Version 0.03 of MacArc differs in only one significant way from v0.02 -it has NO expiration date! It turned out that having an expiration date wasn't a very good idea, and I apologize to those of you who were inconvenienced or confused by it.
This version does have some internal improvements. Some of the low level i/o has been re-written in assembly language for improved speed, and a few minor bugs have been fixed. I haven't had any time to add new features, though. I still plan to implement the features in the Options menu as soon as I can find the time. You can expect the ability to create new archive files by late Summer.
What is Arc?
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MacArc is file compression and archiving utility based on an IBM-PC program called Arc (I'll call it PC-ARC here to avoid confusion). This is a beta-test version of MacArc. It will only UN-archive files created on an IBM-PC by PC-ARC. (See what I mean by confusion?) Future versions of MacArc will also be able to create archive files that can be read by both MacArc and PC-ARC.
Arc-type programs are most commonly used for telecommunications. They simplify the process of transferring multiple files via modem. Archive files are also about 10-60% smaller than their uncompressed counterparts, so they save download time, too. Files that are in Arc format usually have '.ARC' appended to their filenames.
Using Arc
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To unarchive a .ARC file select 'Open' from the file menu. You'll see the usual list of files on the disk. Click on the file you wish to un-Arc, and press the Open button.
When the file opens, MacArc will display a list of all the files stored in the archive. Select the ones you wish to extract by clicking on them. Shift-click to select multiple files. Press the Extract button when you're ready to extract those files from the archive. The files will be extracted one by one. If the file was stored in MacBinary format, MacArc will automatically convert it during the extraction process. Non-MacBinary files will be extracted and saved as-is.
WARNING: In this very preliminary version, MacArc saves extracted files into the same folder as the archive file. If there is a file in the folder with the same name as the file being extracted, THE ORIGINAL FILE WILL BE OVERWRITTEN. Future versions of MacArc will handle this better. Until then, it's probably a good idea to create a new folder and put the archive file into it before un-Arcing.
IMPORTANT NOTE: When you download an ARC file from a BBS, make sure your terminal program does NOT modify the file in any way.
Most Macintosh programs can tell that an Arc file is not a Macintosh file. Some programs make the false assumption that, since it's not a MacBinary formatted Macintosh file, it must be a plain text file. Really helpful programs may then decide to strip out the linefeeds during the download to make the 'text' file compatible with the Mac. Tell your terminal program NO, NO, NO. Tell it you LIKE the linefeeds in your MacArc files, and to kindly refrain from stripping them.
For example, if you are using Red Ryder make sure the "Strip Linefeeds" option is turned off. Early versions of Turbo Download from Mainstay strip the first byte from the text, also making the Archive file unreadable. Microphone silently modifies files unless the "Macbinary Enabled" switch is turned off. Microphone modified files are particularly insidious, since they look like normal Arc files to MacArc, and the first one or two files in the archive may even be accessible. These files can CRASH MacArc, however, so make sure you don't use them. Other terminal programs may also modify the Arc file on download. FreeTerm, MockTerminal, and Termworks seem to work ok, though.
If you try to unarchive an Arc file and MacArc tells you it's NOT an archive file, it may be because the file has been damaged or modified during the download. Try downloading it again, making sure to turn off any filtering in your terminal program.
The Apple Menu
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The About MacArc... entry will display this help screen. (You figured this out all by yourself? I knew you could.)
All the desk accessories are available under the apple, as well. Desk accessories are fully supported, but since MacArc works entirely in memory, you may need to close all open da's before unarchiving the REALLY big files. MacArc will warn you if it runs out of memory.
The File Menu
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Eventually the New command will mean "create a new archive file." This command will let you archive files of your very own. Until then, you'll just have to look and dream.
The Open command opens archive files so that you can extract their constituent files. The Open dialog box currently shows all the files. Eventually files will be filtered to show only .ARC files, depending on how...
Show All Files is set. When this item is checked, all files are displayed for opening. Naturally it won't do you any good to open anything but Arc files. When the item is unchecked, only files with the extension .ARC will show in the Open File dialog box.
Quit means head for the hills or the Finder (whichever comes first).
The Edit Menu
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The standard edit commands are implemented for the use of desk accessories. MacArc doesn't use them.
The Options Menu
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This menu doesn't do anything, yet. Eventually it will let you control some of the functions of MacArc. It's current, immutable, state shows how MacArc works now, i.e. MacBinary files are automatically converted, gremlins are not zapped, and files with conflicting names are overwritten with nary a squeak.
Error Messages
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The most common error message you'll see will be "This is not an archive file." If you're pretty sure the file you're trying to open IS an Arc file (you're not trying to unArc Excel, say), the problem might be that the file has been damaged somehow. This often happens during downloads. See the IMPORTANT NOTE in the Using MacArc section above.
Another possible error is the Out of Memory condition. This version of MacArc requires enough memory to hold the squeezed and unsqueezed version of the file it's extracting in RAM at the same time. If you're extracting a really big file on a really small machine you might have trouble. The only way to free memory is to close all da's. Closing MacArc's windows does not help. You might also try removing any memory resident software like debuggers and screen blankers.
If you try to extract files that have been archived using a method MacArc doesn't know about, it will tell you it can't unarchive the file. The other files in the archive might still be extractable, however, since Arc uses a variety of different methods, even within a single archive.
When PC-ARC adds a file to an archive it stores a CRC into the archive with it. That's a special 16-bit polynomial number that is unique to the archived file. After extraction, MacArc recalculates the CRC value and compares it with the original - if these CRC values don't match, the file has been damaged in transit. MacArc will tell you about this error, and you should then treat the extracted file with caution.
MacArc allows you to open up to eight archive files simultaneously. If you try to open more than eight windows, MacArc will complain in a loud shrill voice.
Using Help
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This is the complete manual for MacArc as well as a help file. You can use it in one of two ways. If you're reading this for the first time you'll probably want to scroll through the whole thing. Use the scroll bar to move through the text, just as if you were using MacWrite.
If you need help with a specific topic, you can use the Find button to search for it. Enter the text you'd like to search for in the Topic box, then press the Find button. To search for the next occurrence, press Find again. If text you're searching for is not in the help file, MacArc will beep when you press the Find button.
The latest version of this software is always available from MacQueue BBS, 415/661-7374 or 415/753-3002.
MacArc may be distributed freely for any non-commercial purpose. This is pre-release software. It is distributed "as is" and without warranties as to performance. IT HAS NOT BEEN THOROUGHLY TESTED. Please use it with caution, and never use it with any disk that cannot be replaced. The user assumes the entire risk of using the program.
