#### Standard resolution (Layers 0 and 1,1) The attribute data comes first, stored as *h* consecutive rows of attributes, *w* bytes wide. Following this is the screen data, stored as *h* × *8* consecutive rows of pixel data, *w* bytes wide. The total memory used is therefore **w × h × 9** bytes. #### HiRes (Layer 1,2) In this mode, each character position is 16 pixels wide, comprising a left and right "half". The screen data is stored as *h* × 8 consecutive pixel rows of data. For each row, the first *w* bytes comprise the left halves of all characters. The next *w* bytes in the row comprise the right halves of all the characters. The total memory used is therefore **w × h × 16** bytes. #### HiColour (Layer 1,3) The screen data is stored as *h* × *8* consecutive pixel rows of data. For each row, the first *w* bytes comprise the pixel data. The next *w* bytes in the row comprise the attribute data. The total memory used is therefore **w × h × 16** bytes. #### LoRes (Layer 1,0), Layer 2 standard The data is stored as *h* × *8* consecutive pixel rows of data. For each row, there are *w* × *8* bytes, with each byte representing a single pixel. The total memory used is therefore **w × h** × **64** bytes. In the previous section, we dealt with bank management. The following command could very well belong there, but since it deals with memory management of the graphics subsystem and specifically with *Layer 2*, we will cover it here. **LAYER BANK** redefines which banks will store Layer 2 display data (the *front buffer*) and which will act as the *back buffer* (for rendering). The syntax is as follows: **LAYER BANK** *n,m* where *n* is the front buffer base bank number for *Layer 2* (this also sets *n+1* and *n+2*) and *m* is the back buffer base bank number (and also sets *m+1* and *m+2*). These values can be the same and both default to **9**. Unlike other **LAYER** commands, it can be executed in any mode. For example to move *Layer 2* to banks **13** to **15** (front buffer) and **16** to **18** (back buffer): ``` LAYER BANK 13,16 ``` If we now give: ``` BANK 9 CLEAR ``` We can see that bank **9** (the original base bank for *Layer 2*) can now be released. The effects of **LAYER BANK** can be undone either by reversing the command, with **NEW** or with **LAYER CLEAR**. Memory banks are also ideal to store palette information as palettes are basically a series of 256 bytes or words (depending on your **PALETTE DIM** setting). There are two commands for that: **LAYER PALETTE BANK** and **SPRITE PALETTE BANK**. Their syntax is virtually identical and is as follows: **LAYER**|**SPRITE PALETTE** *n* **BANK** *b,offset* where *n* is the palette number (**0** or **1**), *b* is the bank number and *offset* is the start location in the bank where the palette values are located. As mentioned above, if **PALETTE DIM** was set to **8**, **LAYER** and **SPRITE PALETTE BANK** will load **256** bytes from bank *b*, *offset*, while if **PALETTE DIM** was set to **9**, **512** bytes will be loaded.