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

CHAPTER 10-SHAPING UP 107as the computer draws off the end of your shape and on into memorygarbage. To save the table currently in memory, type:orBSAVE TABLE1,A$3, L$19BSAVE TABLE1, A768 , L25The only difference between the two is that the first gives the address (A)and length (L) in hex, and the second gives them in decimal. If you add thefollowing lines to Listing 10-1, they will automatically load the table andinform the Apple of its location when the program is run.22 PRINT CHR$(4); "BLOAD TABLEl"24 REM CHR$ (4) IS CTRL-D26 POKE 232,: POKE 233 ,328 REM $ INTO $E8, $3 INTO $E9A longer shape table may not fit at $3(/)(/) since only the range $3©©-$3BF isavailable; a total of 192 bytes. (See the memory map in Chapter 3.) Longtables are often placed up at the top of available memory, and thenHIMEM set underneath them so they will not be overwritten by the variablesof your APPLESOFT program. For a 48K machine, DOS sets HIMEM to$96©© (384©©), so if your shape table was $1 (]')(]') (256) bytes long you wou IdBLOAD [tablename] ,A$95HIMEM : 38144or, in decimal,BLOAD [tablename] , A38144HIMEM : 38144A more thorough discussion of the use of BLOAD and HIMEM can befound in Chapter 7 where we covered saving the Low-Res screen.If you wish to save the table on tape, you must enter the Monitor anduse a variation of the Write command to save the memory range containingthe table. You must know the hex values fo r the fi rst address, the lastaddress, and the length of the table. In the table that contains the saucer,this would be $3©©, $318, and $19, respectively. First, you put the lengthof the table in locations (]') and 1 by typing:: 19 (Remember lo-byte/hi-byte)then write the information onto the tape using the Monitor "W" . Writebytes zero and one onto the tape (they contain the length of the table),and then immediately write the table itself. To do all this in one instruction,you could type:.lW 3 .318W