Note that, unlike the RISC OS Display Manager, spaces aren’t allowed, and currently neither are the optional eigen and refresh values. Here are the strings used to represent the different colour depths: 

BitsPerPixel	Palette	Colours	String
4	Fixed	16	c16
8	Fixed	256	c256
8	Definable	256	c256p
16	Fixed	32 thousand	c32K
32	Fixed	16 million	c16M

for example: 

x640y480c16M 

On pre-Risc PC Acorn computers you just specify a mode number. If you have extra hardware (such as a colour card) fitted then you can specify the extra modes supplied by this hardware. 

Some example modes: 
 
 

Modes	Resolution	Colours	Memory needed	Memory recommended
12	640x256	16	80K	256K
15	640x256	256	160K	256K
27	640x480	16	150K	256K
28	640x480	256	300K	400K

 

1. Change to it on the desktop.
2. Use the Task Manager to display the Screen Memory value.

• You can allocate more than is needed for the specified mode. The extra is used to speed up blitting, by keeping the data in ARM memory. Blitting happens when the screen is repainted on removing a dialog box or menu in Windows. For small modes (640¥480) then up to 60% extra is useful. For bigger modes less is needed, down to about 15% for big modes  (1280¥1024). The percentage decreases because a typical dialogue box takes up less screen area in a bigger screen mode. The !PCConfig application suggests 25% extra by default, and will not let you enter less than the minimum necessary.

 
• The UseWindowFE advanced configuration option (Allow desktop operation in !PCConfig) must be switched on if it appears, otherwise the Windows driver cannot claim this first 256K video area and thus cannot operate. You will get a Windows driver needs at least nnnK error if UseWindowFE is turned OFF, no matter what value is given for VideoRAM.