ABOUT .IPC (ICE PCIN) ...

This is a new picture format that displays pictures using the ICE (Interlace Character Editor) mode PCIN.  This mode is related to Super IRG (used in Bill Kendrick's "Gem Drop" game) but can display 35 colors onscreen at once at 159x192 pixels.  The picture display also involves a character set change every 3 character lines, creating essentially a bitmap mode using character fonts as the screen memory.

THE VIEWER:

The viewer will load and display any .IPC file from disk.  The file format itself allows for Hi-res (Antic 4) and lo-res (Antic 5) pictures, but the viewer will currently display correctly only hi-res pictures.  You can also generate ICE font files which will then be viewable in the ICE CIN font editor.									


About PCIN ...

PCIN is an ICE mode related to Super IRG, in that a character set flip is done every VBLANK between two Graphics 12 fonts, to give the illusion of extra colors.  The GTIA register at 623 is also swapped, so that the screen cycles rapidly between Graphics 12 and Graphics 10 (the 9 color 80 pixel mode).  This allows for 30 colors per character cell, and 35 colors onscreen at once.

The colors in PCIN are divided into 9 color groups of 4 colors each (plus a fifth when using inverse characters).  Each character cell is 4x8 as in Antic 4, but every group of 2 pixels has to be of the same color group.

Group 1:  The background color group ... which blends the background with the four playfield colors.

Groups 2 to 4:  PM color groups, blending the PM color registers 705-707 with the four playfields + background

Groups 5 to 8:  Playfield color groups, which blend the four playfield registers (708-711) with each other.

Group 9:  The 9th color group, created by changing register 712 every VBLANK, this color is blended with the four playfield colors.

There are identical color pairs in the PF and BG color groups, these can be offset from each other in a dithering checkerboard pattern to reduce flicker.

.IPC format documentation

Byte #1:  Resolution ... 0=low, 1=high
          The viewer currently only supports high res (Antic 4)

Next 9 bytes:  Color palette (BG, 705, 706, 707, 708, 709, 710, 711, 9th color)

For hi-res pics (included here), are 8 sets of 2048 byte ICE fonts, collated as follows:

<Graphics 12 font> 1024 bytes
<Graphics 10 font> 1024 bytes

Following this is a 960 byte screenmap which contains 8 sequences of ATASCII 0-120 ... certain characters will be inversed where the 5th color is used in Antic 4.

For low-res pics, 4 sets of 2048 byte ICE fonts, as follows:

<Graphics 13 font> 1024 bytes
<Graphics 13.10 font> 1024 bytes

Graphics 13.10 uses a different color layout, in that color groups PM3 and PF3 can only be accessed with inverse chars.

Following this is two 480 byte screenmaps, containing 4 sequences each of ATASCII 0-120 ... with characters inversed as necessary.

Other viewers:

Viewers are planned for other ICE modes, as follows:

.DIN - Graphics 0/12 interlace, 320 pixel resolution at 10 colors
.IRG - Super IRG, 160 pixel resolution at 15 colors
.IR2 - Super IRG 2, as above but 25 colors
.ICN - ICE CIN, Graphics 11/12, as above, 16 chroma x 5 luma or 80 colors
.IMN - ICE MIN, Graphics 9/12, as above, 16 luma x 5 chroma
.IP2 - ICE PCIN+, like PCIN but at 45 colors.


		