We'll first give an example of what could go wrong (it's fortunately safe as an example) and then we'll take a detour and explain how the memory map itself is organised from a *NextBASIC* perspective before returning to `PEEK`, `POKE` and their variants. Type: ``` 10 POKE 16384,"ABCabc" 20 CLS:a$=PEEK$ (16384,6) 40 PRINT a$ ``` From what we've talked about thus far, the intention of the program is obvious (for now also never mind what line 10 does; we'll discuss it later). First we put the word **ABCabc** into address **16384** of the memory map. Then we try to extract it from the same memory location. **RUN** the program. What do you see? Certainly not **ABCabc** you were expecting. Now modify lines 20 and 30 and replace **16384** with **20000** in both lines and **RUN** the program again. This is perhaps a contrived example but it shows what happens when you try to use memory that is also being used by something else. In this case, address **16384** is where the contents of the display is stored. After placing the string with **POKE** in address **16384**, a **CLS** is executed which clears the display and the stored string at the same time. Here is a trickier example: ``` 10 LAYER 1,2 20 POKE 16384,255 30 POKE 24576,255 40 PRINT AT 1,0;"16384 = "; PEEK 16384 50 PRINT "24576 = "; PEEK 24576 ``` This program selects *Layer 1,2* (*HiRes*) and then creates two solid and adjacent character sized lines into the display via the **POKE** commands in lines 20 and 30. Running the program, the results almost seem correct except the character sized line is only one character wide. The **POKE** to **24576** did not go to the display in bank **5** because *NextBASIC* placed a different memory page in the memory map to cover the last half of bank **5**. Contrast with the following program that does all its **PEEK**s and **POKE**s to bank **5** (the **BANK** commands will be explained in more detail later). As we will see, **PEEK** and **POKE** into a 16K bank, is done using an *offset* into said bank. This means that the "address" range is **0** through **16383**; Banks are only 16K long after all. Bank **5**, which holds the display is normally placed at address **16384** in the memory map. Performing therefore a **POKE** into address **16384** is the same as **POKE** to offset **0** in bank **5**. Likewise address **24576** corresponds to offset **8192** in bank **5**. ``` 10 LAYER 1,2 20 BANK 5 POKE 0,255: 30 BANK 5 POKE 8192,255 40 PRINT AT 1,0;"16384 = ";% BANK 5 PEEK 0 50 PRINT "24576 = ";% BANK 5 PEEK 8192 ``` This time, the **POKE** to **24756** (offset **8192**) does go to bank **5** and you will see the solid line twice as wide as the first program.