CXP board

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Scott Larson
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Joined: Fri Nov 14, 2008 8:32 pm

CXP board

Post by Scott Larson » Mon Nov 10, 2014 6:59 pm

I took a look at the pile of OSI stuff I had in the basement. Big surprise. The CPU board plugged into the bed of nails known as the OSI 48 pin bus was not an OSI board at all. It was a "CXP". A Peek 65 article shows that this was an OSI CPU clone with a nice 65816, 64K of RAM on the board, and a floppy controller that could even use standard floppy drives.

I have absolutely no memory of using this board. It appears I had it plugged into dual 8 inch drives (which I probably got cheap) but there was no video board so I don't know what interface I was using although I may have more OSI boards laying around. There is an EPROM in it so I may have copied the OSI monitor ROM to get it booted. I had soldered some stuff into it so I know I was using it for something.

I probably got this board shortly before I got a real software job working with giant Unix computers, so I quickly lost interest in it.

dave
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Re: CXP board

Post by dave » Tue Nov 11, 2014 12:50 am

Scott, that's an amazing find! Would you be willing to take some high-res pictures of the board? If you are willing, I'd love to include the board in the hardware section of the repository.

It seemed as if the software for the board was at a very rudimentary stage. I'm curious if any operating systems, such as a modified OS65D, were brought up for it. If you do find any software efforts, it would be quite interesting.

Dave

Scott Larson
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Joined: Fri Nov 14, 2008 8:32 pm

Re: CXP board

Post by Scott Larson » Tue Nov 11, 2014 4:53 pm

Sure, I'll take photos of both sides on Thursday. It looks just like it was described in the Peek 65 article: a CPU section, a disk section, and a huge area of long complicated traces so it would plug into the 48 pin bus.

Like I say, I can't even remember purchasing the board much less doing anything with it. I still have no clue where my C1P is which is sad because that thing taught me how computers worked and that's how I got a career in software.

Scott Larson
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Joined: Fri Nov 14, 2008 8:32 pm

Re: CXP board

Post by Scott Larson » Thu Nov 13, 2014 4:00 am

Here they are:

http://www.wballphotos.com/CxP_Front.jpg
http://www.wballphotos.com/CxP_Back.jpg

I have no idea what various mods I did to it. I'm guessing the stuff around the EPROM was to fit a smaller chip into a socket that probably wanted a larger more expensive chip. Even more odd, two of the pins on one of the 6551 ACIA chips were out of the socket.

I believe the missing chip in the disk section was probably a standard disk controller chip which I didn't need since I was using OSI-compatible drives.

MK14HAK
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Location: New Zealand

Re: CXP board

Post by MK14HAK » Sat Nov 22, 2014 7:03 pm

Scott, what yr,vol was the Peek article describing this? Do you have any OSI software and working hardware?
Scott Larson wrote:I have a stack of OSI stuff in my basement. I don't know if my C1P is still in there but the C8P (or some variation of it) with gigantic 8" floppy drives is definitely there. I'm scared to plug it in since I see a wax paper-coated transformer whenever I walk past it and it looks like fire to me.


Is the C8 power supply the same type as the C4 one I see here: http://www.6502.org/users/sjgray/comput ... 4P2006.jpg or are you referring to the floppy PSU. Are they the same ? (may like this: http://www.technology.niagarac.on.ca/pe ... r2POEM.jpg ???)

Can the power supplies be disconnected from the backplane easily and fired ! up on their own ?
Mike
600RevB:16K,2MHz,64x32,470,CEGMON
SuperKit:502,540B,542B,CEGMON, 8" and 5" FDDs
Cards:PE IO,6522 D-A-D, AY3-8910,ProgramGraphics,Color,UK101
WIP:Archive/Restore Util,HexDOS,FDD Emulator

Scott Larson
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Joined: Fri Nov 14, 2008 8:32 pm

Re: CXP board

Post by Scott Larson » Mon Nov 24, 2014 8:31 pm

The CxP article was in the January/February 1987 issue of Peek 65.

I appear to have the C8P chassis and there are two power supplies like I see in the images so I guess these were separate floppy and backplane power supplies. For some reason my dual 8 inch drives are in yet another cabinet (not OSI) which I haven't opened yet. I probably got a good deal for them since what sane person would still be using 8 inch drives in 1987?

No, I have no working OSI hardware and I don't have any interest in hardware any more.

pchidley
Posts: 1
Joined: Mon Dec 08, 2014 5:17 pm

Re: CXP board

Post by pchidley » Mon Dec 08, 2014 5:27 pm

WOW, I had totally forgotten about that board.

Yes I designed the CXP a VERY long time ago.

Here's a couple of fun facts (if anyone still cares).
The board as pictured did indeed fit the OSI48 microbus with its corrosion prone tin plated connectors and pins.
However you could cut the two halves into standard Eurocards. One of my homebrew systems used DIN connectors and standard Eurocards.

The schematic existed only on paper. (No CAD in those days) The PCB was laid out ON AN OSI COMPUTER. Yup, I wrote my own crude PCB layout program that then printed the artwork on a dot matrix printer at 2x scale. The printout was then photographed (professionally) with a yellow filter to increase contrast and reduced to 1:1 positives on film. Those were used to etch the boards.

Memory lane indeed. But I need to get back to work.

Regards,

Paul Chidley

Steve Gray
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Re: CXP board

Post by Steve Gray » Mon Dec 08, 2014 5:40 pm

Hi Paul,

Good to see you here! The board looks really nice, thanks for the info. I attended a few TOSIE meetings back in the day and we probably met, and you may have even repaired my C4P cpu board. I have one of your TOSIE hacker boards that I never fully completed. But I was able to use it to mount a Mittendorf high-res board and get that working in my system. Did you work on any other OSI boards?

Steve
C4P+D&N floppy not working, 2x C4P not working, C1P not working, Superboard not working.
505 board, 610 board, Mittendorf board, TOSIE hacker board need testing, PicoDOS disk untested

dave
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Re: CXP board

Post by dave » Wed Dec 10, 2014 4:35 pm

Hi Paul,

Thanks so much for stopping by and posting! If you ever have the time, it would be great to hear more about your OSI experiences. That's the first I ever heard if anyone doing PCB layout on an OSI. I'd be extremely interested to learn more about what you did.

Dave

Scott Larson
Posts: 17
Joined: Fri Nov 14, 2008 8:32 pm

Re: CXP board

Post by Scott Larson » Tue Mar 03, 2015 12:42 am

pchidley wrote:WOW, I had totally forgotten about that board.

Yes I designed the CXP a VERY long time ago.
Good to hear I'm not the only one who forgot about the CxP. I can't for the life of me remember what I was using it for. I don't remember owning any OSI video boards so apparently I was using my C1P as a terminal to it. That would explain the hacks to the serial port section. I don't remember doing any 65816-specific code which

I'm pretty sure I got this board right when I started working on bigger and more exciting machines.

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