Mini vMac 3.1.2 Beta / 3.1.1

Mini vMac 3.1.2 Beta / 3.1.1 is a utility emulating a Macintosh Plus, which is one of the earliest of Macintosh computers, sold between 1986 and 1990. It can run old Macintosh software that otherwise couldn’t be used on recent computers, and so helps to preserve history, from the era when the modern user interface for computers was being defined.

Major Features:

1. Mini vMac is a spin off of the program vMac. It was originally intended to be of limited interest, a simpler version to serve as a programmers introduction to vMac. But vMac hasn’t been updated in some years, and doesn’t have a number of fixes included in Mini vMac, so Mini vMac may now be more generally useful.
2. To meet the goal of preserving early Macintosh software forever, Mini vMac is intended to be as simple and maintainable as possible, while still being usable enough that the software running within it is as usable as ever. Also as part of this goal, Mini vMac is intended to be easily portable to new operating systems. So far it works on Macintosh OS, Microsoft Windows, and the X Window System.
3. Mini vMac requires a ROM image file to run, and so can be legally used only by those who own a Macintosh Plus. This leads to the question, if you need to own the real computer to use it, what is the use of the emulator? First, a real Macintosh Plus won’t last forever. It is common for the power supply to fail. It is still legal to use the emulation after the real computer breaks. And second, the emulation is more convenient than the real thing. It is much faster (on modern computers) and you can use a better screen, keyboard, and mouse. And it is easier to transfer files between the modern computer and the emulator.
4. Some of the very earliest systems versions and applications won’t work on a Macintosh Plus, so Mini vMac can be recompiled to emulate the original Macintosh 128K. Mini vMac can also be recompiled to emulate the Macintosh 512K, 512Ke, and SE.
5. If you would like to run more modern applications that won’t work on a Macintosh Plus (which has an MC68000 processor, 4M of RAM maximum, and a 512 by 342 black and white screen), then you should look for a different emulator. Or buy a Mac.

• New features:
• • If Mini vMac, on Mac OS X or Windows, doesn't find the ROM file in the folder containing the application, it will now also look in a specific central location. In OS X it checks in "/Users/[your_UserName]/Library/Preferences/Gryphel/mnvm_rom/". In Windows XP, "C:Documents and Settings[your_UserName]Application DataGryphelmnvm_rom". Windows 98, "C:WINDOWSApplication DataGryphelmnvm_rom". And in Vista, C:Users[your_UserName]AppDataRoamingGryphelmnvm_rom". Usually "mnvm_rom" would be an alias (on OS X, on Windows this is called a short cut) to where ever you keep your ROM collection. This avoids having to create an alias to the ROM image for each emulated Mac you use.
• Changed behavior:
• • The alternate CPU emulation of Mini vMac 3.0.4 is now the main and only emulation. (The “-alt-cpu” build option is gone.) This makes Mini vMac slightly faster, and allows more accurate detection of illegal instructions without speed penalty. It also reduces the amount of code to be optimized in assembly language (Currently only done for PowerPC). The PowerPC assembly code version has been revised to match the new emulation, and is now used for the PowerPC Linux version.
  • More accurate mouse and keyboard event handling, by using an event queue to communicate between the platform dependent code and the platform independent code. Previously, the the platform dependent code would tell the platform independent code every emulated sixtieth of a second the current mouse position and up/down state of the mouse button and keys. If the host computer was very busy, or just slow, then a down and up pair could end up being processed in the same emulated sixtieth, and they would cancel each other out and be lost entirely. Also a mouse button state change might not be processed until well after it happened, and the mouse position might be different by then. (Though if Mini vMac is not getting time every sixtieth of a second, so that these problems can be observed, then sound emulation isn't likely to work either, emitting horrible noises. But it is possible to compile Mini vMac without sound. And also if the host computer is a device without a keyboard, such as using handwriting recognition, then there might not be separate key down and key up.)
  • The Macintosh and Windows versions now match the X version in not initially filling the sound buffer with silence, but instead waiting to accumulate real sound samples before starting to play sound. This may reduce the tendency to stutter as the program starts, mostly by giving the emulation more time to get settled into a regular rhythm before attempting sound. It is also changed the X version to match the Macintosh and Windows version in only skipping a single sound block on underrun, rather than stop playing sound until the buffer is refilled.
  • Includes code sent by Jesús A. Álvarez ("zydeco") from his iPhone/iPod Touch port that improves support for the Disk Copy 4.2 disk image format, using information found in the Lisa Emulator Project by Ray A. Arachelian. Mini vMac will now get the correct size of the data in a Disk Copy 4.2 disk image, and will identify such an image even if it is not in HFS or MFS format.
  • When Mini vMac is in full screen mode, it tries to send all key events to the emulated computer, instead of any normal meanings they would have in the host operating system. But I've decided that it went too far with this. So now in OS X, in full screen mode, it will no longer disable force quit (command-option-escape). This was just too dangerous, especially during development of Mini vMac. You can still send command-option-escape to the emulated computer, using the F1 and F2 keys, which are mapped to 'option' and 'command'.
  • The X version now uses mouse motion events when possible instead of XQueryPointer, which is alleged to be inefficient. (Especially if the program is using the display on another computer, so that XQueryPointer requires a round trip over the network)
  • Thanks to a tip from William Nolan, Mini vMac now has, when accessing the emulated computer's memory, a special case for little endian processors that allow unaligned access (such Intel), similar to the existing special case for big endian (such as PowerPC). This makes it a bit faster.
  • Have number of small changes to the replacement disk driver that I think make it act closer to original Apple versions. (But which don't make any known observable difference.)