Couple of Mini vMac Updates: Sept. 27, Oct. 4

About Mini vMac and all other 68k emulators, including SoftMac, Executor, and MESS.

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Couple of Mini vMac Updates: Sept. 27, Oct. 4

Post by ClockWise »

A couple of updates over on the Mini vMac page:

October 4, 2020 -

* The latest Development source snapshot fixes a bug where, if the ROM image file that Mini vMac finds is not the desired ROM, but a different valid Macintosh ROM that has been renamed, and the undesired ROM is larger than the desired ROM, Mini vMac would display a “ROM checksum failed” message instead of the “Unsupported ROM” message. This is because Mini vMac loads and computes the checksum of the expected number of bytes, rather than the actual ROM image size. (It is intended behavior that Mini vMac will work if the ROM image file has some extra junk at the end.) Mini vMac now checks that the checksum field at the start of the ROM is recognized, before verifying the actual checksum. Thanks to a bug report for pointing out this issue.

September 27, 2020

* The latest Development source snapshot fixes the bug that the program Winter Games by Epyx would not work in Mini vMac. Thanks to Jesus A. Alvarez (“zydeco”, author of the iOS port) for figuring out why, and providing a patch to Mini vMac to fix it. The game directly modifies the VBL queue data structure of the Macintosh operating system to add a VBL task, instead of calling the operating system routine VInstall, but doesn’t account for the possibility of the queue being empty. The fix is to have the Mini vMac replacement disk driver add a VBL task at boot, as the original disk driver does, so that the VBL queue is not empty.

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