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Speedball
ROM Mapping
Each Speedball ROM is 128KB in size and uses mapping in slot 2. That is, the first 32KB of the ROM is always mapped into Z80 address space at $0000 - $7fff [1]. The remainder of the ROM is composed of 6 banks, each 16KB in size. These banks are mapped, one at a time, into Z80 address space at $8000 - $bfff.
ROM Version Differences
The only differences between the Image Works and Virgin Games versions of Speedball are within the ROM header and the data for the initial logo screen & title screen.
In the ROM header, the two ROMs have different product codes (IW: 25009, VG: 25013) and different version numbers (IW: 0, VG: 1).
The logo screen is completely different between the two versions:
- The Image Works ROM contains (uncompressed) tile data for this screen at $1c000-$1d81f, followed by the palette at $1d820-$1d83f. The Virgin Games ROM uses fewer tiles: it contains tile data at $1c000-$1d6df followed by the palette at $1d6e0-$1d6ff. The end of the Image Works data remains, unused, at $1d700-$1d83f. In both cases, the length of the tile data is given by the word at $056f5 [2] and a (word-sized) pointer to the palette data is at $05520.
- The two versions have different name table data for the logo screen (located at $1d840-$1de3f).
On the title screen, the Image Works ROM shows "© MIRRORSOFT LTD 1990" while the Virgin ROM has "© VIRGIN GAMES 1992 ".
- ^ All address ranges on this page are inclusive.
- ^ In the Virgin Games ROM, this length is incorrectly given as $1700 (rather than $16e0) - this leads to the palette data being interpreted as an additional tile.
Researched by Paul Baker
- See the main page for Speedball
