[Aug/31/97]

INVINCO / HEAD-ON 2 (Sega/Gremlin, 1980)

Invinco/Head-On 2 runs on a two-board set, consisting of a main board 
and a sound board.  Power requirements are +-5V, as well as +-12V, the
-12V being used for the sound board.  

This is an interesting set of ROMs - it's actually two games in one, 
selectable by the player before pressing START.  One game, Invinco,
has been found in dedicated form on an earlier set of hardware, and 
the other game, Head-On 2, was presumably also available on an earlier
board.   

The main board is the standard "Dual Game VIC" board (assy no. 800-0058), 
with the 40-pin custom DIP marked "315-0042", or the "Extended ROM Video 
Logic" board (assy no. 800-0032), with no custom parts.

ROM (and PROM) locations and functions appear to be interchangeable
between the two variants, and at least two other games (Pulsar and 
Carnival) are known to run on this hardware platform.  Note that though
the checksum for the color PROM at U49 is identical to that of Pulsar, 
the ROM data itself is different.

Either board may be strapped for 2708s, 2516s, 2716s, 2532s, or 2732s.  
The ROMs in this archive were read from a set of 2708s.  The board's 
address decoding is convenient in that ROMs are mapped sequentially 
by part number into memory, making it easy to concatenate the 2708-based
dumps into ROMs for whatever strapping your board happens to use.

I've never seen the sound board for this game, so I have no information
on the sound board.

 PartNum.Loc  Cksm  Type
------------  ----  ----
316-0206.u14  0c8d  MMI 6331-1J / IM5610CPE / 32x8 bipolar PROM
316-0287.u49  12a0  MMI 6331-1J / IM5610CPE / 32x8 bipolar PROM
    271b.u33  89a1  2708
    272b.u32  d246  2708
    273b.u31  b497  2708
    274b.u30  5eaa  2708
    275b.u29  a46d  2708
    276b.u28  8b7f  2708
    277b.u27  bce8  2708
    278b.u26  d509  2708
    279b.u8   b1dd  2708
    280b.u7   58a9  2708
    281b.u6   fbb9  2708
    282b.u5   a317  2708
    283b.u4   8ba9  2708
    284b.u3   d65e  2708
    285b.u2   8f2e  2708
    286b.u1   24ce  2708

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