Technically speaking, *Layer 1,1* is the same as *Layer 0* with extra colour capabilities however *NextBASIC* treats them differently to maintain a consistent way of addressing the extra capabilities of the ZX Spectrum Next's *EnhancedULA*. The legacy coordinate system we discussed above applies only on *Layer 0*, whereas *Layers 1* and *2* use the new system. There are three major differences between *Layer 0* and *Layers 1* and *2* as far as character positioning goes. There are more differences but we will examine these in turn in the special graphics *Chapters 15 – 17*. These are: 1. *Layer 0* is organised in a strict 32 columns by 24 rows matrix while the rest can both position characters on a similar matrix (according to character size), or, if so desired, anywhere along the *y* and *x* axes. 2. The user cannot –normally– position characters on the two bottom rows of the *Layer 0* screen while this is possible in the other *layers*. 3. *Layer 0* pixel coordinates begin at the bottom left corner and extend up and to the right while for the rest of the *layers*, pixel coordinates begin at the top left corner and extend down and to the right. This particular difference is not important for character placement on *Layer 0* but it is for the rest of the *layers* and definitely, as we are going to see further down this manual, extremely important for positioning graphics. ### Changing the size of characters With the exception of *Layer 0*, which has, as we mentioned, a rigid organisation of character positions on screen in a 32 x 24 character matrix, all other *layers* have the ability to position characters either rigidly as above (ie. in a *rows* x *columns* matrix) or freely according to *pixel position* of each character matrix's top left corner. Character size can be modified horizontally with the following sequence: ``` PRINT CHR$ 30; CHR$ n; ``` where *n* can be a number from *3* to *8*, which sets the width of all characters displayed on screen from a minimum of **3** to a maximum of **8** pixels wide. Character size is modified vertically by issuing: ``` PRINT CHR$ 29; CHR$ n; ``` where *n* can be a number from *0* to *3*, which sets the height of all characters displayed on screen to the following predetermined heights in pixels: | Value of *n* | Size (pixels) | Description | | --- | --- | --- | | 0 | 8 | Normal Size | | 1 | 16 | Double Size | | 2 | 6 | Reduced Size | | 3 | 12 | Double Reduced Size | These sequences which are more appropriately called *control codes*, are character size shortcuts for *text windows*. These can also be used on *Layer 0* but you would need to *open a window* first when in that mode. The rest of the *layers* have predefined and pre-opened *full-screen text windows* and therefore these *control codes* work there by default. We will discuss *text windows* at length in *Chapter 20 – Channels, Streams and Windows* so for now keep these two *control codes* in mind as only working outside *Layer 0*. They are extremely important to know, as they modify the behaviour of the **AT** and **TAB** modifiers we will examine below. ### Using AT to print to a certain location You have already seen **PRINT** used quite a lot, so you will have a rough idea of how it is used. Expressions whose values are printed are called *PRINT items*, and they are separated by commas, semicolons and apostrophes, which are called *PRINT separators*. A *PRINT item* can also be nothing at all, which is a way of explaining what happens when you