Daphne

Daphne is the original version of Denise. It was designed by Dave Dean and Jay Miner. Its resolutions were originally 640 x 400 for an RGB monitor or 320 x 200, optimized for a composite monitor or television set, which a lot of home computer users still had for a display. Early in Lorraine’s development, Jay was uncertain whether or not Lorraine would have RGB video in the final product. By late 1983, he had devised a feature initially known as “hold and control” mode, later renamed Hold And Modify (HAM) to get more colors on screen.

Daphne had a control bit in the BPLCON0 register, bit 8. This enabled RGB or NTSC mode, affecting how the 12 bits of color would be interpreted. In RGB mode, color bits 0-3 are for Red, 4-7 for Green and 8-11 for Blue. In NTSC mode, bits 0-3 are for Y (Luminance), 4-7 for I (In-phase) and 8-11 for Q (Quadrature). I and Q are 90 degrees out of phase from each other and modulated together to generate a color (chroma).

Sometime after the preliminary hardware manual was written, YIQ was dropped from Daphne. However the Hold And Modify feature was kept and would later be utilized to display color photographs in high resolution. NTSC video out was reimplemented off chip. The composite and TV video on the black box are generated using two MC1496 balanced modulator chips and several resistors. A Motorola MC1377 was used for the production Amiga. Bit 8 in BPLCON0 was later reassigned to enable audio for the genlock and renamed GAUD.