Sirius a "pureblood"?

[grey_wolf_c]

No: HPFGUIDX 37206

We know for certain that James was a "pureblood" (that is, he came from 
a wizard family), that Lily came from a muggle family, that Ron's 
family is pure wizards, etc. However, I'm pretty unsure of Sirius' 
origins. Are his family wizards, muggles or both? (Please give as much 
canon as possible).

To start you out, the only canon I could recall on the matter is 
Harry's letter to Siruius at the start of GoF, in which he explains: 
(liberal translation) "[...] Dursley threw his console out of the 
window. It's a sort of computer you can play games on" (end of ch. 2, 
GoF) (as always, I'd be grateful if someone could find me the correct 
quote). 

The first time I read that, I though Sirius had to be from a wizard 
family, or wouldn't have needed explaining. However, I'm not so sure 
about that anymore. First off, Harry explains the videoconsole by using 
an analogy to a computer, which a wizard wouldn't know either, so 
Sirius would have to be from a muggle family (or at least have lived in 
the muggle world quite a bit). But then, if he knows about computers, 
why doesn't he know about videogames? The answer hit me the other day: 
Sirius has been out of contact with the muggle world 20 years (since he 
started Hogwats), and out of contact with the rest of the world for 13 
years (since he was thrown into Azkaban). This means that, when he was 
a child (10 years old or so), he could have heard about computers, but 
the first consoles didn't start to appear until 1985-1986 (at the very 
least, I think). By then, he had already been thrown into prison, so he 
wouldn't have known about it.

In conclussion, that little piece of canon seems to point towards a 
Sirius from muggle family, but it is pretty circumstancial at any rate, 
so please post your own evidence.

Hope that helps (my canon, that is)

Grey Wolf