Those Disk Drives are not the original Amstrad standard.
Yet they were far more cheap and are nowadays easier to use.
Especially the 3½" (3"1/2 ?) as those disk are still availlable in some retailers. You can also easily find such drives in any garbage if you properly scavenge old rusty computers.
Those Disk size couldn't be side switched manually. The older models where using only one side (360 Ko ?) By double side (DD) or even High Density where available.
Formats
3"1/2
- DD = 720ko
- HD : 1,44 Mo
5"1/4
- er...I don't remember (editors please ?)
- 1,2 Mo was the maximum...on my old PC...
Beware : HD
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 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 if your OS allows it. Or a common 2x180Ko (2x 178Ko ?) with firmware Loco Basic, if you have a manual side switcher button too of course).
PC users used to do the opposite : file a HD hole on DD disk...this worked well sometimes.
A clever choice
A great advantage at the time (in the 80's) was to get access to CP/M sofware library, as most of those were on such Disk.
Also, the Disk were far cheaper than the exotic 3", but...few CPC users actually got such drives.
Mostly professionnal users...The common snotling Gamer couldn't even dream of this...until nowadays.
As the magnetic disk is bigger...well the format is bigger too. It is common to get 720Ko disk (using the 2 sides, so 80 tracks)
Software's issues
Many Modern CPC users replace their old 3" by an external 3"1/2, often adding a Disk drive A-B / B-A switcher (allowing to use the external disk Drive as if it were the internal one = Drive A) and/or a side switcher to allow to use a 3"1/2 disk like a 3" disk... switching manually the sides as needed by good old 3" disk drives (yet a decent sofware can do it).
The side switcher and A-B drive's switchers are needed only if you use old softwares, as most of them couldn't really figure they were loaded from B drivers, or has no such feature as double sided drives.
They were designed for good old 3" drive so the 720Ko DD extgernal 3"1/2 is not implemented.
But modern softwares designers can allow this fairly more easily.
Orion Prime use the DD feature.
Rick Dangerous 128+ (1.1 addon) seems to allow the game to be loaded from the B drive.
It is to the CPC-scene to design their softwares to include those options, allowing more un-modded drives to be simply used as external B drives with no need to add extra buttons and cable montages on the Amstrad.
As modifying all the software library of the good gay old time seems impractical, yet modern era software have to use this.
Softwares released on 3"1/2 disk
This pure awsomness even use a full DD disk's 80 tracks with more than 700Ko of Data, yet you have to get a proper DD disk Drive, as some older models may lack this feature...
Non 3" CPC disk drives
- Data Media Disc System
- Jasmin AM5D 5 "1/4 floppy drive
- KDS 5¼" Disc Drive (KDS Electronics)
- Vortex Disc Drives (Vortex)
- any scavenged rusty junk may be good enough nowaday, if you have a 664 or 6128...