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68060 board for the NeXT slab
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degs



Joined: 21 Sep 2006
Posts: 34
Location: Conway, NH

PostPosted: Sat Dec 28, 2013 2:04 pm    Post subject: 68060 board for the NeXT slab Reply with quote

I'm making a 68060 board as a replacement for the 68040. The schematics are finished, but there's a few software curiosities that I am trying to iron out.
( http://nextretro.blogspot.com/ is my work log, and the files are in svn: https://code.google.com/p/nextretro/) I have some ideas how to handle some of the software issues in hardware, but I would rather not.

The PTEST instruction does not exist on the 060, and it might not be used in the 040; however, I cannot seem to get one of the ROMs off the site to disassemble. Does anyone have this? If PTEST is used in the ROM, I believe that I have a fix for it.

The other question is if anyone has tried to make a custom interrupt. Some of the other potential issues can easily be handled by interrupts and a few traps. I have no idea if anyone has tried to do this in the NeXT kernel, but as far as assembly, it's straight forward.

Any information regarding PTEST or kernel hacking interrupts would be greatly appreciated.

--degs
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jroark



Joined: 17 Feb 2012
Posts: 75
Location: San Francisco, CA

PostPosted: Sat Dec 28, 2013 2:24 pm    Post subject: Reply with quote

very cool! Do you think the same upgrade would work on a 040 Cube?
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degs



Joined: 21 Sep 2006
Posts: 34
Location: Conway, NH

PostPosted: Sat Dec 28, 2013 7:13 pm    Post subject: Reply with quote

jroark wrote:
very cool! Do you think the same upgrade would work on a 040 Cube?


Well, I don't know. I've never seen an 040 cube. I need to make everything "fit" in the slab. If you can point me to an 040 cube motherboard picture and denote where the "missing pin" is on the 040 socket for orientation, I can see if I can get them both to fit.

I also haven't checked if there are 040 cute schematics in the archives to see if it has a muxed bus like the slab. I'll try to make it physically universal.
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andreas_g



Joined: 30 Jan 2009
Posts: 422
Location: Austria

PostPosted: Sun Dec 29, 2013 2:34 am    Post subject: Reply with quote

degs wrote:
The PTEST instruction does not exist on the 060, and it might not be used in the 040; however, I cannot seem to get one of the ROMs off the site to disassemble. Does anyone have this? If PTEST is used in the ROM, I believe that I have a fix for it.


I just tried to check this on Previous (Emulator). Obviously the ROM does not call PTEST, but the kernel of course does (emulating 68040 NeXTcube, ROM 2.5 v66, NeXTstep 3.3).
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jroark



Joined: 17 Feb 2012
Posts: 75
Location: San Francisco, CA

PostPosted: Mon Dec 30, 2013 1:05 pm    Post subject: Reply with quote

Are you sourcing new 68060s? I've got a couple NOS

MC68EC060RC60
MC68EC060RC66

but they don't have an FPU or paged MMU

and one or two MC68LC060RC66 (no FPU) soldered to Nortel boards

There seem to be a few XC68060RC50As on eBay for ~$80-$200, however 68060s seem to be pretty hard to find. Especially the 60-75mhz versions.
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degs



Joined: 21 Sep 2006
Posts: 34
Location: Conway, NH

PostPosted: Tue Dec 31, 2013 6:28 am    Post subject: Reply with quote

jroark wrote:
Are you sourcing new 68060s? I've got a couple NOS
MC68EC060RC60
MC68EC060RC66


I have two new 68060s at 50MHz and the impedance matched sockets for them. If I this works, I will make a run of boards. The 68060 will be the limiting factor in producing a number these boards; however, I am pretty sure that I can get some more. I'm just hoping to get *one* working prototype at this point.
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jroark



Joined: 17 Feb 2012
Posts: 75
Location: San Francisco, CA

PostPosted: Tue Dec 31, 2013 9:42 pm    Post subject: Reply with quote

Here is a 68060->68040 adapter

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degs



Joined: 21 Sep 2006
Posts: 34
Location: Conway, NH

PostPosted: Wed Jan 01, 2014 5:08 am    Post subject: Reply with quote

jroark wrote:
Here is a 68060->68040 adapter


The stock "adapters" will not work, I am sorry to say. The NeXT uses a multiplexed bus. Unless the adapters handle all of the glue logic required. I'll check it out.
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domiel



Joined: 20 Jul 2008
Posts: 37
Location: Sydney, AU

PostPosted: Sat Jan 04, 2014 5:28 am    Post subject: Reply with quote

Sounds like a fun project but perhaps you should consider using an FPGA instead?

A few people seem to have already gone down this path for other 68k based machines:

http://www.inertial.biz/index.php?title=VC68040

http://amigabillprojects.wikispaces.com/FP68060


http://propeller.wikispaces.com/pProp040
(not quite the same but interesting none the less)
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degs



Joined: 21 Sep 2006
Posts: 34
Location: Conway, NH

PostPosted: Fri Jan 10, 2014 10:37 am    Post subject: Reply with quote

domiel wrote:
Sounds like a fun project but perhaps you should consider using an FPGA instead?


This would be a perfectly fine approach, but I chose not to go down it due to time, and power. The 68040 is close to a nightmare due to compatibility and the MMU/FPU. Can it be done? Of course! Do I have the time to do it? No. I actually have a 68EC040 VHDL description somewhere from a previous project and it didn't have that much of a speed increase, and it did not have a MMU/FPU in it. Granted, it was an ancient 5V part. Also, if you want the cache, you will quickly run out of slice space and power.

If I currently had students that wanted a project, I would throw them at it, but I'm out of the uni currently. Perhaps in the future we'll see something that is a soft core. Actually, if I had a verified, complete description, I probably could get a grant for a run of them as one-offs on 130nm shuttle runs because I have the tools target the 130nm libraries. There are still some applications that use 68040s out there.

I wish that I was wealthy. It would cost 100k in masks and then about $1000 per wafer to make a cache heavy 68040 in a modern process. That'd be about 60 IC per wafer at least. There are some things to do with 100k that's sexier than getting a Ferrari.
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degs



Joined: 21 Sep 2006
Posts: 34
Location: Conway, NH

PostPosted: Tue Jan 21, 2014 2:42 pm    Post subject: A few changes, 68040 now too. Reply with quote

So, as with most of my projects, I get scope creep. It occurred to me that I can make the adapter board take a 68040 or a 68060, with just a few wiring changes. In that way, one can run a 68040 at 50Mhz without touching the the NeXT board and more people can use my work. (My current design takes the bus-clock and divides it by 2, and then you can multiply that up in 1/2 steps up to 6.) Also, this allows me to test the hardware in a better way since I will have to do some hot patches to the kernel for the 68060 (sorted this one out too I think).

It also occurred to me that I can put an external cache on this. I'm still working on the schematics, but the block diagram looks promising. The MUXed NeXT bus sort of ruins my groove here because the computer is designed in a way completely differently from how I would do it, but it was designed by really bright people so they obviously knew what they were doing.

On the notion of caching, does anyone know where there is a NeXTStep memory map floating around? I have been told that the maximum RAM in the NeXT is 128megs, but does anyone know where that would sit in the address space? Also, do all NeXTs share the same address space, or is it different for different systems?
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andreas_g



Joined: 30 Jan 2009
Posts: 422
Location: Austria

PostPosted: Tue Jan 21, 2014 11:42 pm    Post subject: Reply with quote

degs wrote:
On the notion of caching, does anyone know where there is a NeXTStep memory map floating around? I have been told that the maximum RAM in the NeXT is 128megs, but does anyone know where that would sit in the address space? Also, do all NeXTs share the same address space, or is it different for different systems?


For the emulator project i also needed the memory map for RAM. You can take a look here (the relevant post is towards the end of the page):
http://www.nextcomputers.org/forums/viewtopic.php?t=2642&postdays=0&postorder=asc&start=165

It is different for different systems. I hope the above link helps.
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degs



Joined: 21 Sep 2006
Posts: 34
Location: Conway, NH

PostPosted: Mon Jul 07, 2014 7:20 am    Post subject: equivalent cc version for NeXTStep? Reply with quote

Hello everyone. I'm still plugging away at this project, but I ended up getting swamped in the world of semiconductors.

What's an equivalent gcc version for whatever cc is used on NeXTStep 3.3? I have what I believe will be my final board version and I have my kernel rewrite code mostly working, but I want it to run on the NeXT as well.
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sdinet



Joined: 25 Jun 2008
Posts: 184

PostPosted: Wed Jul 09, 2014 7:06 am    Post subject: Reply with quote

I have a NeXTstation 68040 running at 50mhz (overclocked), let me know if you'd like info on how it was done, I am happy to help.
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gtnicol



Joined: 27 Dec 2005
Posts: 525
Location: Rhode Island, USA

PostPosted: Wed Jul 09, 2014 10:47 am    Post subject: Reply with quote

I don't know if pyro/nitro boards might be of any help, but the offer is there...
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