STIC

The STIC provides the video display for the Intellivision Master Component. It is capable of displaying a background resolution of 160x96 pixels and up to 8 hardware sprites, referred to as Moveable OBjects or MOBs.

Background

The background area is rendered by the STIC as a series of "cards", which are blocks of 8x8 pixels. Thus the background is composed of 20 cards horizontally and 12 cards vertically for a total of 240 cards.

The cards to be displayed by the STIC are loaded by the program into an area of memory referred to as the BACKground TABle or BACKTAB. The BACKTAB is located within a portion of the 16-bit RAM memory space from $0200-$02EF. During each screen refresh, the STIC reads each card from the BACKTAB and draws it onscreen. How the STIC interprets each card in the BACKTAB depends on whether the STIC is in Foreground/Background mode or Color Stack mode.

Foreground/Background Mode

The program selects to have the STIC display the BACKTAB in foreground/background mode by writing to register $21 at some time during the previous vertical blank. The STIC will then interpret each value in the BACKTAB as follows.

     15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
      ?  ?  B  b  t  b  b  n  n  n  n  n  n  f  f  f

   where:
     bBbb      is the background color (off bits), either pastel or primary colors (0 - 15)
     t         is a toggle which tells the STIC where to grab the card from:
                   0 = GROM, 1 = GRAM
     NNnnnnnn  is the actual # of the card corresponding to it's position in GRAM or
               GROM, (0 - 63) or (0 - 212).  The top two bits (NN) are only used when
               plotting a GROM card, so for a GRAM card you can use them as user-defined
               flags
     nnnnnn    is the actual # of the card corresponding to it's position in GRAM or
               GROM, (0 - 63).
     fff       is the foreground color, primaries only (0 - 7)

Moveable Objects

The STIC is capable of rendering up to 8 moveable objects, or MOBs, which may be either 8x8 or 8x16 in size. The STIC can stretch each MOB horizontally by 2x, and can stretch each MOB vertically by 2x, 4x, or 8x. Note that each MOB pixel is displayed by default (if no stretching is enabled) as the same width of each background pixel, but only half the height of the background pixels. The STIC can also mirror each MOB in the horizontal direction, the vertical direction, or both.