64bit data 128Bit address...Re: Building a Z-80 (64bit!

Date: Mon, 26 Oct 1998 19:41:01 +1 Reply-to: classiccmp(a)u.washington.edu From: "Hans Franke" <franke(a)sbs.de> To: "Discussion re-collecting of classic computers" <classiccmp(a)u.washington.edu> Subject: Re: 64bit data 128Bit address...Re: Building a Z-80 (64bit!

>> "Max Eskin" <maxeskin(a)hotmail.com> wrote:

The size isn't the real problem - you already get 16 Gig in less than 320 cm^3 (using hard disk technology) which is more than 100 Meg per cm^3, which gives us 100x100x100x100 Meg or 100 Tera per m^3 (Only heat will be a problem, but if we assume that this will shrink by the factor 2 within the next few years, we get enough space for cooling without developing a new technology). 100 Tera are 100x2^40 Bytes so, for 16 exabytes you need 10x2^18 m^3 or 64x64x64x10 m^3 - just the size of a ordinary 160 store skyscraper. Nothing real big - isn't it? - and especialy not a mountain. and if we assume a increasing density by 10 within the next years, it is less than a warehouse. This is all just (near) todays technology - the real problem is the access time .... A wire could come up to 100m between a starage device at the perhipherieal area and a 64 Bit computer in the middle - 100m thats just 1/3.000.000s or 333ns traveling time ... seams we have created some kind of piplineing prior to the CPU :) So, calulating a 1 us round trip time, we just could runn a 4 MHz Z80 ... hmm didn't he ask for 64 Bit Z80 ? (I just left the disc acces time out of calculation, but acording to any information availabel from disk manufacturers the internal caches will eliminate this almost to zero :) Gruss Hans