One trick I've struggled with figuring out in video games is how enemies "walk" around the walls, floors and ceilings. Like the enemies in Cybernoid II that crawl along. I feel it's something that looks complicated but actually simple.
Usually it is as simple as using a recorded animation with suitable rotated sprite frames. Sometimes there will be a marker indicating a corner, other times the routine will just detect a wall or ceiling and move the object accordingly. Moving up or down a wall is really no different to the floor or ceiling, just detect different edges.
I did a quick binary compare of the C64 and Spectrum memory. There are a few hundred bytes of data in the middle of memory that are the same (it looks like a table) but most of it is quite a lot different. Not really enough to conclusively say there is significant data sharing. When I've been stepping through the code I get the feeling it's been written by hand, not blindly ported from Z80.
I would have said a conversion, not a port, so it's also quite possible both were written at the same time. The specky was the lead by its limits or rather by its design, and then it was just coded to fit the task. Few people would have hand translated z80 code in 6502 as it was a skill set not often needed; either you are one or the other. One of my games I had the listing of the arcade original, but frankly completely pointless, as zero comments, and also was Japanese spegetti code anyhow! 😄
Great video and result - as always. Do you think you could retro-fix the small glitchy split screen scroll in the original Gribblys Day Out? Love your work.
One trick I've struggled with figuring out in video games is how enemies "walk" around the walls, floors and ceilings. Like the enemies in Cybernoid II that crawl along. I feel it's something that looks complicated but actually simple.
Usually it is as simple as using a recorded animation with suitable rotated sprite frames. Sometimes there will be a marker indicating a corner, other times the routine will just detect a wall or ceiling and move the object accordingly. Moving up or down a wall is really no different to the floor or ceiling, just detect different edges.
This has to be a direct port of a ZX Spectrum game.
I did a quick binary compare of the C64 and Spectrum memory. There are a few hundred bytes of data in the middle of memory that are the same (it looks like a table) but most of it is quite a lot different. Not really enough to conclusively say there is significant data sharing. When I've been stepping through the code I get the feeling it's been written by hand, not blindly ported from Z80.
I would have said a conversion, not a port, so it's also quite possible both were written at the same time. The specky was the lead by its limits or rather by its design, and then it was just coded to fit the task.
Few people would have hand translated z80 code in 6502 as it was a skill set not often needed; either you are one or the other. One of my games I had the listing of the arcade original, but frankly completely pointless, as zero comments, and also was Japanese spegetti code anyhow! 😄
Great video and result - as always. Do you think you could retro-fix the small glitchy split screen scroll in the original Gribblys Day Out? Love your work.
I can try and have a look :)