I finally have a better understanding what the different graphic accelerator opcodes are doing and it turns out that even though it can only do two things: filling and copying memory it allows for some interesting feedback effects when using the "wrong" values.
Peeking into various areas of the RAM - this looks like where it stores its on-screen menu.
The machine has an LCD screen that shows the time and the selected TV channel. It shares the frame buffer in an invisible area and that part gets updated separately via interrupts. But when blitting rects with wrong strides the hidden parts can make it into the main view.
One interesting aspect of the chip is that the accelerator can read and write anywhere in the RAM - but that can be dangerous when it paints over some code area instead of the frame buffer, in which case the machine shuts down and reboots.
One interesting aspect of the chip is that the accelerator can read and write anywhere in the RAM - but that can be dangerous when it paints over some code area instead of the frame buffer, in which case the machine shuts down and reboots.
I finally have a better understanding what the different graphic accelerator opcodes are doing and it turns out that even though it can only do two things: filling and copying memory it allows for some interesting feedback effects when using the "wrong" values.
And some more
The machine has an LCD screen that shows the time and the selected TV channel. It shares the frame buffer in an invisible area and that part gets updated separately via interrupts. But when blitting rects with wrong strides the hidden parts can make it into the main view.