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

62 APPLE II COMPUTER GRAPHICS37- 85 FF STA DES TH39- AATAX;BEGIN LDA/STA LOOP3A- Bl FC LOOPTOP LDA (SOURCEL) ,Y3C- 91 FE STA (DESTL) ,Y3E- C8INY3F- D F9 BNE LOOPTOP311- CA DEX312- F 7 BEQ STOP314- E6 FD INC SOURCEH316- E6 FF INC DES TH318- 4C AJMP LOOPTOP31B- 6 STOP RTSEND3Listing 7-8. Assembly language subroutine.In essence, this routine takes $4 bytes of memory from the source rangeand copies it into the Low-Res page 1 area.Wrapping UpBy now yow have probably learned more than you ever wanted to knowabout Low-Res graphics, but do not despair, as many of the same conceptswill apply in Hi-Res graphics as wel l. We have shown you how to controlthe individual units of the Text and Low-Res screens, and how to create,save, and recall pictures on the Graphics screen. Each of the varioustechniques discussed has its peculiar advantages and disadvantages-someare faster than others, some use more memory, some require disks, and soforth. It is up to you, the programmer, to choose the method best suited toyour application.VocabularyBLOADBSAVEEditorEXECHIMEMLo-byte/Hi-bytePLOT