Release Notes for Jcon

Version 2.1 of Jcon includes minor feature additions, documentation edits, and bug fixes. Changes include the following:

• A directory can be read by opening it as a file.
• JPEG images can be written under Java 2 implementations.
• Java class files can be bundled with a Jcon program for easier dynamic loading.
• The run-time system can be bundled with a Jcon program to make it completely self-contained.
• Large integers now work with to-by, seq(), limitation (e1 \ e2), and exponentiation (e1 ^ e2)
• A zero increment value is diagnosed by seq()
• &host no longer spawns a shell invocation of uname (but see Problems, below)
• The run-time package name has been changed from rts to jcon. All programs must be recompiled.

Tested Platforms

Jcon has been successfully tested on:

Sun Sparc / Solaris 2.6 (SunOS 5.6) / Sun Java 1.3beta0
SGI Indigo2 / Irix 6.5 / SGI Java 3.1.1 (JDK 1.1.6N)
IBM RS6000 / AIX 4.3 / IBM Java 1.1.6-19990401
DEC Alpha / Digital Unix 4.0D / Digital Java 1.1.6-2
Intel / Linux 2.2.5 (Red Hat 6.0) / IBM JDK 1.1.6-990814

We would be interested to learn of either successes or failures on other platforms.

Known problems (nongraphical)

• Some JIT compilers fail to execute Jcon programs correctly. Disabling the JIT compiler produces correct execution.
• The -S option of jcont does not work for programs that link other files.
• &clock and &dateline may be off by one hour (Java bug #4059431).
• On Solaris systems, &host may return "localhost" (Java bug #4073539).
• Extremely large procedures (thousands of lines long) can generate code that is too large for Java to handle.

Known graphics problems

Some problems are universal:

• When an obscured part of a window is exposed, it may not be repaired (redrawn) until the program pauses to await an event.
• WOpen("image=file.gif") does not load an image if presented with a multi-part (animated) GIF image.

Other problems are seen only on some platforms and are attributed to Java bugs:

• Fonts can be poor when one vendor's Java system displays on another vendor's X server.
• Different fonts may be written to the window and to and its backup image, leading to bizarre effects from CopyArea() and window repair.
• On one older system, nothing appears in a window until it is dragged to a different location.
• The initial window size may not be as specified:
  • It is one pixel too wide, or
  • It is always the default size, or
  • Its height is correct but its width is the default.
• Intermittently, drawop=reverse draws the wrong color.
• GIF images have a yellowish tint.
• The CopyArea() section of the gpxtest program shows a minor glitch.