CHARS system variable (See *Chapter 24 – System Variables*) will point *NextBASIC* to the location of this new character set. ### Character Graphics Mode In the following chapter, we will be introduced to *Layer 3* – the Character Graphics mode; this is a hybrid graphics mode based around the notion of a character *tile,* that is to say an 8 × 8 pixel matrix very much like the ones we explored above with User Defined Graphics with four very crucial differences: - Each character tile can have up to sixteen colours and not only two. - *All* ASCII characters can be defined by tiles giving the user in effect a truly multi-lingual character display. - *Layer 3* displays can be either 80 columns by 32 rows or 40 columns by 32 rows and not only 32 columns by 24 rows as the regular Spectrum display is. - *Layer 3* cannot be accessed from *NextBASIC* (at the time of writing) in the same, straightforward way, other modes/layers are. You will need to write functions and procedures that utilise the **PEEK**, **POKE**, **IN**, **OUT** and **REG** facilities as well as the **BANK** commands at your disposal in order to make use of this powerful mode. *Layer 3* has other uses as well and we will be discussing those in the following 3 chapters. ### Exercises 1. Imagine the space for one symbol divided up into four quarters like a Battenburg cake. Then if each quarter can be either black or white, there are **2 x 2 x 2 x 2=16** possibilities. Find them all in the character set. 2. Run this program: ``` 10 INPUT a 20 PRINT CHR$ a; 30 GO TO 10 ``` If you experiment with it, you'll find that **CHR$ a** is rounded to the nearest whole number; and if **a** is not in the range **0** to **255** then the program stops with error report: **B integer out of range.** 3. Which of these two is the lesser? **"EVIL"**\ **"evil"**