Restoring C8PDF

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lowrybt1
Posts: 212
Joined: Sun Mar 08, 2015 3:42 pm
Location: New York State

Restoring C8PDF

Post by lowrybt1 »

I’ve had success getting a C8PDF back to life. Involved replacing a bunch of bad 2114’s and modifying traces to allow use of 5.25 instead of 8 diskettes (I don’t have an 8” drive). I’m now am able to boot into 65D V3.3. I have three\four immediate questions:

1. I don’t have a disk 5 with the basic copier utility. Is there a single-disk copier utility embedded in the OS that I can call from the kernel?

2. I’m getting occasional flaky action from the keyboard. Of course some key bounce but the issue I’m seeing more of is random, inconsistent generation of characters with a key press. Also, occasionally it seems that the keyboard temporarily freezes but comes back to life without the need for a reboot. I’m guessing this might indicate noise over signal somewhere. Any thoughts on places to start with diagnosis of this? And any reason I should not use an electronic contact-cleaner to clean up the keyboard contacts?

3. Sometimes the machine will not permit disk boot until I first warm restart, enter the monitor, then warm restart and press D. Why??

Thanks for any guidance
C8PDF w. 48K, 2x 520 24K RAM boards and Glitchworks 64K board
OSI 567 Telephony board
Spare 8" drives
Klyball D-13
w4jbm
Posts: 23
Joined: Sun Jun 18, 2017 1:41 pm

Re: Restoring C8PDF

Post by w4jbm »

The only copy utility is the one written in BASIC. (I think there is an old Track 0 copy utility that was sometimes included, but even if so it wouldn't be much help.)

You can manually copy by reading a track into a buffer, swapping disks, and then writing the track from the buffer.

The BASIC program that did this was pretty simple. You do need to run CHANGE before you write your own program to set up buffer space in front of the BASIC program space. There were different versions of modified copy programs that floated around. If you set up two buffers with CHANGE, you can copy two tracks at a time and cut the number of disk swaps in half.

I spent a while working for a dealer as a repair tech during college, so I can tell you how I would have approached the others back then.

Does #3 only happen when you first start up or does it happen after that machine has run a while? Actually a lot of times with symptoms like #2 and #3, we would reseat all the socketed chips, the connectors, and the cards. A lot of flaky behavior was fixed that way. It wasn't very technical, but it worked.

The other thing I would tend to suspect is a chip that is beginning to have issues. For that, I would probably have used freeze spray. It may work fine once it has been on for a few seconds and warmed up.

It was just a rule of thumb, but if things didn't work at first but started working, we would use the freeze spray. If things worked but then stopped, we tended to do the reseating first. But I also took the ten minutes or so to reseat everything on virtually every machine I worked on.

On oscilloscope or even just some LEDs tacked into place could help you determine if the keyboard scan is running as regularly as it should. If the scan is flaky it is upstream of the keyboard and if it looks good when you have the issue the problem is probably downstream of the keyboard.

Messing with keyboard contacts was a big no-no back then, but that was three decades ago so it might be a necessary evil at this point. I don't have much to offer on that.

I always wanted a C8P. The owner was remodeling the store I worked at and a carpenter that was helping traded up an upgrade of his C2-8P for some of the work. New drives (the old white ones with external flanges were pretty much all dying by 1982 and they have moved to the black ones), a 510 board, a terminal, and the ability to run either OS65D on the video card & keyboard or OS65U on the terminal. There were a few hardware and software patches needed. (As I recall, a lot more than expected.) But I really wanted something similar at the time.

Thanks,
Jim
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