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#71
Done it. 
Zilog Z84C0020PEG in CPC.
Basically it consumes no energy. It is cold.
According to the documentation, at 4MHz it consumes 20mA or 0.1W.
BASIC works.
keyboard works.
GOTEK works.
CPM works.
Bomb Jack works.
Sound works
some undocumented instructions Z80 works.
I checked LD A,LY
v%=0:CALL &BFF8,&C912,0,&7DDD,@v%:PRINT v%
246
(LD A,LY : NOP: NOP: LD (DE),A : RET)
Pinball Dream without synchronization and bad noise screen
AY3 only produces noise.
Batman Forever many scenes don't work.
AY3 only produces noise.
The relay to the tape recorder is ticking.
That's all for now.
Zilog Z84C0020PEG in CPC.Basically it consumes no energy. It is cold.
According to the documentation, at 4MHz it consumes 20mA or 0.1W.
BASIC works.
keyboard works.
GOTEK works.
CPM works.
Bomb Jack works.
Sound works
some undocumented instructions Z80 works.
I checked LD A,LY
v%=0:CALL &BFF8,&C912,0,&7DDD,@v%:PRINT v%
246
(LD A,LY : NOP: NOP: LD (DE),A : RET)
Pinball Dream without synchronization and bad noise screen
AY3 only produces noise.
Batman Forever many scenes don't work.
AY3 only produces noise.
The relay to the tape recorder is ticking.
That's all for now.
#72
I'm not aware of any CPC games that use triple buffering, are there?
I am doing the exact same thing as abalore; I have a front buffer, a back buffer and a clean buffer for restoring the background. I guess we both independently concluded this was fastest.
I am doing the exact same thing as abalore; I have a front buffer, a back buffer and a clean buffer for restoring the background. I guess we both independently concluded this was fastest.
#73
Quote from: andycadley on 21:11, 23 April 24Ok, so it's the Rhino in Sabre Wulf, as well as issues with Ghost and Goblins and speed lock games, but the principle is the same: emulating this stuff actually makes a difference some times.Quote from: Prodatron on 21:06, 23 April 24Is there any reason why you should know about these undocumented bits in the F-register beside to develop a 100% correct Z80 emulator?On the Spectrum, at least, the werewolf goes in the wrong direction if you don't emulate them correctly. Apparently a programmer accidentally took advantage of them.
I never understood why this was necessary to know. Does it have any advantages for making code better/faster/shorter? Does anyone have an example for this? Or is this just for fun (which includes detecting, if a Z80 emu is cool or not).
http://z80.info/z80info.htm
#74
Quote from: Prodatron on 21:06, 23 April 24Is there any reason why you should know about these undocumented bits in the F-register beside to develop a 100% correct Z80 emulator?On the Spectrum, at least, the werewolf goes in the wrong direction if you don't emulate them correctly. Apparently a programmer accidentally took advantage of them.
I never understood why this was necessary to know. Does it have any advantages for making code better/faster/shorter? Does anyone have an example for this? Or is this just for fun (which includes detecting, if a Z80 emu is cool or not).
#75
Is there any reason why you should know about these undocumented bits in the F-register beside to develop a 100% correct Z80 emulator?
I never understood why this was necessary to know. Does it have any advantages for making code better/faster/shorter? Does anyone have an example for this? Or is this just for fun (which includes detecting, if a Z80 emu is cool or not).
I never understood why this was necessary to know. Does it have any advantages for making code better/faster/shorter? Does anyone have an example for this? Or is this just for fun (which includes detecting, if a Z80 emu is cool or not).
#76
Muchas gracias, César!
#77
https://theretrohour.com/amstrad-cpc-40th-anniversary-with-roland-perry-pt-1-the-retro-hour-ep425/
Join us on a special journey back in time with Roland Perry, the visionary tech consultant behind the legendary Amstrad CPC, as we celebrate 40 incredible years of this iconic machine. In this not-to-be-missed episode, Roland takes us from his early days tinkering with electronics in school, through the founding of Ambit International, right up to his crucial role in steering the Amstrad CPC to success against heavyweights like the ZX Spectrum and Commodore 64.
Join us on a special journey back in time with Roland Perry, the visionary tech consultant behind the legendary Amstrad CPC, as we celebrate 40 incredible years of this iconic machine. In this not-to-be-missed episode, Roland takes us from his early days tinkering with electronics in school, through the founding of Ambit International, right up to his crucial role in steering the Amstrad CPC to success against heavyweights like the ZX Spectrum and Commodore 64.
#78
Code Select
bit 7 6 5 4 3 2 1 0
flag SF ZF YF HF XF PF NF CF
Bits 5 (YF) and 3 (XF) correspond to undocumented flags.
YF flag: A copy of bit 5 of the result.
XF flag: A copy of bit 3 of the result.
http://www.myquest.nl/z80undocumented/
It seems that in practice, on old NMOS Z80, they should follow this behavior pattern. But it is recommended not to base our programs on undocumented features because the current replacement 84C00 CMOS Z80 probably does not meet them.
#79
Copilot from Microsoft Edge say: 
The Flag Register (also known as the F register) in the Z80 processor is an 8-bit register that stores information about the results of the last operation performed. Each bit in the flag register represents a specific flag. Here is a description of each bit:
The Flag Register (also known as the F register) in the Z80 processor is an 8-bit register that stores information about the results of the last operation performed. Each bit in the flag register represents a specific flag. Here is a description of each bit:
- Bit 7 (S - Sign Flag): Set to 1 when the result of an operation is negative.
- Bit 6 (Z - Zero Flag): Set to 1 when the result of an operation is zero.
- Bit 5 (5 - Flag 5): A replica of the fifth bit of the accumulator (or result).
- Bit 4 (H - Half Carry Flag): Set to 1 when there is a half carry (or borrow) between bits 3 and 4 during addition or subtraction operations.
- Bit 3 (3 - Flag 3): A replica of the third bit of the accumulator (or result).
- Bit 2 (P/V - Parity/Overflow Flag): Set to 1 when the result of an operation has even parity (for logical operations) or when there is an overflow (for arithmetic operations).
- Bit 1 (N - Add/Subtract Flag): Set to 1 when the last operation was subtraction.
- Bit 0 (C - Carry Flag): Set to 1 when there is a carry (or borrow) from the most significant bit during addition or subtraction operations.
#80
im testing now 