rallepalaveev / analog

VGA card for the Apple II computer line
MIT License
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Apple IIe - RAMWorks compatibility issue #6

Open inexorabletash opened 3 weeks ago

inexorabletash commented 3 weeks ago

Try this on an Apple IIe with RAMWorks or compatible:

Boot to a BASIC prompt, then enter:

CALL -151
100: 20 00 C3 8D 00 C0 A9 32
108: 8D 00 04 A9 31 8D 05 C0
110: 8D 00 04 A9 01 8D 73 C0
118: A9 39 8D 00 04 4C 1D 01
100G

What's happening:

Analysis:

Hardware: Enhanced Apple IIe, w/ A2VidGA, RAMWorks compatible from GW

inexorabletash commented 3 weeks ago

Here's a practical example, and how I noticed the problem in the first place:

  1. Boot a ProDOS disk with an appropriate RAMWorks disk driver on it, e.g. John Brook's RAMAUX.SYSTEM which creates /RAMA
  2. Without restarting ProDOS, launch Apple II DeskTop (from https://github.com/a2stuff/a2d/releases)
  3. If A2D doesn't start copying itself to RAMDisk, go to Apple > Control Panels > Options and enable the option, then File > Quit and restart

What I see via VGA:

IMG_4357

What I see via Composite:

IMG_4358

Note that in the VGA screenshot, in the even columns at the middle of the screen you can see the inverse ...@@@@@? - this is the ProDOS volume bitmap slowly being populated as the file copy proceeds. The bitmap is apparently in Bank 1 between $400 and $7FF, with inverse @ being $00 or %00000000 which represents 8 in-use blocks, and inverse ? is $3F or %00111111 which is 2 used blocks and 6 free blocks.