Monitor for iSBC 8024

From: Richard Erlacher <richard_at_idcomm.com>
Date: Sat Nov 4 09:43:10 2000

Pleasesee embedded remarks below.

Dick

----- Original Message -----
From: Mike Cheponis <mac_at_Wireless.Com>
To: <classiccmp_at_classiccmp.org>
Sent: Saturday, November 04, 2000 12:17 AM
Subject: Re: Monitor for iSBC 8024


> Just some data; sometimes data helps.
>
> Year Chip #transistors Die Size
> ---- ---- ------------ --------
> 74 8080 4,800 20 mm^2
> 75 6502 4,000 21 mm^2
> 76 Z80 8,500 18 mm^2
>
> -Mike C

That's interesting! I was comparing the quoted sizes of a couple of HDL
versions available on the web. The smalles 650x I found was about 3200
gates, while the smallest Z80 was listed at 9200. It's difficult to say
whether that's the actually-used gate count, or whether it's the gates used
as a consequence of the implementation. If a logic cell is used, regardless
of how much of that LC is used, the "gates" contained within it are gone,
whether it's a nand gate or an adder, or whatever.

The counts listed within an IP item description usually are reflective of
what's used rather than what's consumed, so it can be quite misleading.
Sometimes they specify how many cells it uses in a given array series, which
gives a better count of consumed resources if one's looking to use that
particular family. If one wishes to use something else, however, it's
tempting to use the number of cells x the number of gates each cell
represents, which is often "optimistic" with respect to what's likely to be
the actual result of a fit.

Eric Smith reminded me some weeks back that the Z80 has two complete
register sets, which pretty quickly leads me to conclude it's justified in
consuming considerably more resources in an array than the 650x core. One
might conclude that the 8080 should lie between the two, since it has more
registers than the 650x, yet fewer than the Z80. The transistor count is
not quite reflective of the register resources, but it does appear that the
8080 has more transistors used than the 650x.

>
> On Fri, 3 Nov 2000, ajp166 wrote:
>
> > From: Richard Erlacher <richard_at_idcomm.com>
> >
> >
> > >The Z80 core is about three times the size of the 650x core and really

<snip>
Received on Sat Nov 04 2000 - 09:43:10 GMT