Sounds like an LCD timing bug on the 84+, thanks for reporting it. Do other graphics commands (try the CLOCK and CUBE demos) work? The pixel-plotting routine writes directly to the LCD (pointless to send 768 bytes to the LCD when only one has been updated) so there could well be a bug in that code.
bwang wrote:Also, cls doesn't seem to clear the bottom few rows of the screen.
CLS clears the text viewport. In
MODEs 0 (the default) and 3 text characters are six pixels high, making the text viewport 96x60 pixels. The bottom four rows are outside the text viewport so cannot be cleared with
CLS.
CLG will clear the graphics viewport, which by default fills the screen. You can change the size of the text and graphics viewports (see the
VDU Emulator documentation) which is why I can't just clear the entire screen with
CLS.
I noticed that the SIERPINS demo doesn't clear the screen properly, I'll look into it.
There is an annoying bug: the files I write sometimes disappear... They are still in memory, but BBC is unable to find them.
And I can't do: SAVE "TESTBBC" if the program don't already exist, whereas the first I did it, it worked.
That's rather more important. Are you doing this on a real calculator or on an emulator? I noticed this happened on Wabbitemu (84+), but never on PTI (83+) or on a real 83+.