The appearance of the cursor is controlled on a BBC micro via VDU 23, the catch-all graphics command which does everything from redefining the font to directly programming the 6845 chip. With VDU 23,1 the cursor can be be made to disappear, flash as normal, or appear steady. VDU 23,1,2| does the trick under BASIC 4, with earlier versions - or the assembler equivalent - we have to use VDU 23,1,2,0,0,0,0,0,0,0. The same effect can also be achieved by direct keyboard input holding down CTRL and pressing W, A, B then the @ key 7 times.

All very nice, but it only lasts until the next change of screen mode, so in order to have a steady cursor when doing things like a SHIFT-BREAK we have to be a bit clever and intercept the BREAK vector.

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