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Apple II comp.sys.apple2.programmer FAQs, Part 1/1

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Archive-name: apple2/programmerfaq/part1
Posting-Frequency: monthly
Last-modified: 2009/12/01

See reader questions & answers on this topic! - Help others by sharing your knowledge
The comp.sys.apple2 Usenet newsgroup Apple II FAQs originate from
the II Computing Apple II site, 1997-2010. 

Apple II Programming
comp.sys.apple2.programmer Frequently Asked Questions rev124 December 2009


001- What programming languages are available for the Apple II? 
002- Where can I find out about Apple II programming? 
003- Where can I get Apple II languages and programming software? 
004- Where can I find PEEKs & POKEs and monitor routine info? 
005- How can I see and edit what's in a Text file? 
006- How do I save a BASIC program in ASCII text form? 
007- Where and how do I get System 6.0.1? 
008- Where can I get Applesoft shape table info and programs? 
009- What Operating System environments does the GS support? 
010- How do I write programs for the Apple Graphics Tablet? 
011- How do I read the joystick on a GS in native mode? 
012- How do I write programs which use the mouse? 
013- Where can I find manuals and other resources for the CP/M OS?
014- How can I view and enter code using the "monitor"? 
015- What memory areas should a user be careful about modifying? 
016- Can I do multi-tasking on a IIgs? or What is GNO/ME?
017- Which Zero Page locations are likely to be in-use?


Csa2 Programmer FAQs 

Feel free to email comments, suggestions, and materials. 

Jeff Hurlburt  (Include "Apple" in the message title.)


001- What programming languages are available for the Apple II? 

Quite a few. Apple Integer BASIC (in-ROM on the first Apple II's), can be loaded into II+ and later models. Applesoft, a floating point BASIC, is in-ROM on all models starting with the II+. Older Apple II's can load-in Applesoft or, via a plug-in board, access it from ROM. 

Then, there is MD BASIC, the BASIC-like MacroSoft from MicroSparc, a beta version of Apple's GS BASIC, and the new (1998) Byte Works GS BASIC! Users who want to speed up their AppleSoft programs can use a BASIC compiler such as TASC or Einstein. 

Other Apple II languages are Apple Fortran, UCSD Pascal, Orca (ByteWorks) Pascal, Kyan Pascal, Terrapin Logo, Apple Logo, two Logos from ByteWorks, Isys Forth, Master Forth, (and many other Forths), Modula2, Aztec C, Orca/C, ... . Hyperstudio and HyperCard let you create stacks. 

To the above you can add several assemblers including Merlin, Orca/M, an assembler from Ninja Force, and the MicroSparc Assembler. 

You can find a comprehensive listing in Larry Virden's "Apple II Programmer's Catalog of Languages and Toolkits" at . 

For Orca manuals and to order the Orca languages see Byte Works products at Syndicomm ( ).

--Rubywand, Jeffrey Iverson, Andrew Roughan, Willi Kusche


002- Where can I find out about Apple II programming? 

All Apple II's come with some version of BASIC installed in-ROM on the motherboard. The original Apple II's have Integer BASIC. Starting with the II+ model, all Apple II's have floating-point Applesoft in-ROM. Owners of early Apple II's can load in Applesoft or plug in a card with Applesoft ROMs. 

All Apple II's include a "monitor" program in ROM. Entering CALL-151 from the BASIC prompt puts you 'in' the monitor. Here you can view and change values in key memory locations and enter machine language routines. 

Besides these built-in languages, many others can be loaded in and used (see previous Q&A). 

There are several good places on the net to find out about programming: 

Apple II and BASIC programming books on-line (mostly English, some French) (in French).

Apple II comp.sys.apple2 newsgroup 
Frequently Asked Questions (FAQs) distributed worldwide via USENET; 
available as html and Text 

Apple II comp.sys.apple2.programmer newsgroup 
Frequently Asked Questions (FAQs) distributed worldwide via USENET; 
available in pure Text and html: 

Apple II DOS and ProDOS mini manual 

Apple II game authoring links 

Apple II Textfiles 

Applesoft BASIC FAQs on 'Another Computer Museum 



GS WorldView 

Terry Allen's Home of the Apple II- manual reprints, programming info 

LandSnail Apple II References- Applesoft, Integer BASIC, DOS 3.3, 
and ProDOS commands with brief descriptions. 

Magazine and on-line 'zine issues and back issues (see Publishers) 

Major Apple II Sites- many Apple II links 

Niel Parker's Home Page- Apple IIgs progamming information 

Paul Schlyter's Apple II Stuff- compilers, S-C assemblers, utilities, 
Assembly Line disks, ... 

Ron Kneusel's 6502 page- 6502 info, assem tutorials, software 

The Fridge- 6502 info, tutorials, assembly language routines 6502 info, tutorials, assembly language routines 

Be sure to keep a look out for Apple II books, charts, software packages, etc. when you visit used book stores, swap meets, school sales, ..., or peruse comp.sys.apple2 marketplace. 

Applesoft BASIC 

The #1 Applesoft information source is the Basic Programming Reference Manual from Apple. Here are some other good Applesoft materials to look for ... 

Apple II User's Guide by Poole, Martin, and Cook 
  Note: Third Edition (Apple II User's Guide for APPLE II Plus and
  APPLE IIe) is completely revised to include ProDOS coverage
Apple II Reference Manual from Apple 
Peeks, Pokes, and monitor routines info (see below) 
DOS & ProDOS books (see below) 

GSoft BASIC (New IIgs BASIC from Byte Works)

Learning to Program in GSoft BASIC by Mike Westerfield (Byte Works) 

Assembly Language and Machine Language Coding 

Machine coding is when you enter 6502 (65816, ...) instructions directly-- as in going to the Apple II monitor (CALL-151) and typing in hexadecimal codes at specific addresses, like 300:A9 7F (instruction to load Accumulator with the value $7F entered at address $300). 

Assembly coding substitutes easy-to-remember text for the numeric codes-- as in LDA#7F to load the Accumulator with the value $7F. Assembly coding is done using assembler software (like Merlin or Orca/M). A major advantage of assembly coding is that routines and other places in your program can be tagged with text labels and referenced this way in your program. The assembler software figures out things like Jump addresses. 

Assembly Lines: The Book by Roger Wagner 
Programming Manual (for 6502 from Mos Technology, 1976) 
What's Where in the Apple II? by William F. Luebbert 
Beagle Bros "Peeks, Pokes, and Pointers" (poster) 
Programming the 65816 Including the 6502, 65C02, and 65802 
   by David Eyes and Ron Lichty 
65816/65802 Assembly Language Programming by Michael Fischer 

Other Languages 

Apple Pascal: a hands-on approach by Luehrmann & Peckham 
Learning to Program in C by Mike Westerfield (Byte Works) 
Learning to Program in Pascal by Mike Westerfield (Byte Works) 
Logo Plus manual from Terrapin 
HyperCard IIGS Script Language Guide (Apple/ Addison-Wesley) 

DOS, ProDOS, and GS/OS 

The DOS Manual from Apple 
Beneath Apple DOS by Worth & Lechner 
Beneath Apple ProDOS by Worth & Lechner 
Supplement to Beneath Apple ProDOS For ProDOS8 (v1.2,1.3)  by Worth & Lechner 
ProDOS Inside and Out by Doms and Weishaar 
ProDOS Technical Reference Manual (Apple/ Addison-Wesley) 
Apple IIGS GS/OS Technical Reference (Apple/ Addison-Wesley) 
Apple IIGS GS/OS Device Driver Reference (Apple/ Addison-Wesley) 
Apple IIGS System 6 User's Reference (Apple/ Addison-Wesley) 
The System 6 Book by Jerry Kindal (Quality Computers) 
Apple IIGS ProDOS 8 Reference (Apple/ Addison-Wesley) 
Apple IIGS ProDOS 16 Reference (Apple/ Addison-Wesley) 
Apple IIGS Toolbox Reference v. 1-3 (Apple/ Addison-Wesley) 
Exploring Apple GS/OS and ProDOS 8 by Gary Little 
Toolbox Programming in C by Mike Westerfield (Byte Works) 
Toolbox Programming in Pascal by Mike Westerfield (Byte Works) 

One of the best ways to learn programming is to find some old game you like and experiment with customizing it. This works especially well for learning Applesoft BASIC and machine language coding. 

If your Apple II is an enhanced //e or later machine, be sure to get Program Writer. It's a vintage Applesoft program editing utility from Beagle which makes writing and debugging BASIC programs much easier. 

For 48k or larger II+, check out Global Program Line Editor: 

--Rubywand, Terence J. Boldt, Tony Cianfaglione, Steve Sanders, Wayne Stewart, Charles T. Turley, Eniknoc 


003- Where can I get Apple II languages and programming software? 

Byte Works ( ) develops the Orca series of Apple II and IIgs languages including Pascal, C, Assembler, and the new IIgs BASIC as well as manuals, learning packages, and other language materials. 

You can find very good collections of Apple II languages and related software on the net: 

Asimov- Apple II programming software and utilities 

Ground- Apple II languages, programming software, and utilities 

GS WorldView- Apple II programming software and utilities 

Ninja Force Downloads- Apple IIgs utilities 

Paul Schlyter's Apple II Stuff- Compilers, S-C assemblers, utilities

Ron's Software Page- Q Forth

So What Software- Apple IIgs programming software 

TFF Enterprises 

Apple II game authoring software links 

More software links 

--Rubywand, Andrew Roughan 


004- I'd like to do some 'serious' Apple II programming. Where can I
     find a information about soft switches (i.e. "PEEKs & POKEs"), 
     monitor routines, and standard names used for these? 

Names shown are assembler "equate" names/labels. In a few cases, more than one label and function is associated with an address. A few soft switches have no established label.

Not all switches are present on all Apple II models. In general, the later the model, the more features and soft switches are available.

Many soft switches can be toggled via a Read or a Write. If only a Read or a Write is indicated, access the switch or indicator using the indicated method.

Soft Switches and Status Indicators

KEYBOARD = $C000 ;keyboard data (latched) (Read)
                 ;Bit 7 is set to indicate a keypress
                 ;is waiting, with the ASCII
                 ;code in bits 6-0.

CLR80STORE=$C000 ;80STORE Off- disable 80-column memory mapping (Write)
SET80STORE=$C001 ;80STORE On- enable 80-column memory mapping (WR-only)

CLRAUXRD = $C002 ;read from main 48K (WR-only)
SETAUXRD = $C003 ;read from aux/alt 48K (WR-only)

CLRAUXWR = $C004 ;write to main 48K (WR-only)
SETAUXWR = $C005 ;write to aux/alt 48K (WR-only)

CLRCXROM = $C006 ;use ROM on cards (WR-only)
SETCXROM = $C007 ;use internal ROM (WR-only)

CLRAUXZP = $C008 ;use main zero page, stack, & LC (WR-only)
SETAUXZP = $C009 ;use alt zero page, stack, & LC (WR-only)

CLRC3ROM = $C00A ;use internal Slot 3 ROM (WR-only)
SETC3ROM = $C00B ;use external Slot 3 ROM (WR-only)

CLR80VID = $C00C ;disable 80-column display mode (WR-only)
SET80VID = $C00D ;enable 80-column display mode (WR-only)

CLRALTCH = $C00E ;use main char set- norm LC, Flash UC (WR-only)
SETALTCH = $C00F ;use alt char set- norm inverse, LC; no Flash (WR-only)

STROBE =   $C010 ;clear bit 7 of keyboard data ($C000)
If read, it also provides an "any key down" flag in bit 7, with
the keycode in the remaining bits. (These features only apply to
the IIe and later machines.)

Bit seven of these Read Status locations is 1 if the condition is true

RDLCBNK2 = $C011 ;reading from LC bank $Dx 2
RDLCRAM =  $C012 ;reading from LC RAM
RDRAMRD =  $C013 ;reading from aux/alt 48K
RDRAMWR =  $C014 ;writing to aux/alt 48K
RDCXROM =  $C015 ;using internal Slot ROM
RDAUXZP =  $C016 ;using Slot zero page, stack, & LC
RDC3ROM =  $C017 ;using external (Slot) C3 ROM
RD80COL =  $C018 ;80STORE is On- using 80-column memory mapping
RDVBLBAR = $C019 ;not VBL (VBL signal low)
RDTEXT =   $C01A ;using text mode
RDMIXED =  $C01B ;using mixed mode
RDPAGE2 =  $C01C ;using text/graphics page2
RDHIRES =  $C01D ;using Hi-res graphics mode
RDALTCH =  $C01E ;using alternate character set
RD80VID =  $C01F ;using 80-column display mode

TAPEOUT =  $C020 ;toggle the cassette output.

SPEAKER =  $C030 ;toggle speaker diaphragm

STROBE =   $C040 ;generate .5 uS low pulse @ Game pin 5
If read, you get one half-microsecond low pulse on the Game I/O
STROBE pin; if write, you get two pulses. (IIe and ][+ only, not
available on the IIgs).

CLRTEXT =  $C050 ;display graphics
SETTEXT =  $C051 ;display text

CLRMIXED = $C052 ;clear mixed mode- enable full graphics
SETMIXED = $C053 ;enable graphics/text mixed mode

PAGE1 =    $C054 ;select text/graphics page1
PAGE2 =    $C055 ;select text/graphics page2
See IIe, IIc, IIgs manual for details on how these switches
affect 80-col bank selection.

CLRHIRES = $C056 ;select Lo-res
SETHIRES = $C057 ;select Hi-res

SETAN0 =   $C058 ;Set annunciator-0 output to 0
CLRAN0 =   $C059 ;Set annunciator-0 output to 1
SETAN1 =   $C05A ;Set annunciator-1 output to 0
CLRAN1 =   $C05B ;Set annunciator-1 output to 1
SETAN2 =   $C05C ;Set annunciator-2 output to 0
CLRAN2 =   $C05D ;Set annunciator-2 output to 1
SETAN3 =   $C05E ;Set annunciator-3 output to 0
SETDHIRES= $C05E ;if IOUDIS Set, turn on double-hires
CLRAN3 =   $C05F ;Set annunciator-3 output to 1
CLRDHIRES= $C05F ;if IOUDIS Set, turn off double-hires
Note: "0" is near 0V, "1" is near 5V.

TAPEIN =   $C060 ;bit 7 = data from cassette on Apple II,
or PB3           ;II+, IIe. On IIgs bit 7 reflects the
                 ;status of Game Port Pushbutton 3--
                 ;closed= 1. (read)

OPNAPPLE = $C061 ;open apple (command) key data (read)
CLSAPPLE = $C062 ;closed apple (option) key data (read)
These are actually the first two game Pushbutton inputs (PB0
and PB1) which are borrowed by the Open Apple and Closed Apple
keys. Bit 7 is set (=1) in these locations if the game switch or
corresponding key is pressed.

PB2 =      $C063 ;game Pushbutton 2 (read)
This input has an option to be connected to the shift key on
the keyboard. (See info on the 'shift key mod'.)

PADDLE0 =  $C064 ;bit 7 = status of pdl-0 timer (read)
PADDLE1 =  $C065 ;bit 7 = status of pdl-1 timer (read)
PADDLE2 =  $C066 ;bit 7 = status of pdl-2 timer (read)
PADDLE3 =  $C067 ;bit 7 = status of pdl-3 timer (read)
PDLTRIG =  $C070 ;trigger paddles
Read this to start paddle countdown, then time the period until
$C064-$C067 bit 7 becomes set to determine the paddle position.
This takes up to three milliseconds if the paddle is at its maximum
extreme (reading of 255 via the standard firmware routine).

SETIOUDIS= $C07E ;enable DHIRES & disable $C058-5F (W)
CLRIOUDIS= $C07E ;disable DHIRES & enable $C058-5F (W)

"Language Card" area Switches
Bank 1 and Bank 2 here are the 4K banks at $D000-$DFFF. The
remaining area from $E000-$FFFF is the same for both
sets of switches.

           $C080 ;LC RAM bank2, Read and WR-protect RAM
ROMIN =    $C081 ;LC RAM bank2, Read ROM instead of RAM,
                 ;two or more successive reads WR-enables RAM
           $C082 ;LC RAM bank2, Read ROM instead of RAM,
                 ;WR-protect RAM
LCBANK2 =  $C083 ;LC RAM bank2, Read RAM
                 ;two or more successive reads WR-enables RAM
           $C088 ;LC RAM bank1, Read and WR-protect RAM
           $C089 ;LC RAM bank1, Read ROM instead of RAM,
                 ;two or more successive reads WR-enables RAM
           $C08A ;LC RAM bank1, Read ROM instead of RAM,
                 ;WR-protect RAM
LCBANK1 =  $C08B ;LC RAM bank1, Read RAM
                 ;two or more successive reads WR-enables RAM
           $C084-$C087 are echoes of $C080-$C083
           $C08C-$C08F are echoes of $C088-$C08B

CLRC8ROM = $CFFF ;disable Slot card C8 ROM
Reading any location from $Cn00-$CnFF (where n is the Slot) will
enable the $C800-$CFFF area for that card, if the card supports
this feature. Reading $CFFF disables this area for all cards.

Example: To enable double Hi-res graphics, the following code will
accomplish this:

JSR $C300, David Empson, Rubywand


The following is a list of PEEKs, POKEs and Pointers in the zero page area. Most of the information comes from the Beagle Bros chart (1982).

FP= "floating point"= Applesoft BASIC   INT= Integer BASIC
Note: Text window and related settings refer to 40-column mode

Decimal | Hexadecimal |
32      | $20         | Text window left-edge (0-39)
33      | $21         | Text window width (1-40)
34      | $22         | Text window top-edge (0-23)
35      | $23         | Text window bottom (1-24)
36      | $24         | Horizontal cursor-position (0-39)
37      | $25         | Vertical cursor-position (0-23)
43      | $2B         | Boot slot * 16 (after boot only)
44      | $2C         | Lo-res line end-point
48      | $30         | Lo-res COLOR * 17
50      | $32         | Text output format [63=INVERSE 255=NORMAL 127=FLASH]
51      | $33         | Prompt-character (NOTE: POKE 51,0:GOTO LINE # will
        |             | sometimes prevent a false NOT DIRECT COMMAND 
        |             | obtained with GOTO # alone.)
74-75   | $4A-$4B     | LOMEM address (INT)
76-77   | $4C-$4D     | HIMEM address (INT)
78-79   | $4E-$4F     | Random-Number Field
103-104 | $67-$68     | Start of Applesoft program- normally set to $801
        |             | (2049 decimal) and location $800 is set to $00. 
        |             | NOTE: To load a program above hires page 1 (at
        |             | $4001), POKE 103,1: POKE 104,64: POKE 16384,0  
        |             | and LOAD the program.
105-106 | $69-$6A     | LOMEM Start of varible space & end of Applesoft prgm
107-108 | $6B-$6C     | Start of array space  (FP)
109-110 | $6D-$6E     | End of array space  (FP)
111-112 | $6F-$70     | Start of string-storage  (FP)
115-116 | $73-$74     | HIMEM- the highest available Applesoft address +1
117-118 | $75-$76     | Line# being executed.  (FP)
119-120 | $77-$78     | Line# where program stopped.  (FP)
121-122 | $79-$7A     | Address of line executing.  (FP)
123-124 | $7B-$7C     | Current DATA line#
125-126 | $7D-$7E     | Next DATA address
127-128 | $7F-$80     | INPUT or DATA address
129-130 | $81-$82     | Var.last used. VAR$=CHR$(PEEK(129))+CHR$(PEEK(130))
131-132 | $83-$84     | Last-Used-Varible Address  (FP)
175-176 | $AF-$B0     | End of Applesoft Program (Normally=LOMEM)
202-203 | $CA-$CB     | Start of Program Address (INT)
204-205 | $CC-CD      | End of Varible Storage (INT)
214     | $D6         | RUN Flag (POKE 214,255 sets Applesoft run-only.)
216     | $D8         | ONERR Flag (POKE 216,0 cancels ONERR; en norm errs)
218-219 | $DA-$DB     | Line# of ONERR Error
222     | $DE         | Error Code  (FP)
224-225 | $E0-$E1     | Horizontal Coordinate of HPLOT
226     | $E2         | Vertical Coordinate of HPLOT
232-233 | $E8-$E9     | Start address of Shape Table
241     | $F1         | 256 - SPEED value (SPEED=255 --> $F1: 01)  (FP)
250-254 | $FA-$FE     | Free Space (normally open to user)

--Jon Relay and Apple II Textfiles ( ).


Useful CALLs

Example: from the BASIC prompt, CALL -151 enters the monitor.

 Hex   Dec
$BEF8 48888  ProDOS- recovers from "NO BUFFERS AVAILABLE" error
$D683 54915  Inits Applesoft stack- scraps false "OUT OF MEMORY" error.
$F328 -3288  Repairs Applesoft stack after an ONERR GOTO handles an error.
$F3D4 -3116  HGR2
$F3DE -3106  HGR
$F3F2 -3086  Clear HI-RES screen to Black
$F3F6 -3082  Clear HI-RES screen to recent HCOLOR
$F5CB -2613  Move HI-RES cursor coords to 224-226
$F832 -1998  CLEAR LO-RES SCREEN 1 and set GRAPHICS mode.
$F836 -1994  CLEAR top 20 lines of LO-RES Graphics
$F847 -1977  CALCULATE LO-RES Graphics base ADDRESS.
$F85F -1953  Change LO-RES COLOR to COLOR + 3
$F940 -1728  PRINT contents of X & Y (REG 9 as 4 HEX digits)
$F94C -1716  PRINT X BLANKS (X REG contains # to PRINT)
$FA86 -1402  IRQ HANDLER
$FAD7 -1321  to display USER REGISTERS
$FB2F -1233  TEXT- screen init
$FB39 -1223  set SCREEN to TEXT mode
$FB40 -1216  GR- set GRAPHICS mode
$FB4B -1205  set NORMAL WINDOW
$FB60 -1184  Prints the 'Apple ][' at the top of your screen.
$FC10 -1008  to MOVE CURSOR LEFT
$FC1A  -998  to MOVE CURSOR UP
$FC42  -958  CLEAR from CURSOR to END of PAGE (ESC -F)
$FC70  -912  SCOLL UP 1 LINE (Destroys ACCUMULATOR & Y-REG)
$FC95  -875  Clear entire Text line.
$FC9C  -868  CLEAR from CURSOR to END of LINE (ESC-E)
$FDOC  -756  GET KEY from KEYBOARD (Destroys A & Y-REG) WAIT for KEY PRESS.
$FD5A  -678  Wait for RETURN
$FD5C  -676  Sound Bell and wait for RETURN
$FD6F  -657  INPUT which accepts commas & colons. Here is an example:
             PRINT "NAME (LAST, FIRST): ";: CALL-657: N$="": FOR X= 512 TO 719
             : IF PEEK (X) < > 141 THEN N$= N$ + CHR$ (PEEK (X) -128): NEXT X

$FDE3  -541  PRINT a HEX digit
$FE2C  -468  PERFORM MEMORY MOVE A1-A2 TO A4. Here is an example:
             10 POKE 60,Source Start address Lo
             20 POKE 61,Source Start address Hi
             30 POKE 62,Source End address Lo
             40 POKE 63,Source End address Hi
             50 POKE 66,Destination address Lo
             60 POKE 67,Destination address Hi
             70 CALL -468

$FE80  -384  set INVERSE mode
$FE84  -380  set NORMAL mode
$FF69  -151  Go to MONITOR
$FF70  -144  SCAN INPUT BUFFER (ADDRESS $200...)

--The Enforcer (on Apple II Textfiles ) and Rubywand 


You can find listings of Apple II soft switches and popular monitor routines in a manual for your computer-- e.g. the Apple II Reference Manual (for II and II+), the IIe Technical Reference Manual, the Apple IIgs Firmware Reference Manual, etc.. 

An excellent guide to many PEEKs & POKEs and monitor routines is the famous "Peeks, Pokes, and Pointers" poster from Beagle Bros (early 1980's). A fairly exhaustive guide to important memory locations in the Apple II is What's Where in the Apple II: An Atlas to the Apple Computer by William Luebbert (1981). 

Other on-line lists of PEEKs & POKEs + Monitor Routines are available at 

Apple II Textfiles 


With very few exceptions, soft switches, monitor routines, and important vectors have remained stable since early Apple II models. So, although an old chart or listing may be missing some which are available on a newer Apple II, the ones shown will almost always work. --Rubywand and Mookie 


005- How can I see and edit what's in a Text file? 

A handy utility for quickly viewing Text files under DOS 3.3 or ProDOS is Copy II Plus. 

On the IIgs under the system Finder (the usual "desktop" display showing drives, folders, etc.) you can, probably, double-click on a text file to start up an application (program) which will display the Text and let you make changes. 

Note: If you get an error message about not being able to find an application, you will want to think about setting up a link between Text type files and some Text editor program such as Teach. Some Text editor New Desk Accessories (like Shadowrite) will automatically establish a linkage. 

Another way to view and edit Text files is to run a Text editor or word processor program and load in the file. On 8-bit Apple II's, some choices include Screenwriter II, AppleWriter, and, depending upon machine, some versions of Appleworks. On the IIgs you have many choices including Teach, Shadowrite NDA, CoolWriter, and Appleworks. --Rubywand 


006- How do I save a BASIC program in ASCII text form? 

The following line added to the front of your Applesoft BASIC program will save it in a Text file named "LISTFILE". It works in DOS 3.3 or ProDOS. 


If you have a line 1 which you'd like to leave alone, you can enter the above at Line 0 and change LIST 2, to LIST 1,. 

POKE 33,33 causes the text display routine to not insert any unneccessary spacing into your BASIC program listing, which cleans up the text file output nicely.

--David Cross 


007- Where and how do I get GS System 6.0.1? 

     You can download System 6.0.1 from several places on the net. You can also buy the set of System 6.0.1 diskettes or buy a hard disk with System 6.0.1 installed. 

For details with links, go to the main Apple II FAQs at ...




008- Where can I get Applesoft shape table info and programs? 

     For information on using shapes in BASIC, go to Ground's Applesoft information folder and see the file hires.routines . For programs, go to the Beagle Bros folder and download SHAPE.MECH1.SHK and SHAPE.MECH2.SHK. 




009- What Operating System environments does the GS support? 

The GS can support several. Some of the more popular OS environments include ... 

DOS 3.3- usually Beagle's Prontodos or some other speeded version of the original DOS 3.3. This is the 5.25" diskette-based disk operating system used for years on earlier Apple II's. It's commands are designed for use from BASIC programs or from the keyboard. Many old Apple II games and other wares are on 5.25" diskettes which boot DOS 3.3. 

ProDOS 8- e.g. ProDOS v2.0.3. This is a disk operating system which supports a variety of devices (e.g. 3.5" drives, hard drives, etc.) and allows sub-directories. Commands are very similar to DOS 3.3 and are designed for use in BASIC programs or from the keyboard. BASIC and 'system' programs can also utilize direct CALLs to well-defined ProDOS Machine Language Interface routines. 

Apple Pascal- This is an early 1980's implementation of UCSD Pascal which can run on 40-column and 80-column Apple II's. 

System- Originally called "ProDOS 16" and later "GS/OS", the collection of 'system stuff' (which includes GS/OS) is today called "System". The System Finder utilizes Toolbox routines to supply a super-res desktop, Windows-like environment. Both ProDOS 8 programs and 'GS Applications' (i.e. wares that need GS/OS to run) can be started from the desktop. Depending upon factors such as installed RAM and presence of a hard disk, System will usually be System 5.0.4 or System 6.0.1. System 5.0.4 is generally appr
opriate for 1.25MB or smaller non-hard disk GS's. Booting a reduced System 6.0.1 often works fine for running Sys 6 software, too. System 6.0.1 is definitely recommended as the default System for larger memory GS's with a hard disk. --Rubywand and David Empson

GNO- GNO is a UNIX-like multitasking environment for the Apple IIgs which runs on top of the native operating system, GS/OS. 

--Rubywand, David Empson, Devin Reade, Jeffrey Iverson


010- How do I write programs for the Apple Graphics Tablet? 

     The Apple Graphics Tablet I know of is rather large and heavy; its pen is attached to it with a (too short) cable; it makes funny sounds that change when the pen is moved in/out of the reach of of the tablet.

     A long time ago I patched a few programs to make use of this tablet. To make it clear in the first place - I don't have these patched versions available anymore :-(. But I found a listing from which I can tell you this:

     To detect the interface card, I looped over all slots to check in its firmware for

$B0 at location $Cx01 and
$20 at location $Cx09

x being the slot number. I never found this 'signature' in any other firmware.

     To check for the pen position one has to poll the tablet (again x being the slot number):

LDA $CFFF ; switch off all extension ROMS

LDA $Cx00 ; switch on the extension ROM of the tablet

LDA #$Cx

STA $07F8 ; initialize some hidden text screen data area for the tablet firmware

JSR $CBB9 ; call well known location ;-) in tablet firmware

     When the pen is in reach of the tablet (up or down) this routine will return immediately. Else it will block - fortunately, the routine checks the keyboard strobe ($C010) too and will also return if a key is pressed, even if the pen remains out of tablet's reach.

     After the routine has returned one can get the information:

$0280 pen state:

 bit 0 = 0 Pen down, bit 0 = 1 Pen up
 bit 1 = Previous pen state
 bit 4 = 0 Pen has been localized, its state and positions are valid.
 bit 4 = 1 Pen out of reach but key pressed and then X=Y=0

$0281 Low byte of X pen position
$0282 High byte of X pen position

$0283 Low byte of Y pen position
$0284 High byte of Y pen position

     X and Y have 13 bits resolution from 0 to 8191. Using my Apple Tablet, I get values from 300 to 6350 and the bounds are not reached.

--Oliver Schmidt, Guillaume Tello, Shaun Olson


011- A while ago someone posted about how to read the joystick on 
     a GS in native mode. They said that it was possible to read 
     both paddles at once and therefore get much more accurate 

Only the high bit of these locations is valid. When the high bit of either location becomes 0 then the corresponding analog input has timed out. 

You will actually get more accurate results by reading them one after the other with the accumulator set to 8 bits wide and the index registers used to hold the counts (16 bits wide). This allows for a much faster loop, giving better resolution. Assuming that this routine is called from full native mode, the following code will do the trick: 

strobe equ $C070 ; analog input timing reset
pdl0 equ $C064   ; analog input 0
pdl1 equ $C065   ; analog input 1

start php        ; save processor status register
phb              ; and data bank register
sep #%100000     ; make accumulator 8 bits wide
lda #0           ; make data bank = 0
ldx #0           ; initialize the counters
lda strobe       ; strobe the timing reset
loop1 inx        ; increment pdl0 count
lda pdl0         ; is high bit = 0?
bmi loop1        ; no, keep checking
lda strobe       ; yes, strobe the timing reset again
loop2 iny        ; increment pdl1 counter
lda pdl1         ; is high bit = 0?
bmi loop2        ; no, keep checking
plb              ; yes, restore data bank
plp              ; and processor status register
rts              ; return to caller (could be RTL)

Notice that the actual counting loops are only 9 cycles long. This gives the best possible resolution. You will need your counters to be 16 bits wide as the results will easily overflow the capacity of an 8 bit counter. 

Using memory locations as counters will only serve to slow the counting loop down. If X and Y contain valid data before entry, you will need to save them off to the stack and pull them back in after interpreting the joystick results. I have used this exact method to read the analog inputs on my Science Toolkit box which connects to the joystick port. 

The results have been extremely accurate (much more than would be needed for a game which reads the joystick). (System Administrator) 


012- How do I write programs which use the mouse? 

     The assembly language interface to the mouse firmware is documented in the reference material that was supplied with the IIe AppleMouse card, the IIc Technical Reference Manual, and the IIgs Firmware Reference Manual.

     For a 'how to' discussion, see csa2 FAQs Resource file R034MOUSEPRG.TXT at ... . 

--David Empson 



013- Where can I find manuals and other resources for the CP/M
     operating system?

     These sites are imho the BEST sites for CP/M related downloads: 

Dr. Tom's large Apple II CP/M collection on Asimov 
See  A2.CPM. ...  stuff at ... 

Also, see other CP/M materials on Asimov: 

The CP/M ver 1.4 & 2.x Programmer's Reference Guide on Paul Schlyter's Apple II Stuff: 

Other good sources: . 

     I've asked Michael Haardt, author of cpmtools, to incorporate some code changes that would allow his package to work on apple II cpm images (both in dos and prodos order).  This package allows one to manipulate cpm disk images - extract, copy, delete, etc, etc from a unix command line. With version 1.6, cpmtools can now handle apple II cpm images.

The very latest cpmtools can be downloaded from 

With cpmtools, I've been able to create Apple II images with the generic software obtained from 

and from the oakdale CP/M archives. These images I've been able to download to an Apple II via ADT without any problems.  I feel that they would be of use to Apple II CP/M users. 

--Bart, Celt, Raoul Golan, Paul Schlyter 


014- How can I view and enter code using the "monitor"? 

Every Apple II has a built in "System Monitor", which lets you play around with memory contents. 

To get into it, start in BASIC and type CALL-151. 

You then get an * prompt to indicate you are in the monitor. To get back to BASIC at a later point, press Control-C then return (on a line by itself). 

The monitor has a lot of commands and the syntax is rather cryptic. Everything is entered and displayed in hexadecimal (base 16). 

The simplest commands are a single letter. For example, the "I" command sets the display to inverse, and "N" sets it to normal. 

The next level up in complexity are commands which expect a single address parameter. The address must be entered first, followed by the command letter. In some cases, the monitor remembers the last address used, so you can continue where you left off by using the command letter by itself. 

An example of this is the "L" command (list) which disassembles 20 instructions. The normal usage is to enter the start address followed by an "L". After you've seen one screenful, type "L" by itself and you get another screenful continuing from the next address. 



The first command will list the first page of code for the Applesoft BASIC interpreter, and the second command will list the second page. 

You can use multiple commands on the same line, as long as you know what you are doing. If you don't mind pausing and resuming the scrolling output (use Ctrl-S to pause, any key to resume), you can do something like: 


to get several pages of disassembly at once. 

Moving up another step are commands that accept a range of addresses. The address range is entered, with the start and end address separated by a period (fullstop), and the command letter (if any) goes on the end. 

The best example of this is a memory dump, which doesn't have a command letter. If you want to display a range of bytes as a hex dump, use something like this: 


The monitor displays eight bytes per line, with the address at the beginning of each line. If you don't start on a multiple of eight, then the first line will have less than eight bytes and subsequent lines will be aligned on eight byte boundaries. 

There are variations on the memory dump that can be used for special cases: 

1. You can press return on a blank line to display the next eight bytes. 
2. If you enter an address and press return, one location is displayed. 
3. You can continue from the end of the previous dump to a specified address by entering a dot followed by the end address. 

You can also display scattered locations by entering them as separate commands. For example: 

E000 E003 E006 

will display the three specified locations, one per line. 
The third layer of command complexity are the commands which expect a destination address and a source address range. The destination address goes first, then a less-than sign, then the source range (with a dot in the middle), and finally the command letter. The main example of this is a memory move ("M"): 


This will move 8192 (2000 hex) bytes from locations 6000 through 7FFF down to 4000. 

If your source and destination ranges overlap, the move will work correctly if you are moving data to a lower memory location, but if moving to a higher location you will get a repeating pattern of the data from the start of the source range. 

There is one major command that breaks the rules above: the "set memory" command. The general syntax for this is the start address followed by a colon, then a space-separated list of bytes to be entered into memory. If you enter more than two digits for the data bytes, only the low order two digits are used. 

If you are entering a lot of data, you can continue the command on subsequent lines by starting the command with a colon (no address). 

The rest of the command line after the colon is regarded as part of the data to be entered, unless the monitor encounters a single letter command first. 

For example, the following single line command will enter a short machine code program and disassemble it. The "N" command (normal) is used as a dummy command to force the data entry to terminate. 

300:20 58 FC A9 C8 20 ED FD A9 E9 20 ED FD 20 8E FD 60 N 300L 

Having got all that out of the way, here are the major monitor commands, each given in example form. 

<return>          Display next line of hex dump
1000              Hex dump one location
1000.101F         Hex dump a range of locations
.102F             Continue hex dump to specified address
1000:1 2 3 50     Set memory
:51 52 53         Continue set memory
300G              Go - call subroutine at specified location
G                 Go again - call same address as last time
I                 Inverse
300L              List - disassemble 20 lines
L                 List again - continue disassembly
1000<2000.207FM   Move - copy range to destination address
N                 Normal
1000<2000.207FV   Verify - compare range to destination address

There are also several commands that use control characters: 

Ctrl-B Cold start BASIC (avoid this) 
Ctrl-C Warm start BASIC 
Ctrl-E Display the saved CPU registers 
Ctrl-K Set input to specified slot (preceded by slot number) 
Ctrl-P Set output to specified slot (preceded by slot number) 
Ctrl-Y User command 

The Ctrl-E command also lets you set the saved CPU registers, which will be used on a subsequent G (go) command. Type Ctrl-E then a colon, followed by the data to place into the A, X and Y registers. 

The Ctrl-K and Ctrl-P commands should be avoided if you are running under DOS 3.3 or ProDOS, because they may cause DOS to be disconnected from the I/O. Use PR#n or IN#n instead. 

Ctrl-Y is an "escape hatch", which allows third-party code to hook into the monitor for this one command. 

On the Apple IIgs, IIc (with UniDisk ROM or later), and enhanced IIe there is also a mini-assembler which can be accessed from the monitor by typing an exclamation mark as a monitor command. While in the mini-assembler you enter lines of the form Address:Instruction, or to enter instructions in sequence, type a space then the instruction. (You must specify the address for the first instruction, or you could be writing anywhere.) Press <return> on a blank line to get back to the monitor. 

e.g. starting in the monitor, type in the following: 

1000:JSR FC58 
LDA #C8 
LDA #E9 

This is the same program I gave above as an example of the set memory command, loaded at a different location. 

--David Empson 


015- What parts of Apple II memory should a user be careful about
     modifying when using the monitor? 

It is important to keep in mind that you can do all sorts of nasty things to the computer if you play around in the monitor and don't know where things are located in memory. 

The safest bet if you want to have a play would be to start the computer with no disk in the drive, then get into the monitor. 

Don't play around with the following memory areas at all (unless you know exactly what you are doing): 

0020-004F Zero page memory area used by the monitor 
0100-01FF Stack 
0200-02FF Input buffer 
03D0-03FF System vectors 
C000-C0FF I/O space. Don't even read memory in this area 
          unless you know what you are doing. 
C100-C7FF I/O firmware (usually ROM on cards in slots, or 
          emulated slots). Some I/O cards may have I/O 
          ports in this area (but not for the IIc). 
C800-CFFF Bank-switched area used by I/O cards. It is safe 
          to read this area in the IIc, but it has to be 
          handled carefully in other machines. 

The following areas must be handled carefully to avoid problems: 

0050-00FF Zero page memory area used by Applesoft BASIC 
0400-07FF Text screen and "screen holes", which contain 
          system data 
D000-FFFF ROM and bank-switched RAM ("language card"). 
          Don't write anything into this area, especially 
          if you are running under ProDOS. 

Other memory areas that you may need to be aware of: 

0800-???? Applesoft BASIC programs normally go here, 
          followed by variables 
2000-3FFF Hires graphics buffer for page 1 
4000-5FFF Hires graphics buffer for page 2 
9600-BFFF Normally used by DOS 3.3 or ProDOS 
????-95FF Normally used for strings in Applesoft BASIC 

The hires graphics buffers are only an issue if you need to use them. Under DOS 3.3 or ProDOS, the upper memory limit (9600) may change depending on the use of the MAXFILES command under DOS or the number of open files under ProDOS. 

This leaves you with the following areas that you can usually play with to your heart's content. There are _some_ exceptions, but I've covered enough for one article. 

0000-001F This isn't entirely free, but is usually OK. 
0300-03CF Often used for small machine code programs. 

The last area varies wildly depending on the size of any BASIC program and its variables. 

--David Empson 


016- Can I do multi-tasking on a IIgs? or What is GNO/ME? 
GNO/ME is a programming shell (a command line environment) for the Apple IIgs.  Designed as a replacement for the ORCA Shell, GNO/ME works in a manner similar to the Unix operating system, providing preemptive multitasking of multiple text programs, as well as many Unix commands and library functions. 

For GNO/ME information and software: 

GNO Consortium-
GNO/ME USENET newsgroup (comp.sys.apple2.gno) and FAQs at 

--Bryan Ogawa 


017- Which Zero Page locations are likely to be in-use? 

     When it comes to writing compact fast-executing code, knowing which Zero Page locations are available is essential information for assembly language programmers. 

     The chart here uses information from Apple's Apple II technical references, Beneath Apple DOS (by Worth and Lechner), and Exploring Apple GS/OS and ProDOS 8 (by Little). It shows which Zero Page locations are used by the Monitor, Applesoft BASIC, Integer BASIC, DOS 3.3, ProDOS, and ProDOS BASIC.SYSTEM. 

                      Apple II Zero Page Usage 

                        Lo Nibble of Address 
Nib  0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F 
     --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 
 0 | A~  A~  A   A   A   A   -   -   -   -   A   A   A   AI  A   A 
 1 | A   A   A   A   A   A   A   A   A   A   A   A   A   A   -   M* 
 2 | M   M   M   M   M3  M   MA3 MA3 M3  M3  M3  M3  MA3 MA3 M3  MA3 
 3 | MA  M   MA  MA3 M   M3  M3B M3B M3B M3B M~  M~  MA3~MA3~MA3~MA3~ 
 4 | M3~ M3~ M3~ M3~ M3~ M3~ M3~ M3~ M3~ M3~ I3~ I3~ I3~ I3~ M~  M 
 5 | MA  MA  MA  MA  MA  MAI AI  AI  AI  AI  AI  AI  AI  AI  AI  AI 
 6 | AI  AI  AI  AI  AI  AI  AI  AI3 AI3 AI3 AI3 AI  AI  AI  AI  AI3 
 7 | AI3 AI  AI  AI3 AI3 AI  AI3 AI  AI  AI  AI  AI  AI  AI  AI  AI 
 8 | AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI 
 9 | AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI 
 A | AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI3 
 B | AI3 AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI 
 C | AI  AI  AI  AI  AI  AI  AI  AI  AI  AI  AI3 AI3 AI3 AI3 I   I 
 D | AI  AI  AI  AI  AI  AI  AI3 I   AI3 AI3 AI  AI  AI  AI  AI3 AI 
 E | A   A   A   A   A   A   A   A   A   A   A   -   -   -   -   - 
 F | A   A   A   A   A   A   A   A   A   A   -   -   -   -   I   AI 

M = Used by Monitor; * used in early Apple IIe ROMs-- now free 
A = Used by Applesoft BASIC 
I = Used by Integer BASIC 
3 = Used by DOS 3.3 
~ = Used by ProDOS ($40-$4E is saved before and restored after use) 
B = Used by ProDOS BASIC.SYSTEM (also uses all Applesoft locations) 
- = Free; not used 

--Bryan Dunphy, Michael J. Mahon, Rubywand
hy, Michael J. Mahon, Rubywand

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Last Update March 27 2014 @ 02:11 PM