Try Out The Screen Switching Commands - AMSTRAD cpc 6128 User Instruction

The command:
I S eRE ENS W A P , [<screen section> , J<screen number> , <screen number>
.... exchanges the contents of two blocks, whereas:
I S eRE E NCO P Y , [<screen section> , J<destination screen number> ,
<source screen number>
.... copies the contents of one block into another block.
The optional <screen section> parameter causes the software to copy only 1I64th ofthe
block (256 bytes out of 16K). <screen section> therefore takes values in the range 0 to
63. This mode of operation is useful ifit is required to interleave any other processing
with screen moving. A screen-swap can take around 150/300ths of a second (150
TIME-counts).
The <screen number>s required are 1 (the normal screen), and then either 2,3,4, or 5.
Copy and swap operations where the source or destination is screen 1, will operate
much faster. Be careful of the screen hardware-roll effect, as experienced when
dealing with disc screen dumps. It should be arranged that all the screen images are
constructed (and viewed) with screen 1 set to the same hardware position. The
simplest (default) position is that set by a MOD E command.
Try out the screen switching commands ....
First, run the BANK MANAGER program from Side 1 of your system discs package
by:
RUN "BANKMAN"
Then type:
MOD E 1
Screen clears. Now type:
I
This is the original screen
ISCREENCOPY,3,1 'Send original screen to memory 3
C LS
More About the Bank Manager .... Chapter 8 Page 3