68020 + 68881
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Author:  Plasmo [ Fri Dec 08, 2017 2:15 pm ]
Post subject:  Re: 68020 + 68881

I was googling for IDE68K and stumbled across this discussion. I have a question about how to interface IDE68K to the real hardware. Was there documentation on the Flite board about interfacing to IDE68K?

The links to your pictures are broken. Can you provide updated links? I had a uCOS2 class many years ago but didn't have the chance to practice it. I'm interested in getting uCOS to run on my board.

Author:  hancock [ Fri Dec 08, 2017 6:27 pm ]
Post subject:  Re: 68020 + 68881



I did not post any pictures; if the links to the Websites are broken then this is probably due to the many years passed since 680x0 is completely outdated and I am not having any more information on them.

Although I have still boards and schemes and source code lying around, I am no longer playing around with it.
Last thing I did was a simulator of one of my boards with Easy68k, but did not finish it.

Too legacy (unfortunately)


Author:  Plasmo [ Fri Dec 08, 2017 10:19 pm ]
Post subject:  Re: 68020 + 68881

Hi hancock,
I was thinking of wentworth's posts in this threads with many pictures of his "lab". Like you said, these are pretty old posts and his photobucket account may have changed. I hope he will check back soon.

68000 is definitely old, almost 40 years old now, but it has plenty of registers, a linear memory model, and an orthogonal instruction set. It is a classic & classy processor still well served as a teaching tool. Nowadays the 68000 and peripherals can be purchased cheaply in the grey markets like eBay. I think a low cost 16/32-bit SBC based on 68000 can be built. It certainly won't have the performance of Pi 3 or even the faster Arduino, but these highly integrated hardware are so hard to probe, debug and understand. The less integrated 68000 SBC is simpler and cheap enough for probing and tinkering.

Yes, software apps are lacking, but there are CP/M 68K, uCLinux, uCOSii, etc with languages like C, Basic, and Pascal. IMHO, it is still a pretty big sand box to play in.


Author:  profkelly [ Sat Dec 09, 2017 12:36 pm ]
Post subject:  Re: 68020 + 68881

The 68000 is an excellent choice for teaching assembly language and computer architecture for a number of reasons. There is a wealth of information and example programs available. The architecture is easy to understand yet still offers a powerful instruction set. It doesn't matter that the chip is old or out of production. The purpose of teaching assembly language and computer architecture is not to prepare the student for a career writing assembly code. The purpose is to make them a better programmer by giving them a better understanding of how computer programs interact with the CPU and hardware. Assembly language programming is so different from the programming most students have done that it forces them to think about programming in a different way and that makes them a better programmer.

Author:  hancock [ Sat Dec 09, 2017 6:57 pm ]
Post subject:  Re: 68020 + 68881

@Plasmo and ProfKelly,

please don't get me wrong: I still LOVE the m680x0-family and enjoy thinking about my projects. That is also why I am keeping my boards and some Mac LCs (68030)
I got the CP/M68k running within Easy68k (just could manage to read the floppy-dumps completely), tried to port Linux/68k to my boards, did lot's of Eprom-Programming (firmware) and many other stuff.

Today, everything you could think about implementing on such a low level (hardware near, which is my preferred level) has already been done, for every new board you get immediately an entire Linux-port as if this was nothing.

I find this very discouraging which is why I abandoned low-level programming and my projects, although I would not exclude taking this matter up again one day - the temptation is still there...
For newcomers this is obviously a fantastic way to start (but should you not go to Raspberry or the like?)

And Easy68k such a great tool for the purpose although they did not have the energy to implement the 68030/882-instructions for probably the same reasons :-)
IDE68K supports this but is by far not so comfortable...

Should you get CP/M further than me, I would be happy to solve my floppy problems (it was a matter of track translation stuff...

....hmm, no, better, whenever you have code to share, I would happily take a look at it and play around! :-)


Author:  Plasmo [ Sun Dec 10, 2017 3:50 am ]
Post subject:  Re: 68020 + 68881

My entire career was in computer hardware design. Software are mostly device drivers, diagnostics and debugger so I prefer to work with assembly language at low level of abstraction. This is why I love 680x0 so much and particularly happy with EASy68K tools.

Ironically in my retirement I want to move toward high level languages and OS--that was something I missed out and now trying to catch up with the rest of the world. Never used CP/M and seldom Linux in my career, I'm now interested in them. I might even be mad enough to try object-oriented programming!

I was successful porting CP/M68K to my two 68000 hardware platforms. Both platforms have no floppy disks, however--they have Compactflash instead. Sector translation is quite simple on CF using Logical Addressing. If you are interested in that, I'm happy to share my code with you. EASy68K was very helpful with the CP/M68K porting process.

I also want to port uCLinux to the 68000 platforms. One of the hardware platform has 16meg of RAM so I think it should be able to handle the larger memory needs of uCLinux. This will be a significant challenge to me as I'm unfamiliar with Linux.

Author:  hancock [ Mon May 07, 2018 7:19 pm ]
Post subject:  Re: 68020 + 68881

Hi Plasmo and all,

after some I could not prevent myself of digging out my 68k-boards and start over playing around.
Perhaps there should be a new thread on CP/M-68k?

As already stated I was giving up on the rightly reading from floppy-image files because I had not information in which drive they have been created.
I am successfully starting up CP/M in Easy68k, but then it is crashing on read errors in the floppy files.
Is there a solution to it?
Or how did you exactly get to the floppy contents?

Thanks and regards

Author:  Plasmo [ Tue May 08, 2018 3:00 am ]
Post subject:  Re: 68020 + 68881

There is already a CP/M68K topic. I posted a reply there:

Author:  legacy [ Sat May 26, 2018 8:17 pm ]
Post subject:  Re: 68020 + 68881

Thanks :D

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