The OSI C4P Page

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Steve Gray
Posts: 281
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada
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The OSI C4P Page

Post by Steve Gray » Mon Oct 06, 2008 2:05 pm

Hi,

My name is Steve and the OSI C4P was my fist computer, purchased in 1981. I live in Markham, Ontario which is just north of Toronto, Canada.

I have a web page dedicated to the C4P here and related info. Check it out if you can.

My C4P is curently working and includes a D&N floppy controller and drive. I have the TOSIE hacker board and mittendorf hi-res graphics board which were working last time I checked but are not currently installed. I also have a Superboard which is currently not functional but I hope to restore if time permits.

Glad to see this forum back up again as there seem to be fewer and few of us remaining and lots of old info and knowledge will be lost of we don't make an effort to preserve it.

Steve
C4P working, C1P working. 600D Replica working, C4P+D&N floppy not working. 505 board, 610 board, Mittendorf board, TOSIE hacker board need testing, PicoDOS disk untested.

dave
Site Admin
Posts: 560
Joined: Tue Sep 09, 2008 5:24 am

Re: The OSI C4P Page

Post by dave » Wed Oct 08, 2008 8:18 pm

Thanks for sharing your site. I've linked to it on the main page. I am very interested in the Mittendorf board, as I had hacked a high-res mod for the 540 board, basically a 16K RAM board which multiplexed the 540 board video timing divider chain outputs with the address lines, and the data lines connected to a shift register, which was conditionally combined with the 540 shift register output. This was messy, basically hung off the 540 board with wire-wrap wire connects. Unfortunately, that hack is long lost. That was before I found out about the Mittendorf board, otherwise I might have just splurged. I'd love photos, schematics, and written docs, if you have them.

I'd also love any info you have on the D&N board and the TOSIE board.

Dave

Steve Gray
Posts: 281
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada
Contact:

Re: The OSI C4P Page

Post by Steve Gray » Sat Oct 11, 2008 3:50 am

dave wrote:Thanks for sharing your site. I've linked to it on the main page. I am very interested in the Mittendorf board, as I had hacked a high-res mod for the 540 board, basically a 16K RAM board which multiplexed the 540 board video timing divider chain outputs with the address lines, and the data lines connected to a shift register, which was conditionally combined with the 540 shift register output. This was messy, basically hung off the 540 board with wire-wrap wire connects. Unfortunately, that hack is long lost. That was before I found out about the Mittendorf board, otherwise I might have just splurged. I'd love photos, schematics, and written docs, if you have them.

I'd also love any info you have on the D&N board and the TOSIE board.

Dave
Thanks for the link.

The OSI machines were very hackable. Sounds like you really got into it. I was only at the level of being able to solder and follow instructions when it came to hardware. I couldn't design anything myself. Programming on the other hand came naturally ;-)

I've dug out my documentation binders and can't find anything at all about the D&N board or the Mittendorf board... It's funny, the D&N board has dip switches so there must have been some documentation. I'll keep looking; perhaps it's in another box somewhere... The TOSIE board has some documentation (board layout, fix/mod instructions etc) but no schematics. There are some pics on my site but they are scaled for the web. I'll try to take some new photos for you.

Steve
C4P working, C1P working. 600D Replica working, C4P+D&N floppy not working. 505 board, 610 board, Mittendorf board, TOSIE hacker board need testing, PicoDOS disk untested.

Steve Gray
Posts: 281
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada
Contact:

Re: The OSI C4P Page

Post by Steve Gray » Fri Oct 09, 2009 2:33 pm

Hi All,

A note to let everyone know that my OSI C4P Web Page has moved. It is now located here:
http://www.6502.org/users/sjgray/comput ... index.html

I finally have more storage space and hope to expand the info/pictures/etc in the near future. If you have feedback or suggestions please email me directly.

Steve
C4P working, C1P working. 600D Replica working, C4P+D&N floppy not working. 505 board, 610 board, Mittendorf board, TOSIE hacker board need testing, PicoDOS disk untested.

Jeff
Posts: 330
Joined: Fri Mar 07, 2014 4:44 am
Location: British Columbia, Canada

Re: The OSI C4P Page

Post by Jeff » Sat Mar 22, 2014 5:21 pm

Hi All,
I just purchased a Challenger 4PMF from Ebay and am excited to get it working. My first computer was a C1P way back in 1979. Unfortunately somebody cleaned out the basement and it must have got tossed. I recently purchased a working Superboard so I could re-live my early days of programming. That little C1P launched my programming career and 35 years later I am still love crafting code each day.

My C4PMF *was* working before it was shipped, but alas it did not survive the shipping. I have an old tektronix scope and a logic probe on order and they are due to arrive next week. I am hoping there is someone here on this forum that might be able to get this baby back to good health.

I have opened my unit and re-seated all the chips; When booting, I get a screen full of random characters but pressing shift lock-break does nothing. Interesting to note is that my system includes an OSI 541 board which I have not been able to find ANY information on. There is a ton of 2114 RAM chips and what looks like a character generator ROM on it. My system consists of the 505, 527, 540 and 541 boards.

I live near Vancouver in BC, Canada.

Cheers!
Jeff
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Steve Gray
Posts: 281
Joined: Mon Oct 06, 2008 1:54 pm
Location: Markham, Ontario, Canada
Contact:

Re: The OSI C4P Page

Post by Steve Gray » Sat Mar 22, 2014 7:03 pm

Welcome! Good to see you made it here. I'm sure there are people here who can lend a hand. Perhaps you can start a new thread and describe the problem(s) and what you have tried to fix them.

Steve
C4P working, C1P working. 600D Replica working, C4P+D&N floppy not working. 505 board, 610 board, Mittendorf board, TOSIE hacker board need testing, PicoDOS disk untested.

dave
Site Admin
Posts: 560
Joined: Tue Sep 09, 2008 5:24 am

Re: The OSI C4P Page

Post by dave » Sun Mar 23, 2014 4:25 pm

Hi Jeff, and welcome to the forum!

I think you will find several of us are happy to help you out here. As Steve suggested, you may want to open a new thread to discuss the repairs. Good call on ordering the scope and logic probe--you won't regret it. A digital multimeter could be of value as well.

If the computer was working before it shipped, then it may be something simple and mechanical. In fact, that's a good bet. First, try the easy things. The new C4 machines have a 3 second timer on the reset button. Did you try holding down BREAK for 3 seconds?

Next, check to make sure the reset signal is getting to the CPU. You may want to take a look at the two-wire cable between the cable and the 505 board to make sure it's intact and also that it's not shorted (I've seen blobby soldering jobs on those connectors that can short with a little force applied) With luck, perhaps that's all. To be sure, use the DMM to check for a short on those pins (unlikely), and then try shorting them out when you get the garbage character screen. Philip (Nama) recently had a problem with the reset circuit on his C4, so he is the resident expert :-)

Then, when you have the logic probe, try looking at the reset signal on pin 40 of the CPU. It should be high, and go low with reset. If this is happening, then try probing some of the other pins of the 6502. Get a copy of the datasheet (http://www.classiccmp.org/cini/pdf/Comm ... _c650x.pdf), and print it out, then check for activity on address and data pins (pulsing with a logic probe, periodic repetitive transitions betwen 0V and 5V on a scope).

That should be a good start.

Let us know how it goes!

Dave

Jeff
Posts: 330
Joined: Fri Mar 07, 2014 4:44 am
Location: British Columbia, Canada

Re: The OSI C4P Page

Post by Jeff » Mon Mar 24, 2014 3:55 pm

Thanks for the tips! I do have a DMM :-) I will start a new thread.

Cheers

/Jeff
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