williams-et-al-1983-apple-ii-computer-graphics

3System Monitor­Memory TricksObjectivesAfter reading Chapter 3 you should be able to:• Enter and leave the Monitor.• Examine RAM and ROM.• Change the contents of RAM.• Move blocks of memory.• Use a memory map to locate reserved and free memory.In essence, your computer is simply a pile of very fancy circuitry, andthose circuits are designed to respond to a certain set of very, very rudimentaryinstructions. Although BASIC will respond to high level commandssuch as NEW and PRINT, those are commands of your language,and not your processor. It is the function of the BASIC interpreter totranslate those statements down to the elementary ones and zeros thatyour processor requires to operate; the machine takes over from there.The capabil ities of BASIC are good as far as they go, but there are applicationsto graphics which req uire that the programmer deal directly withmemory.Memory is where everything happens, and though you can reach memoryusing BASIC's PEEK and POKE statements, there is a faster, morepowerful, and sometimes more convenient method . Supplied in the ROMof every Apple is the system Monitor, with a capital M, which is very13