Re: [Qemu-devel] [PATCH] Z80 emulation updated again!

[Alexander Graf]

On 21.12.2010, at 12:14, Artyom Tarasenko wrote:

> On Tue, Dec 21, 2010 at 10:25 AM, Alexander Graf <address@hidden> wrote:
>> 
>> On 21.12.2010, at 02:24, Andreas Färber wrote:
>> 
>>> Am 21.12.2010 um 01:10 schrieb Alexander Graf:
>>> 
>>>> On 21.12.2010, at 01:06, Andreas Färber wrote:
>>>> 
>>>>> Am 20.12.2010 um 23:45 schrieb Alexander Graf:
>>>>> 
>>>>>> On 31.05.2009, at 17:20, Stuart Brady wrote:
>>>>>> 
>>>>>>> Here's an update of the Z80 system emulator, which currently emulates
>>>>>>> the ZX Spectrum only. [...]
>>>>>> 
>>>>>> [...] do you think it's a valuable target to have in upstream qemu?
>>>>> 
>>>>> The z80 was also used in the more modern TI-83 Plus programmable 
>>>>> calculator [1], for instance
>>>> 
>>>> The general I/O framework is heavily geared towards server and desktop 
>>>> use. The main use case of the Z80 that I'm aware of is the GameBoy. Not 
>>>> sure that one fits in there too well :).
>>>> 
>>>> The Spectrum however does fit the desktop case, so it certainly has my 
>>>> blessings.
>>> 
>>> Knowing the ZX Spectrum only from the attic, I agree that emulating game 
>>> consoles is not the primary purpose or strength of QEMU.
>>> (Although I wouldn't mind if someone wanted to contribute a PS3 machine for 
>>> Cell B.E. emulation!)
>>> 
>>> Fwiw mips, arm, m68k, cris, microblaze seem to form a growing third 
>>> category of QEMU targets though, embedded systems.
>> 
>> Oh, sure. I'd count in embedded systems here too. My main point was that we 
>> don't have frameworks to deal with Joysticks, 3D or other stuff real game 
>> system emulation would need.
> 
> With the emulation of the ancient machine based game platform it is
> even more complicated: games expect some certain timings from the CPU,
> graphic and sound cards. So, I'm not sure if TCG can be used for it.

Yup, old ones probably won't work. More recent ones should. Uli actually did 
create a GBA emulator using TCG a few years back, so it definitely does work 
for some stuff. I'm fairly sure that the more recent the systems become, the 
more event driven they also are - which is good for dynamic recompilation.

Either way, those really don't belong inside the Qemu source tree IMHO as 
development models don't match in general. Instead, a libtcg would be a lot 
more fitting for those cases.


Alex