TheNameOfTheGame wrote: ↑
Mon Dec 25, 2017 3:52 pm
Hmmm, maybe it is from running in an emulator at 32Mhz then. I tried the same game Doodlebug on my T28 on real hardware and it ran really good.
Steem for example, 32 MHz runs entire emulation four times faster. In the real world, you cannot accelerate ST-RAM speeds and it remains 100%.
ROM speeds run at around 300% at 32MHz, the CPU can run at full speed along with the ROM. In terms of ram, this cannot be accelerated runs at 100%. In terms of games the majority of game speed is dependent on ram access speed. This is why you only mostly see speedups with 3-D games as they use a lot of int-div type maths functions which the CPU can run at 32Mhz. Though unfortunately, reading and writing the values slow it down no end so you only end up with about 25% speed boost overall.
In terms of GEM and desktop stuff /apps, which heavily rely on ROM , this runs a lot faster the CPU spends more time accessing ROM and RAM. Of course it really depends on instructions and code being run. The raw speed of ROM access is about 300%, technically it should be 400%, but of course some of the test loop has to run in RAM which slows it all down.
If the same test was done with ram running at 200% speed, then the ROM access speed would be 300% + 100% about due to faster ram access. The ROM itself does not actually run any faster, but the coach testing the loop doors as it partly runs in ST-RAM. Again if it ST ram run at double speed again you would get, 300% +100% +100% = 500%. Again this does not mean ROM actually runs at this speed but this is what the benchmark will show. Of course the loop runs faster overall, so it is not like the benchmarks are inaccurate.
As for the T28, assuming this has cache ? Then ST-RAM in parts are running in the cache RAM at 28Mhz. So some instruction loops get accelerated a lot. In this respect, this is why the 030 CPU is better, as it is a more efficient core, and has data and instruction caches which can run very fast. Though of course a side effect of this is that things start have compatibility issues with the new CPU etc.
The work I am doing, is to keep everything using a 68000 core and to max it out as much as possible. This will keep compatibility to a maximum, of course things like demos or any code is timing dependent isn't going to work. That is the price you pay for extra speed.