From: * (Neil Gall)

There's only really two parts all the way through:
(this is from memory, and I only just learnt it the other day)

Intro, and chorus:

E|--------------------------------------|
B|--------------------------------------|
G|--------------------------------------|
D|--------------------------------------|
A|--5---5p3---3-5-5---5-x-5p3---3-------|
E|----------5-----------------5---------|

E|--------------------------------------|
B|--------------------------------------|
G|--------------------------------------|
D|---------------5------5p3---5-5-5p3---|
A|--5--5p3---3-5------------5---------5-|
E|---------5----------------------------|

Then the verse, which is: (all 5th/power chords)

D .... (weird bass riff) .... C C Bb C

For the solo I just play lots of repeating riffs
in D - that's a fair approximation to the Tony Iommi
lead.  I wouldn't try to copy it exactly; I couldn't
do it justice, and I'm not into learning solos note
for note anyway.

As for the key, I learnt to play it in in Db (my guitar
was tuned way sharp for some reason), I think it should
be in D, but our bass player wants to play it in E.
Its a magic song which sounds good in any key :-)