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```
 40 BANK 9 COPY TO 111: REM
    first we copy it
 50 PAUSE 0: REM wait for a
    key
 60 BANK 9 ERASE 128:; Erase it with
    value 128 which is by default a
    red colour for Layer 2
 70 PAUSE 0:; wait for a key
 90 BANK 111 COPY TO 9:; restore it
100 PAUSE 0:; wait for a key
110 LAYER 2,0: LAYER 0
```

You can see easily how fast this happens (and how it can be used for a myriad of applications)

### Using BANK with graphics

Over the course of chapters dealing with graphics, we've used a lot of graphics-related commands that involved the use of **BANK**. These are **BANK LAYER**, **LAYER BANK**, **LAYER PALETTE BANK**, **SPRITE PALETTE BANK**, **SPRITE BANK**, **TILE BANK** and **TILE DIM** all benefiting all providing significant speed enhancements both in development and in usage.

We saw above the use of **BANK COPY** to copy data from one bank to another. This includes Layer data as they too are kept in banks and managed by *NextZXOS*. There is however a specially crafted command that does this and more as it adds more options specifically tuned to the requirements of display. Unlike **BANK COPY**, this is designed to update small areas of the screen to facilitate effects and especially animation. The command is **BANK LAYER** and it is used to quickly copy data from a memory bank to the *screen in the current mode*, or vice versa. The syntax is as follows:

**BANK** *n* **LAYER** *x,y,w,h*|*offset* **TO** [*raster_op*] *offset*|*x,y,w,h*

where *n* is the source OR destination bank number, *x* and *y* is the top left character position expressed in character column and row coordinates, *w*, *h* are the width and height again in characters of the area to be *copied from* or *copied to*, *offset* is the starting offset in the bank we'll be copying to or from while *raster_op*, is an optional symbol modifier to **TO** that affects the data being copied *at their destination* (does not affect the source data).

**TO** *raster_op* can be one of the following values:

| | |
|---|---|
| **TO** | Straightforward copy |
| **TO &** | ANDs the copied data onto the destination |
| **TO \|** | ORs the copied data onto the destination |
| **TO ^** | XORs the copied data into the destination |
| **TO ~** | Copies data into the destination unless it is equal to the global transparency colour (default **E3h**); if so, leaves the destination unchanged |

The area of screen copied by **BANK...LAYER** is defined as with Windows in characters. That means that character positions range from **0** to **31** for *x* and **0** to **23** for *y*, for all modes *except LoRes*, where they range from **0** to **15** for *x* and **0** to **11** for *y*.

Data copied from the screen is laid out as follows, depending upon the currently selected layer (see *Chapter 16*):