Open inexorabletash opened 1 month ago
Here's a practical example, and how I noticed the problem in the first place:
What I see via VGA:
What I see via Composite:
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.
Try this on an Apple IIe with RAMWorks or compatible:
Boot to a BASIC prompt, then enter:
12
(inverse)92
(inverse)What's happening:
Analysis:
Hardware: Enhanced Apple IIe, w/ A2VidGA, RAMWorks compatible from GW