 3=on, 4=on, 5=off
5 MB
1=on, 2=off, 3=on, 4=off, 5=on
5.5 MB
1=on, 2=off, 3=on, 4=off, 5=off
6 MB
1=on, 2=off, 3=off, 4=on, 5=on
6.5 MB
1=on, 2=off, 3=off, 4=on, 5=off
7 MB
1=on, 2=off, 3=off, 4=off, 5=on
7.5 MB
1=on, 2=off, 3=off, 4=off, 5=off
8 MB
1=off, 2=on, 3=on, 4=on, 5=on
8.5 MB
1=off, 2=on, 3=on, 4=on, 5=off
9 MB
1=off, 2=on, 3=on, 4=off, 5=on
9.5 MB
1=off, 2=on, 3=on, 4=off, 5=off
10 MB
1=off, 2=on, 3=off, 4=on, 5=on
10.5 MB
1=off, 2=on, 3=off, 4=on, 5=off
11 MB
1=off, 2=on, 3=off, 4=off, 5=on
11.5 MB
1=off, 2=on, 3=off, 4=off, 5=off
12 MB
1=off, 2=off, 3=on, 4=on, 5=on
12.5 MB
1=off, 2=off, 3=on, 4=on, 5=off
13 MB
1=off, 2=off, 3=on, 4=off, 5=on
13.5 MB
1=off, 2=off, 3=on, 4=off, 5=off
14 MB
1=off, 2=off, 3=off, 4=on, 5=on
14.5 MB
1=off, 2=off, 3=off, 4=on, 5=off
15 MB
1=off, 2=off, 3=off, 4=off, 5=on
15.5 MB
1=off, 2=off, 3=off, 4=off, 5=off


How were those calculated ?
It's an inverted binary sequence based on the fact that switches 1 to 5 monitor address lines A23 to A19 respectively.

1. Divide by 0.5 MB
2. Convert result to binary
3. Prefix binary with additional zeroes to make 5 digits
4. Invert it

Example: 6.5 MB --> 13 --> 1101 binary --> 01101 --> 10010 (on/off/off/on/off)