The 1980s were the heyday of the venerable Z80, a processor that found its way into innumerable home computers, industrial systems, and yes — arcade machines. However, not everyone had a Z80 based machine at home, and so sometimes porting is required. [Glen] is tackling this with a port of Pac Man to the Radio Shack Colour Computer 3.
The key to any good arcade port is authenticity – the game should feel as identical to the real thing as possible. The Atari 2600 port got this famously wrong. Porting to the Colour Computer 3 is easier in theory – with more RAM, a Motorola 6809 CPU running at a higher clock rate, and a more powerful graphics subsystem, fewer compromises need to be made to get the game to run at a playable speed.
The way [Glen] tackled the port is quite handy. [Glen] built a utility that would scrape a disassembled version of the original Pac Man Z80 code, look up the equivalent 6809 CPU instruction, and replace it, while placing the original Z80 code to the side as a comment. Having the original code sitting next to the ported instructions makes debugging much easier.
Overall, the port is highly faithful to the original, with the game code being identical at the CPU level. [Glen] reports that the same patterns used on the arcade machine can be used to complete the mazes on the Colour Computer 3 version, and it faithfully recreates the Level 256 bug as well. It’s an impressive piece of work to create such an authentic port on a home computer from 1986.
For another classic port, but with the temporal vectors flipped, check out Portal 2 on the Apple II.
In the digital version of the game, the tokens conveniently display a number representing their total power value. [Martin] liked this feature, and set out to design a replacement token for the tabletop version that could display a number while still keeping the aesthetic of the originals. The tokens were designed as a dial with a small cutout window to show a number, but the surface of the token showing color and icon is still mostly unchanged.
