Power20 is an emulator for the Commodore VIC-20. It allows you to run your favorite VIC-20 software on your Apple Macintosh (PowerPC or intel-based) at full speed with smooth graphics and great sound.
2.2 Installation and Registration
There is no special installation procedure necessary to enjoy Power20. Just copy it to a convenient location on your hard disk and run it. It is not necessary to obtain any extra files (such as System ROM images); everything is included in the Power20 application file. Still, you should remember that you need to register your copy of Power20 if you want to play more than 10 minutes at once. Since you've already sent your registration fee as described in the previous section (You havesent it, haven't you?), you should now start Power20. It will automatically display the about dialog (If you've already dismissed it, select "About Power20" from the Apple menu). Now click on the Register button, and enter your name and registration number exactly as stated on your registration email/postcard. Hint: Use Cut & Paste to avoid typos.
2.3 Creating a new emulated VIC-20
To create a new VIC-20 emulator, select File/New (Cmd-N). A dialog will appear where you can now choose the size of the RAM Expansion and the video mode.
The real VIC-20 was shipped with only 5 KByte RAM (plus 1 K 4-Bit Color RAM). 1 KByte was consumed by the Operating System and 0.5 KByte for Video Memory, leaving just 3.5 KByte for applications. This was too little and many people installed RAM extensions on their machines. These were available in 3 KByte, 8 KByte, 16 KByte and 24 KByte. Unfortunately the address of the Video RAM changes when a RAM Extension of 8KByte or more is installed. This does cause problems with certain games, that expect a specific memory extension (because they had exactly that amount of memory in their cartridge). Some games that work with an unexpanded VIC-20 or with a 3 KByte RAM extension will not work with a 8 KByte RAM Extension. More memory is NOT always better. It is always best to know, how much memory a given application requires, and fortunately the games at ftp://ftp.zimmers.net/pub/cbm/vic20/ are sorted by the amount of RAM extension required. If you want to run software, where you lack any clue towards the correct RAM extension requirements I suggest that you use the following order for your trials: Unexpanded, 24 KByte Expansion, 3 KByte Expansion, all others.
You can change the amount of RAM available to a VIC-20 at any time using Devices/System Configuration (Cmd-E). While the new memory configuration goes into effect at once, the VIC-20 operating system will detect the change only if you cause a reset using File/Reset (Cmd-K).
To make things even more complicated there are also two video modes. NTSC as used by North American VIC-20s and PAL as used in Europe. The main difference from the point of VIC-20 emulation is precise video timing and the way the image is centered on the screen. Most games will run fine on both PAL and NTSC. Some will run, but the image is badly off-center and you should use Devices/System Configuration (Cmd-E) to switch the Video-Mode. Few games will not work at all, when started with the wrong video mode. For some games it is possible to determine the correct video mode from the filename or the description in the index.html file, for all others you are limited to trial and error.
2.4 Running a Cartridge Game
1) Unless you already have a suitable emulator window open, create a new VIC-20 as described in section 2.3. For cartridge games, it usually does not hurt to assign too much RAM. Using 24 KByte RAM + 8 KByte Cartridge is usually a good choice. Otherwise try Unexpanded.
2) Select Devices/Connect ROM Module (Shift-Cmd-M). A file selection dialog will come up asking you for the cartridge ROM file.
You can also select a ZIP, GZ or LHA compressed file. Power20 will automatically expand the cartridge before loading.
3) If the game consists of several ROM then repeat Step 2 until all parts of the game cartridge are connected to the VIC-20.
4) Select File/Reset (Cmd-K), to start the game. This will not work if the cartridge was not installed in the memory area ($A000-$BFFF). Some cartridges are loaded in the upper memory expansion area ($4000-$7FFF or $6000-$7FFF). Try SYS 32592 to start those (this may or may not work, depending on the cartridge in question).
5) Enjoy
2.5 Running a Game from the Hard Disk (*.PRG/*.CBM or *.P00) Files
1) Unless you already have a suitable emulator window open, create a new VIC-20 as described in section 2.3.
2) Select Devices/Disk Drive #8/Attach Hard Disk (Cmd-Shift-D). A folder selector dialog will come up asking you for the folder on your Mac hard disk where you keep your *.PRG/*.CBM or *.P00 file.
3) The directory of the selected folder will be listed in a new window.
4) Double-click on the game you want to play. Power20 will execute the commands LOAD"My favorite Game",8 and RUN.
You can also select a ZIP or GZ compressed file. Power20 will automatically expand the game before loading.
5) Enjoy!
The above procedure assumes that you are using the default options. If you have not modified the Device Options (Options/Device Options), the directory window might not open automatically. Also a different command can be selected at this option dialog.
If you want a more VIC-20 like feeling (a mouse and clicking on things is not really VIC-20 like) you can also pursue the following, more traditional approach:
3a) Type: LOAD"$",8 <Enter>
Power20 will load the directory of the disk.
4a) Type: LIST <Enter>
Power20 will show the name and size (in Blocks of 254 Byte) of all files on the tape.
5a) Select your favorite game from the list displayed and type: LOAD"My favorite Game",8 <Enter>
Note: You do not need to type out the entire filename. You can type only the first few characters and use the wild card '*' to indicate that the first file whose name begins with these characters is to be loaded.
You can use LOAD"*",8 <Enter> to load the first file.
6a) Type: RUN <Enter>
7a) Enjoy!
2.6 Using ZIP Archives with VIC-20 programs
If you have lots of VIC-20 programs in *.PRG/*.P00 format each in a separate file, then your hard disk is likely to be cluttered and it is easy to become confused. Often it is convenient to join all these small files into a single ZIP archive, restoring order and saving space on the Mac hard disk.
Power20 can mount ZIP archives just like folders of the Mac hard disk and load games from them. Writing to a ZIP archive is not possible in Power20.
1) Unless you already have a suitable emulator window open, create a new VIC-20 as described in section 2.3.
2) Select Devices/Disk Drive #8/Attach ZIP Archive. A file selector dialog will come up asking you for the *.ZIP archive.
3) The directory of the selected archive will be listed in a new window.
4) Double-click on the game you want to play. Power20 will execute the commands LOAD"My favorite Game",8,1 and RUN.
5) Enjoy!
Similar the the note in section 2.5 this assumes standard options. The traditional way, explained there is also usable for ZIP archives.
If you plan to create ZIP archives yourself, please take care that you do NOT accidently perform linefeed translations (Option LF in ZipIt) or MacBinary encoding (Option MB in ZipIt). Both options make it impossible to use the archive.
Power20 removes all directory structures in ZIP archives. You should therefore place all files at the top level of the archive.
2.7 Running a Game from a Disk Image (*.D64, *.X64) File
1) Unless you already have a suitable emulator window open, create a new VIC-20 as described in section 2.3.
2) Select Devices/Disk Drive #8/Insert Floppy Disk (Cmd-D). A file selector dialog will come up asking you for the *.D64 or *.X64 file. You can now choose a plain *.D64 or *.X64 file, or select a (ZIP, GZ or LHA) compressed file, that contains a *.D64 or *.X64 file. There is no need to manually decompress a ZIP,GZ or LHA file. If the archive contains several suitable files (e.g. multi-disk games or demos), Power20 will ask which one you wish to use.
3) The directory of the selected disk image will be listed in a new window.
4) Double-click on the game you want to play. Power20 will execute the commands LOAD"My favorite Game",8,1 and RUN
5) Enjoy!
The above procedure assumes that you are using the default options. If you have not modified the Device Options (Options/Device Options), the directory window might not open automatically. Also a different command can be selected at this option dialog.
If you want a more VIC-20 like feeling (a mouse and clicking on things is not really VIC-20 like) you can also pursue the following, more traditional approach:
3a) Type: LOAD"$",8 <Enter>
Power20 will load the directory of the disk.
4a) Type: LIST <Enter>
Power20 will show the name and size (in Blocks of 254 Byte) of all files on the tape.
5a) Select your favorite game from the list displayed and type: LOAD"My favorite Game",8 <Enter>
Note: You do not need to type out the entire filename. You can type only the first few characters and use the wild card '*' to indicate that the first file hose name begins with these characters is to be loaded.
You can use LOAD"*",8 <Enter> to load the first file on a disk.
6a) Type: RUN <Enter>
7a) Enjoy!
Usually Power20 uses a very fast, but not 100% accurate method to access the disk. Some (extremely rare) games, that need to fetch additional data from the disk after loading, do not rely on the VIC20-ROM routines to access the disk, but directly access the hardware to boost the floppy performance. These games will fail to load with this fast methods of floppy access. To run these games it is necessary to select Devices/Disk Drive#8/Complete 1541 Floppy Emulation BEFORE loading the game. This drastically improves compatibility, but unfortunately also faithfully emulates the poor performance for the original 1541 disk drive. See chapter 5.7 for more details on this topic.
2.8 Running a Game from a ZipCoded (1!, 2!, ...) Disk Image
ZipCode is an alternative to D64 and X64. A ZipCoded Disk Image consists of 4-5 parts, each covering a certain stripe of the disk. To mount such a disk image, proceed just as if you were mounting a D64 image, and select any ONE (not all 4-5) segment in the file selector dialog. Power20 will automatically load the other parts of the disk image. Once the ZipCoded disk image is mounted, it can be used just like a D64 image.
Power20 supports ZipCoded Disks images that have been compressed using ZIP, GZ or LHA. The 4-5 segments of a ZipCoded Disk image can be contained in a single ZIP/LHA file, or each be separate ZIP/GZ/LHA files. Please note, that a single GZ compressed *.D64 disk image requires less disk space, than a single ZIP file containing the 4-5 segments, which in turn is smaller that 4-5 ZIP files containing a single segment of a ZipCoded disk each. Thus using ZIP/GZ compressed ZipCoded Disk Image is not a smart choice for a file format.
2.9 Running a Game from a Tape Image (*.T64) or Lynx File
1) Unless you already have a suitable emulator window open, create a new VIC-20 as described in section 2.3.
2) Select Devices/Tape Drive/Mount Tape (Cmd-T). A file selector dialog will come up asking you for the *.T64 or Lynx file. You can now choose a plain *.T64 or *.Lynx file, or select a (ZIP, GZ or LHA) compressed file, that contains a *.T64 or *.Lynx file. There is no need to manually decompress a ZIP, GZ or LHA file. If the archive contains several suitable files Power20 will ask which one you wish to use.
3) The directory of the selected tape image will be listed in a new window.
4) Double-click on the game you want to play. Power20 will execute the commands LOAD"My favorite Game",1 and RUN.
5) Enjoy!
Some games require that they be run from a floppy disk. To run these programs mount the T64 or Lynx file on drive #8 using the following approach:
2) Select Devices/Disk Drive #8/Mount Tape/Lynx. A file selector dialog will come up asking you for the *.T64 or Lynx file.
Now the T64/Lynx file is mounted as a floppy disk, and you can proceed starting the games as explained in chapter 2.4.
Similar the the note in section 2.4 this assumes standard options. The traditional way, explained there is also usable for Tape Images and Lynx files. Please note that the tape drive does NOT permit the use of explicit wild cards. The first file where the requested filename matches the beginning of the filename will be loaded.
2.10 Running a Game from a Tape Image (*.TAP)
Power20 can also mount raw tapes on a tape drive. Raw tape images offer very high precision of emulation, but *.TAP files are at least 8 times (usually about 10 times) as large as *.T64 files containing the same game. Futhermore the exact emulation of the tape drive brings along the precise emulation of the tape drives speed, which, using the orignal ROM routines of the VIC-20, is about 50 bytes/second, and which can, with the use of special fastloaders, can be boosted to a breathtaking 200-500 bytes/second. Thus loading a game from a *.TAP file will usually take several minutes. Use Options/Turbo Boost (Cmd-B) to accelerate the VIC-20 while loading.
1) Unless you already have a suitable emulator window open, create a new VIC-20 as described in section 2.3.
2) Select Devices/Tape Drive/Mount Tape (Cmd-T). A file selector dialog will come up asking you for the *.TAP file. You can now choose a plain *.TAP file, or select a (ZIP, GZ or LHA) compressed file, that contains a *.TAP file. There is no need to manually decompress a ZIP, GZ or LHA file.
3) The directory of the selected tape image will be listed in a new window. Usually a TAP file will contain a little loader program stored using the regular VIC-20 ROM routines, and lots of data stored in a special fastloader format. Power20 can only interpret the code stored in original VIC-20 format for display in the directory. All other data areas are shown as 'TurboTape Data'. In addition to that, most TAP files contain lots of empty space without useful data.
4) Double-click on the game you want to play. Power20 will execute the commands LOAD"My favorite Game",1 and RUN. Loading can easily take several minutes! Many programs (not all) will display flickering, colored stripes on the screen to indicate that the VIC-20 is still loading. This is no reason to worry.
5) Enjoy!
The characters '?' and '*' that can be used as wildcards for the disk drives have NO special meaning for the tape drive. They are just plain symbols like any other letter. Still there is no need to type the entire filename. The tape drive will load the first file, whose name starts with the the given filename and than continues any way it wants. To load the first file on a tape, use the command LOAD"",1 (or, if device 1 (or 1-8-9) is the default device, just use LOAD without any parameters).
Many tape programs cause trouble, when loaded to an absolute adress. Thus you should always use LOAD"",1 and not LOAD"",1,1
Note: Unfortunately, there is no standard RAM image format among VIC-20 emulators (although there is some discussion on the creation of such a format). Thus it is likely that RAM Images created with Commodore VIC-20 emulators other than Power20 will not work properly with Power20. A warning message will be displayed when Power20 discovers that the RAM image was created by a different emulator.
Note also that loading a RAM image only restores the RAM, the I/O Area and the CPU-registers. It does NOT restore any options such as selected joysticks, or screen refresh rates.
2.12 General Hints on Game Controls
Once a game is successfully loaded and started it will usually display some kind of intro- screen. To start the actual game you usually have to press a key on the keyboard or press the joystick fire button. Which key must be pressed depends on the game you want to play. Usually it is one of the following: Space, Return, F1, F7 (or F3, F5).
The original VIC-20 featured a joystick port. By Default Power20 uses the keys 4568-0 of the numeric keypad (or, if and only if your keyboard does not have a numeric keypad, use the cursor keys and the control key) to simulate the joystick. Power20 also supports USB-joysticks connected to the Macintosh. See chapter 5.5 (Joysticks) for more details.
2.13 Troubleshooting
Here are some common problems explained in Question and Answer form:
Q: Could you please send me a copy of my favorite game XYZ?
A: No! I do not distribute games to play with Power20! Check out section 3 of this document for FTP sites that have all the games that your heart might desire.
Q: My favorite game fails to load or the message 'COMMAND (XYZ) NOT EMULATED' appears in the bottom line of the disk directory window. What can I does that mean and what can I about it?
A: Power20 usually uses a disk emulation that is tuned for speed rather that optimal compatibility. If it encounters a command that it can not handle it displays the 'COMMAND (XYZ) NOT EMULATED' message (It is possible that this message is not visible if the game loader read the error message and thereby resets it to OK). You can select a better, but slower disk emulation by selecting Devices/Disk Drive #8/Complete Floppy 1541 Emulation. The disk emulation mode must be chosen BEFORE you start loading the game. Drawback: Complete Floppy Emulation is slow. It will take several minutes to load a large game.
Q: What do those number in the top/right corner mean?
A: The first number (x.xxMHz) indicates the speed of the virtual M6502 CPU of the emulated Commodore VIC-20. Its value should be 1.10 for PAL-mode (preferred) or 1.02 for NTSC-mode. The second number (yy%) indicates how busy the Macintosh CPU is. When this number approaches (or even exceeds) 100% you will get bumpy motion and wailing sound. In the second line you can see the frame rate of Power20. The first number gives the number of frame redraws/second. The number in parentheses shows how often the screen would be redrawn on a real VIC-20 (50 for PAL-mode, 60 for NTSC)
Q: Why is there a countdown at the bottom of the emulator window, and why does the game automatically stop after when the countdown expires?
A: Power20 is shareware, and fully functional even without registration. However to remind you that registration is required if Power20 is used for an extended period, each emulator session is limited to 10 minutes for unregistered copies.
Q: When I press Cmd-K to reset the emulated VIC-20 it does not reset, but restarts the current game or just dies.
A: You have been playing a reset-protected game. To force a complete reset press Option-Cmd-K. This will circumvent the reset protection.
A: No, Power20 contains lots of PowerPC assembler code, that was once necessary to achieve 100% emulation speed and that now needs to be manually rewritten for Intel-Macs. Never the less Power20 will work fine (with full functionality and speed) on Intel-Macs thanks to Apples Rosetta emulation layer.
Q: I would like to have feature XYZ added to Power20.
A: Send me an Email:
Q: I have a different question!
A: Have you read the manual completely and not found an answer?
Q: I have read the manual from top to bottom and I still have a question!
A: Send it to me (via Email:
) and I will attempt to answer it. Please describe your problem as detailed as possible. Here are some hints as to what information you should include with your question:
What version of Power20 do you use? Have you checked the Power20 homepage to see if a newer version is available that fixes your problem?
What type of Mac do you use? What is your MacOS Version? Are there any unusual hardware or software extensions?
Have you tried booting your Mac without System Extensions? Did it help? Have you been able to determine which Extension is making trouble with Power20? Even if you managed to solve your problem by eliminating that Extension, please tell me that there is a problem that I should fix.
What precisely did you do to cause the problem (Step-by-Step)? Can you reproduce the problem? (Always? Sometimes? Only at an odd chance? Never?) Can you reproduce it at your friends machine?
If Power20 crashes on you please state how severe the crash was. (The VIC-20 game does not respond any more, but the emulator window kept on working (look at the CPU Load indicator!) - One Power20 window crashed, but the rest of Power20 still works - Power20 crashes but you can still work with other Macintosh applications - The Mac comes to a complete stop and a reset is necessary.)
If the problem is related to a specific game? - Where did you obtain that game? Have you tried a different source? I am not familiar with all games. If a game has problem with Power20 let me know; If you have a problem with a game (Where is item ABC in adventure XYZ? What is the best strategy to get rid of the bad guys in the shoot-'em-up XYZ?) please do NOT write to me - I lack the time to solve such puzzles.
Note: I will do not distribute VIC-20 games to play with Power20! Check out the FTP-servers listed in section 3.
2.14 What is new in Power20 4.9.5?
Version 4.9.5: (Feb. 2008)
The fonts in the directory and debugger window are now scalable, to accomodate high-res screens, where 9-point Monaco is simply to hard to read.
Sound Output is broken on some Macs. This used to cause extremly fast emulation in Power20. While the root cause of this bug is still not understood, Power20 now detects the problem and safely falls back to mute emulation.
Power20 sometime had trouble mounting disks via Drag&Drop. This bug has been fixed.
Power20 no longer crashes when saving/loading RAM Images even if disk/tape images are attached.
Power20 no longer crashes when drawing screens in black/white mode.
Added Support for Gamepads
Minor Bugfix for Joystick Support in MacOS 10.4.9
Lots of links in the documentation have been updated/fixed.
For more information on the History of Power20 please read the chapter 7: Version History.
2.15 Future of Power20
Development of Power20 still continues. Features planned for the next releases include:
Save Options with RAM Images
General Bug-fixes (esp. 1541 via HardDisk)
Documentation:
System Variables (low 1KB)
System ROM Routines
Please feel free to tell me about any additional features that you consider important. (Email:
)
