histcomp:apple_ii

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histcomp:apple_ii [2024-09-24 19:01] – asdfhistcomp:apple_ii [2024-10-01 06:15] (current) – asdf
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     LDA $100,X   ; get high byte of return address     LDA $100,X   ; get high byte of return address
     RTS     RTS
 +</code>
 +
 +==== Writing bytes as hexadecimal ====
 +We don't have to reinvent the wheel for this one --- the [[#system monitor]] includes a handy routine called ''PRBYTE'' (\$FDDA) for just this task, shown below [(a2eenhpg)]:
 +
 +<code asm6502>
 +PRBYTE:    PHA
 +           LSR A
 +           LSR A
 +           LSR A
 +           LSR A
 +           JSR PRHEXZ    ; =$FDE5
 +           PLA
 +PRHEX:     AND #$0F
 +PRHEXZ:    ORA #$B0
 +           CMP #$BA
 +           BCC COUT      ; =$FDED 
 +           ADC #$06
 +COUT:      JMP (CSWL)    ; =$0036, user output routine
 +</code>
 +
 +To make use of it from Applesoft, load the following anywhere into memory:
 +
 +<code asm6502>
 +JSR $DEBE      ; CHKCOM - skips comma in Applesoft parsing
 +JSR $DFE3      ; GETPNT - get pointer to variable data, put it in $83...$84
 +LDY #$00
 +LDA ($83),Y    ; get high byte from VARPNT
 +JSR $FDDA      ; PRBYTE
 +INY
 +LDA ($83),Y    ; get low byte from VARPNT
 +JMP $FDDA      ; PRBYTE (will RTS for us)
 +</code>
 +
 +Then it can be called from Applesoft like so (assuming the program was loaded at \$0300):
 +
 +<code basic>
 +10 LET X% = 69
 +20 CALL 768,X%
 +</code>
 +
 +==== Generate the Mandelbrot set ====
 +Useful as a benchmark. The computer must be in 80-column mode for it to display properly.
 +
 +<code basic>
 +10 FOR Y=-12 TO 12
 +20 FOR X=-39 TO 39
 +30 CA=X*0.0458
 +40 CB=Y*.08333
 +50 A=CA
 +60 B=CB
 +70 FOR I = 0 TO 15
 +80 T=A*A-B*B+CA
 +90 B=2*A*B+CB
 +100 A=T
 +110 IF(A*A+B*B)>4 GOTO 200
 +120 NEXT I
 +130 PRINT " ";
 +140 GOTO 210
 +200 IF I>9 THEN I=I+7
 +205 PRINT CHR$(48+I);
 +210 NEXT X
 +220 PRINT
 +230 NEXT Y
 </code> </code>
  
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 [(a2etechrefmanual>[[https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Computers/Apple%20II/Apple%20IIe/Manuals/Apple%20IIe%20Technical%20Reference%20Manual.pdf|Apple IIe Technical Reference Manual]])] [(a2etechrefmanual>[[https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Computers/Apple%20II/Apple%20IIe/Manuals/Apple%20IIe%20Technical%20Reference%20Manual.pdf|Apple IIe Technical Reference Manual]])]
 [(msc80scschem>https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Interface%20Cards/Z80%20Cards/Microsoft%20SoftCard/Schematics/)] [(msc80scschem>https://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Interface%20Cards/Z80%20Cards/Microsoft%20SoftCard/Schematics/)]
 +[(a2eenhpg>[[https://ia804504.us.archive.org/19/items/about-your-enhanced-apple-iie-programmers-guide/About%20Your%20Enhanced%20Apple%20IIe%20Programmer%27s%20Guide.pdf|About Your Enhanced Apple IIe: Programmer's Guide]])]
 +[(Sather1985>[[https://ia800702.us.archive.org/18/items/Understanding_the_Apple_IIe/Understanding_the_Apple_IIe.pdf|Understanding the Apple IIe]] (1985))]
 +[(usingprodos>[[https://mirrors.apple2.org.za/ftp.apple.asimov.net/documentation/os/prodos/Using%20ProDOS%20-%20The%20Multilayered%20DOS.pdf|Using ProDOS]])]
 +[(allpinoutsa2>[[https://allpinouts.org/pinouts/connectors/buses/apple-ii-slot/]])]
  
 ~~REFNOTES~~ ~~REFNOTES~~
  • histcomp/apple_ii.1727204493.txt.gz
  • Last modified: 2024-09-24 19:01
  • by asdf