Z80 Assembly 74: Displaying a Full Screen Image (Loading Graphics Data)
The Full Screen Data Load To display a custom image on the Spectrum (e.g., a title screen or game level background), you must copy two large blocks of data from your program’s memory into the Spectrum’s Display File RAM. The Two Blocks: Pixel Data: 6144 bytes of raw $256 \times 192$ pixel information (starts at `4000H′). Attribute Data: 768 bytes of color and flash information (starts at `5800H′). Routine 1: Loading the Pixel Data The Pixel Data is 6144 bytes long. Since the data layout is non-linear (Part 73), you generally copy the data block-by-block. However, if your source data is already arranged in the Spectrum’s non-linear format, you can use the fastest method: `LDIR′. ...