Game Boy
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Pontifice
Learning
I think conditional RETs have different cycle length if it is done or not ( writing in the stack or not) and the same for conditional CALLs.
With conditional JRs i'm not sure because Z80 could read the displacement before checking the condition, but why some designer will lost time doing nothing when speed was ( is ) so important at that level.
With conditional JRs i'm not sure because Z80 could read the displacement before checking the condition, but why some designer will lost time doing nothing when speed was ( is ) so important at that level.
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Soccr743
Cubed Member
I checked the Gameboy PDF that I got from a zip in this post, and it says that there are 12 cpu cycles used for CALL nn and also for CALL cc,nn. So infact the cycles stay the same even when a condition check is required.
The same goes for RET and JR as well.
-----Soccr743----
The same goes for RET and JR as well.
-----Soccr743----
Dark Stalker
New member
In case anyone's still interested, I've decided to make a sort of binary-only "technical preview" release. There's absolutely no usability features whatsoever. In other words, no gui, configuration, or speed-syncing (simply because I've not cared to implement any of those yet). If you want to enjoy playing games, this isn't for you. The compatibility has gotten quite good by now, if I may say so myselfzenogais said:
. Still no sound though. As for speed, the emu is currently slow, but it should be fast enough to run a few times faster than the real GB on a modern PC. I mean to remedy this later of course.The emu doesn't really have a name yet, but it's been dubbed "lameboy" during development.
The win32 version is really ugly btw., since it's a direct, violent, unfitting port of the command-line linux version. To use it, just "drag and drop" a romfile onto the lameboy.exe icon, or associate the gb-filetype with lameboy.exe, or just pass the romfile as a parameter to lameboy.exe (using cmd, run, or a shortcut).
For the linux version you need to have libsdl>=1.2 installed (should be in your distros package-repository). To use it, just give the romfile as a parameter to lameboy (./lameboy <romfile>). The linux version has been compiled with two different versions of g++ for compatibility with libstdc++.so.5.
edit:
Just thought I might mention the keyboard controls:
Return = Start
Right Shift = Select
Key 'D' = Button A
Key 'C' = Button B
Download links:
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ShizZy
Emulator Developer
Nice, Dark Stalker.
@bcrew, I was just checking some things and spotted an error in your code. On SLA, you're reseting flags Z and C, when you should be reseting H and N. I'm sure it's just a typo, but just thought I'd point it out if you havn't corrected it yet. (Not that it'd make a whole hell of a difference anyways)
Anyways, a few more things I want to tack on, and I'll post my current cpu source tonight. Timings and interrupts are pretty much nonexistent, but other than that I have a good chunk of coding done.
@bcrew, I was just checking some things and spotted an error in your code. On SLA, you're reseting flags Z and C, when you should be reseting H and N. I'm sure it's just a typo, but just thought I'd point it out if you havn't corrected it yet. (Not that it'd make a whole hell of a difference anyways)
Anyways, a few more things I want to tack on, and I'll post my current cpu source tonight. Timings and interrupts are pretty much nonexistent, but other than that I have a good chunk of coding done.
Not exactly. I'm ANDing the flags register with FLAG_Z_ON and FLAG_C_ON, which are the values 0x80 and 0x10, respectively. So, I'm turning off flags H and N(That actually could make a big difference depending on the game. Thanks for that, though . That source is pretty outdated, I've made quite a few changes since then. There's a bug in the LY register updating that I can't seem to fish out. I'm almost certain it has to do with incorrect timing. Could someone run a test on Earthworm Jim for me? I need to know the value of the Program Counter when LY goes from 0 to 1 for the first time. Anyway, here's the updated source. I haven't really checked it... at all. So, it might have some really messed up stuff in it.
. That source is pretty outdated, I've made quite a few changes since then. There's a bug in the LY register updating that I can't seem to fish out. I'm almost certain it has to do with incorrect timing. Could someone run a test on Earthworm Jim for me? I need to know the value of the Program Counter when LY goes from 0 to 1 for the first time. Anyway, here's the updated source. I haven't really checked it... at all. So, it might have some really messed up stuff in it.
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Yes, it helped a great deal, thank you very much! With that information, I solved my Earthworm Jim and Super Mario Land 2 problems! :happy: SML2 freezes before the first level at the moment, but that should be nothing now that I solved that problem(Which I'd rather not mention, as it's pretty embarassing :blush:.) Once again, thank you, aprentice. That's been a plague on me for weeks!