Speeds in Boulder Dash 1

[subotai]

Thanks Logic for your reply

I see. PAL = 25 frames/second; NTSC = 29.97 frames/second. If I remember right, I already asked a similar question when "calculating" the inbox hatching. Hmm, I think that Inbox-Hatching is after 2400 milliseconds ( = 2 seconds NTSC), isn't it?

Well, as most fan games are designed for PAL machines and having more time to solve a cave is never a disadvantage, I keep the timer like this

[subotai]

I just changed my mind As I got some bits left for saving data and the game Rockford for PC (that my engine also supports) uses normal timing, I added a game specific switch for choosing between PAL and NTSC timing. Very funny to see, that Intermission 3 in BD1 gets solvable when I switch to NTSC-Timing .

Thanks again cirix for the formulas. They seem to be very good!

[subotai]

There is still one point that I don't understand. I set my focus on the timer speed, not on the game speed. But the game speed should be faster on NTSC machines, shouldn't it? I thought that Intermission 3 in Bd1 is solvable on NTSC machines. But, if the game speed is increased, the inbox hatching should take place at the same scan routine as on PAL machines. Or did I miss something?

[LogicDeLuxe]

But the game speed should be faster on NTSC machines, shouldn't it?

Only, if it isn't already on the limit, and never for BD1.

BD1 uses a simple loop using up a fixed amount of CPU cycles, the amount changes with the level. Eventhough, NTSC C64 have a slightly higher CPU clock, this benefit is counteracted by the more frequently IRQs, which take the most time in BD.

From BD2 on, the delay is given in TV fields, thus NTSC is faster as long as the cave scan can handle that speed (about 5 when little is going on, much more when much items are moving around or many active elements are present in the cave).

My XDC has a new timer, which automatically slows down if the machine can't handle the given speed, resulting in a perfectly reproducible cave behavior. It is also designed to work perfectly with turbo boards. Also XDC's game speed is more steady, since there is speedcode for the 2x2 drawing (taking the same amount of cycles for every frame) while older engines do this 2x2 drawing during movements (which has a very noticable impact on speed during heavy activity).

[subotai]

Thanks for your reply.

My XDC has a new timer, which automatically slows down if the machine can't handle the given speed, resulting in a perfectly reproducible cave behavior. It is also designed to work perfectly with turbo boards.

Sounds good