2013-06-11 07:08:15 +00:00
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Known issues with the emulator:
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Emulation Fidelity:
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- Disk emulation. The emulator is not very realistic. It handles almost
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all non-copyprotected disk access okay, but copyprotected or diagnostic
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programs may be confused by our drive, which magically spins at precisely
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the optimal speed. (see Specific Programs, below).
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- Medium Resolution graphics. This is a rarely used //e mode that is to
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Low-Res what 80 Column text is to 40 column text. We don't support it as
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yet, although it should be relatively simple.
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- We don't emulate the //e's vertical blanking interval detection feature.
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2014-01-23 04:42:34 +00:00
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This is on the TODO list.
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2013-06-11 07:08:15 +00:00
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Graphics:
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2014-01-23 04:42:34 +00:00
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- Composite graphics artifacts are not emulated. This is on the TODO list.
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2013-06-11 07:08:15 +00:00
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- B/W color setting does not apply to lores or double hires. This
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generally is not an issue in practice though, as it's really only needed
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to avoid color fringing in b/w hires images.
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- Double Hires mode is always 140x192 color. Some applications use it as
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a 560x192 b/w display however. Note that most applications indicate
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which mode they want using the high bit of the dhires data bytes, so it
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wouldn't need to be a preferences setting.
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- If an 80-column mode is selected in the low-res emulator, nothing will
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be written to the display -- the image from the last video mode will
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remain on the screen. If a menu is brought up it will `stick'. This may
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make people think the emulator crashed, although it will recover if the
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application returns to 40-column mode.
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Keyboard:
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- Presently, the Backspace key is interpreted as Left-Arrow (Code 0x88).
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It could be argued that it should be interpreted as Delete (Code 0xff)
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instead. Real Apples had no seperate Backspace key, but the //e's Delete
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key was in an analogous position to the PC's Backspace). The PC
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keyboard's Delete is assigned to 0xff (in //e mode).
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Specific Programs:
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- Some programs (Computist's Nibbler, Sword of Kadash Master copy for
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example) lock up. It appears (in debugger) that they are reading the disk
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with the motor off. Perhaps they pulsed the real Apple's drive motor to make
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it turn slower?
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- ProDOS will refuse to format disks, claiming that the disk is too slow.
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- ``Alternate Reality: The City'' seems to get jammed, rapidly changing
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the video mode. I'm not sure if this is a real failure, or just a special
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effect that takes longer than I'm willing to wait to finish (mode switches
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would be much faster on a real Apple.) I can get into the program
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with some nontrivial debugger manipulation to `short out' the offending loops.
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