20 Nov
2007
20 Nov
'07
10:36 a.m.
Subject: Re: *updating* 8088's
From: Dave McGuire <mcguire at neurotica.com>
Date: Tue, 20 Nov 2007 11:43:02 -0500
To: "General Discussion: On-Topic Posts Only" <cctech at
classiccmp.org>
On Nov 19, 2007, at 11:03 PM, Allison wrote:
I meant 6MHz, 12mhz crystal. However, even at 6 its fast.
FYI I tried overclocking a 80C856mhz part and it was still
doing well at 8mhz but I was seeing memory timing issues.
You don't see the 6mhz parts too often. The usual is the
3 and 5mhz and usually the -5 (5mhz) will overclock to 6
with no real issues.
At those speeds it's intereating as old 8080 software is
now at 3X!
Though a 10mhz Z80 is also a nice thing but the 85nS memory
need is something to aware of. That short M1 read cycle
preally beats up ram. Z180 is better and Z84S180s can be
found as fast as 33mhz.
Allison
I build with 6 and 10mhz z80s and 12mhz 8085s I
have and theres
little problem with finding static rams and Eprom (and EEprom)
that can keep up.
Did you say 12MHz 8085? Holy cow! Tell me more?
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
21 Nov
21 Nov
12:32 a.m.
On 20 Nov 2007 at 13:36, Allison wrote:
I meant 6MHz, 12mhz crystal. However, even at 6 its
fast.
FYI I tried overclocking a 80C856mhz part and it was still
doing well at 8mhz but I was seeing memory timing issues.
A third-party 8MHz 80C85 existed, the Tundra CA80C85B-8CP. Here's a
databook for it:
http://www.datasheetarchive.com/pdf/972187.pdf
The nice thing is that they document the "undocumented" 8085 opcodes,
calling them "extended". They don't mention that the original Intel
8085 had the same features...
I've never had a Tundra part in my hellbox.
Cheers,
Chuck
12:56 p.m.
Chuck Guzis wrote:
On 20 Nov 2007 at 13:36, Allison wrote:
I don't remember the 8085
having the same extended opcodes.
I meant 6MHz, 12mhz crystal. However, even at 6
its fast.
FYI I tried overclocking a 80C856mhz part and it was still
doing well at 8mhz but I was seeing memory timing issues.
A third-party 8MHz 80C85 existed, the Tundra CA80C85B-8CP. Here's a
databook for it:
http://www.datasheetarchive.com/pdf/972187.pdf
The nice thing is that they document the "undocumented" 8085 opcodes,
calling them "extended". They don't mention that the original Intel
8085 had the same features...
I've never had a Tundra part in my hellbox. Chuck
PS. Checks the web. Tundra is still around
but they offhand don't seem
to selling 80C85's anymore.
1:23 p.m.
On 21 Nov 2007 at 13:56, woodelf wrote:
I don't remember the 8085 having the same extended
opcodes.
PS. Checks the web.
I went to Tundra's site initially, only to find their 80c85 in the
"discontinued, no information" list.
But I might as well reply "check the web":
http://electronicerror.blogspot.com/2007/08/undocumented-flags-and-
instructions.html
The standard "undocumented" 8085 opcodes are exactly the same 10
described by the Tundra document as "extended instructions" (I don't
count RIM and SIM--they've always been documented for the 8085).
They've been mentioned at least a couple of times on this list also.
The upshot of all of this is that Tundra "implemented" nothing except
documentation of instructions that were always present. It would not
surprise me to find that they licensed the mask from Intel all along.
Cheers,
Chuck
26 Nov
26 Nov
6:36 p.m.
On Nov 20, 2007, at 1:36 PM, Allison wrote:
Though a 10mhz Z80 is also a nice thing but the 85nS
memory
need is something to aware of. That short M1 read cycle
preally beats up ram. Z180 is better and Z84S180s can be
found as fast as 33mhz.
I've done quite a bit of work with the eZ80F91 at 50MHz. Running an
RTOS with a TCP stack...still quite zippy. I use 15ns RAM in my
designs, Cypress CY7C1049CV33-15.
-Dave
--
Dave McGuire
Port Charlotte, FL
6019
days inactive
6026
days old
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