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| author | B. Watson <urchlay@slackware.uk> | 2025-11-26 17:53:35 -0500 |
|---|---|---|
| committer | B. Watson <urchlay@slackware.uk> | 2025-11-26 17:53:35 -0500 |
| commit | e9d1cc997a2e6f8a54974c832182aaa9a5f15939 (patch) | |
| tree | 49570c6b5262d86c973b0343a59d3d9faebb241b /src/alf.rst | |
| parent | db64ce4dbbd6c1cf273ce1e557158301ff4a9228 (diff) | |
| download | unalf-e9d1cc997a2e6f8a54974c832182aaa9a5f15939.tar.gz | |
Update notes in alf man page.
Diffstat (limited to 'src/alf.rst')
| -rw-r--r-- | src/alf.rst | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/src/alf.rst b/src/alf.rst index bb55282..8108d7d 100644 --- a/src/alf.rst +++ b/src/alf.rst @@ -67,6 +67,9 @@ EXIT STATUS NOTES ===== +Compatibility +------------- + This **alf** is *intended* to be 100% compatible with the original Atari **LZ.COM** aka **ALF.COM**, with the following differences: @@ -77,10 +80,16 @@ Atari **LZ.COM** aka **ALF.COM**, with the following differences: overwrites (making a backup) by default, and can append with the **-a** option. +- Turning the screen off for speed makes no sense on modern operating + systems, so there's no option for that. + Note that **alf** is a complete reverse-engineered rewrite in C, *not* a port of the original 6502 code as **unalf** is. It's still being tested, and may still contain bugs. +File Size Limits +---------------- + **alf** (and **LZ.COM**) have a 16MB file size limit. **uanlf** actually can't handle files above about 15MB, if you compress one with **alf**. Real Atari 8-bit files are never this large anyway, so it's @@ -88,15 +97,24 @@ a pathological case. A real Atari would take hours or even days to compress/decompress such files, and you'd have to have a hard disk and a DOS capable of handling multi-megabyte files... +It's also impossible to compress empty (0-byte) files. **alf** will +skip them, if any are found. + +Performance +----------- + Performance is *horrible*. This shouldn't be a real problem on modern multi-GHz CPU, especially since most Atari 8-bit files are small (usually under 64KB). Interestingly, it's not O(n^2), it scales linearly, O(1): Compressing a 1.3MB text file takes 0.7 seconds on the author's (rather modest) Intel i7 workstation, and a file 10x as large takes approximately 10x as long (7 seconds). A 50KB file is almost -instantaneous, 0.5 seconds, which is more typical of the files you'd +instantaneous, 0.05 seconds, which is more typical of the files you'd actually use this with. +Timestamps +---------- + The date/time stamps stored in the archive are the **mtime**\s of the files (which is the same time **ls**\(1) shows, by default), and your local timezone is assumed. Only a 2-digit year is displayed by |