These Disks couldn't be side switched manually.
The older models used only one side (360 KbKB)
Double side (DD) or even High Density were available.
3"1/2
*DD = 720ko720KB*HD : 1,44 MoMB
5"1/4
Nowaday, only HD 3"1/2 disk can be found at good old retailer's.
But or beloved CPC can't understand easily the concept of High Density Disk with 1,44Mo 44MB avalaible...
So you have to cheat : just put some duct-tape (scotch-tape, whatever...) on the HD Hole.
Tada, a proper DD disk with 720 Ko KB if your OS allows it.Or a common 2x180Ko 2x180KB (2x 178Ko 178KB ?) with firmware Loco Basic, if you have a manual side switcher button too of course).
As the magnetic disk is bigger...well the format is bigger too.
It is common to get 720Ko 720KB disk (using the 2 sides, so 80 tracks)
== Software's issues ==
The side switcher and A-B drive's switchers are needed only if you use old software, as most of them couldn't really figure they were loaded from B drivers, or had no such feature as double sided drives.
They were designed for good old 3" drive so the 720Kb 720KB DD external 3"1/2 is not implemented.
But modern software designers can allow this fairly easily.
Orion Prime uses the Double side feature, enabling a simple 720Kb 720KB disk with no manual side switches.
Rick Dangerous 128+ (1.1 addon) seems to allow the game to be loaded from the B drive.
*[[Orion Prime]]
This pure awsomeness even uses a full DD disk's 80 tracks with more than 700Kb 700KB of Data, but you have to have a proper DD disk drive, as some older models may lack this feature...