68K (ISA) project
henk.gooijen at hotmail.com
Fri Jul 16 13:32:36 CDT 2010
From: "Charles Dickman" <chd at chdickman.com>
Sent: Friday, July 16, 2010 4:59 AM
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Subject: Re: 68K (ISA) project
> Back in 1999 I had some of the same ambitions, this (
> http://www.chdickman.com/sbc/ ) was the result. Like many things, I never
> followed through with it. I could interface 68k, 6800 and Intel oriented
> ICs. I think it has all the signals necessary to add an ISA bus. I did
> some edge connectors for the purpose. I keep wanting to get it back out
> play with it.
> A monitor listing and the PLD files are online, but not a schematic. I
> wanted to put out a schematic, but I got the idea that a kid in college
> using it for a class project. Actually with PLD files should be enough to
> figure out the rest for "someone competent in the field."
Nice work Chuck.
I know your pages, but somehow I never noticed the 68k page!
*if* I am going to build another 68k SBC, it will probably not have
the 64 pin DIL 68k but the 68HC000 QFP chip you used, because
it can run at higher clock speeds.
I have my pdp8/e code transalted to 68k assember, and it runs
MAINDEC-8E-D0AB-PB.pt (instruction test pt. 1) succesfully.
Using Easy68k's cycle counter dividing by 10 MHz it seems that
this code runs approx 3x slower than a real pdp8/e.
However, MAINDEC-8E-D0BB-PB.pt (test pt. 2) fails quite
early on DCA, for which I have not yet a solution.
But it is fun to debug some 68k assembler code again :-)
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