----- Original Message -----
From: "Joao Paulo Samara" <joao.samara_at_p...>
>
> -----Original Message-----
> From: Murilo Saraiva de Queiroz [mailto:murilo_at_v...]
>
> >Muriloq (que sempre se impressiona com a confusão que se faz quando o
> >assunto é "videogueime de tantos bites")
>
> Falou e disse Murilo!
> E falando nisso: existe algum vídeo game com registradores
> de uso geral de 64 bits? Porque o "pessoal do marketing" adora
> ficar inventando máquinas de mais de 32 bits e fora os
> Alphas, Sparcs, Itanium's, Cray's e SGIs, (e alguma que estou
> esquecendo) não conheco nenhum comp ou vídeo game que
> tenha registradores de uso geral de mais de 32bits.
>
> []'s
>
> JP.
>
Todos os vídeogames modernos usam registradores de uso geral de 32 bits
(PS2, Jaguar, Nintendo 64, X-Box. ...). Mas é comum encontrar em chipsets
gráficos barramentos e instruções que operam em registradores muito maiores
(64 bits no Jaguar, 128 no PS2, etc.).
Eu particularmente gosto do ponto de vista encontrado no faq abaixo.
http://www.myatari.net/issues/jan2001/jag_faq.htm
The question is hard to resolve, largely because the definition of what
constitutes an "N-bit" system has not been set. Of the five processors in
the Jaguar, only the object processor and the blitter are "true" 64-bit
components. Because the blitter and the object processor are in the Tom
chip, by extension Tom is a 64-bit chip. Furthermore, the Jaguar also used a
64-bit memory architecture, according to Jez San of Argonaut Software.
Some say the Jaguar should be considered a 32-bit system, as that is the
maximum register size in the programmable processors (the 68000, the
graphics processor, and the DMA sound processor). Others say the Jaguar can
be considered a 64-bit system, because 64-bit components are used, and the
GPU can access 64 bits of data if required. Again, the lack of an
agreed-upon definition serves to complicate the issue.
According to Jaguar designer John Mathieson, "Jaguar has a 64-bit memory
interface to get a high bandwidth out of cheap DRAM. ... Where the system
needs to be 64 bit then it is 64 bit, so the Object Processor, which takes
data from DRAM and builds the display is 64 bit; and the blitter, which does
all the 3D rendering, screen clearing, and pixel shuffling, is 64 bit. Where
the system does not need to be 64 bit, it isn't. There is no point in a 64
bit address space in a games console! 3D calculations and audio processing
do not generally use 64-bit numbers, so there would be no advantage to 64
bit processors for this.
"Jaguar has the data shifting power of a 64 bit system, which is what
matters for games, so can reasonably be considered a 64 bit system. But that
doesn't mean it has to be 64 bits throughout."
For the record, the opinion of most third party developers and observers is
that the Jaguar is indeed a 64-bit system. The emphasis is on the word
"system"; while not every component is 64 bits, the Jaguar architecture, as
a COMPLETE SYSTEM, is.
Recebida em Tue 31 Dec 2002 - 01:02:26 BRST