Flashing colours

PROG =0 A PROG =1 A 432A B=■i The proposed circuit has been de- signed for insertion between the digital RGB(I) outputs of the Elektor high-resolution colour system and a RGB(I) monitor; see Elektor Elec- tronics, issues from September 1985 onward. The colour inversion and flashing effects are entirely under software control (BASIC); they are easily brought about by writing ap- propriate data to a specific memory location, as will be explained further on in this article. Since the proposed design of the flash/invert extension is fairly universal, other graphics col- our systems may also incorporate it, 1 VB 0067 000 3 FT§2 D10 18 RI provided the necessary control signals are available. Colour inversion One of the fundamental operations in Boolean algebra is referred to as the exclusive-OR (EXOR) bit manipu- lation method, which is a means for controlling the digital polarity (in- verted/non-inverted) of an operand A when this is applied to either one input of an EXOR type logic...