Monitor for iSBC 8024

From: ajp166 <ajp166_at_bellatlantic.net>
Date: Sat Nov 4 11:24:08 2000

From: Richard Erlacher <richard_at_idcomm.com>


>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


This is true. It is a larger cpu.

>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


To be exact the z80 has

    A A' 8BIT
    BC BC' 16BIT
    DE DE' 16BIT
    HL HL' 16BIT
    IX 16BIT
    IY 16BIT
    SP 16BIT
    F F' ~8BIT FLAGS
    PC 16BIT
    I 8BIT (HIGH 8BITS OF INTERUPT VECTOR)
    R 8BITS (REFRESH ADDRESS)

6502
     A 8BIT
    X 8BIT
    Y 8BIT
    PC 16BIT
    SP 9BIT (HIGH BIT =1)
    STATUS 8BIT

Big difference in the number of bits for storage alone. It accounts for
most of the
die area (ram/registers that is).

>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.


8080 is not near as efficient in logic usage as z80.

The different is in memory vs register usage in programming. A
reasonably
complex 6502 program will always use more ram than similar in z80 if only
due to need for multiple pointers, local storage and parameter passing.

A while back I said I passed on an cmos ASIC project that was going to
use 8088 (actually 80186 core) as a embedded app. the client insisted
on it and planned to inegrate 32-64k of rom and at least 4-16k of ram
with
it. Application, remotely read peaking power meter. People do this!

Compared to the 80186 core the z80 is tiny!

Allison
Received on Sat Nov 04 2000 - 11:24:08 GMT