Jonathan, I like your thinking! Actually, I've already done something that works well for a lot of what you mention. Please watch this YouTube video I created for my Universal QIC tape reader. https://youtu.be/BfKUJmPSam0 I've read a number of different head/track configurations with this, by finding the tracks of the 9 that overlap with the 4, and choosing the correct direction on my manual switch control. Very much a trial-and-error process to get there. This has worked very well for me on the handful of odd-format tapes that I have read so far. One of those formats is a really weird 4-track format, and here's my page on the breakdown of that, and how I read that 4-track with my 9-track reader. http://microtechm1.blogspot.com/2015/09/kennedy-6450-tape-drive-data-format.... I hope these resources inspire you for a solution to save this data! Also, about the drive-wheel turning to goo, all of the drive wheels in my drives did this, and I've had them all replaced by Terry's Rubber Wheels ( http://terrysrubberwheels.com ), so using a good rebuilt wheel is very important in my opinion. Many here have also rebuilt their own drive wheels. I do have experience baking these tapes now. (Not nearly as much as others here, though). I hope to create a YouTube video for that in the next few days, because that's one of the things I would have found extremely helpful when starting to learn about QIC tape restoration. My success with that was me putting into practice advice I've received from many who post here regularly. But, until I create that YouTube video, please see these posts, which give a lot of good instruction on the matter. The advice in these posts is exactly what I followed, which gave me success: http://bit.ly/2176PiI The internal tape belt/band is an issue as well, which probably should be replaced after the old one was removed for tape baking. I have created 2 videos on that as well, and linked the discussions of those more experienced than I on that topic, which inspired my processes, below each video. 1) https://youtu.be/70PDHfdbsvY 2) https://youtu.be/Ku1lKY-2mGs I hope this helps! -AJ On Thu, Nov 19, 2015 at 10:46 PM, Jonathan Gevaryahu via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On 11/16/2015 4:16 PM, Evan Koblentz via vcf-midatlantic wrote:
I hope that it is ok that I signed on to your list. I am from germany
Welcome!
and I'm looking for information about the Zilog System 8000. I know that
you owned at least one in the past. I don't know if you still have it, but I hope so :)
We have it, but we haven't done much with it. Perhaps at our next repair event. We have workshops here every few months.
Note I've been told QIC tapes of this age most likely (95% chance) have to be "baked" to prevent them from turning to mush against the drive heads. (I'm not 100% sure how the baking process is gone about, but I believe it requires disassembling the cartridge and removing the tape spool, and wrapping the tape around a special metal spindle, then heating it to a certain temperature for a few hours. I could be way off here.)
Also, to recover the data from these tapes, given the drive capstans (and cartridge capstans?) always seem to turn to goo and we're not sure if the z80-based interface card works or not... Would it make more sense to get any old QIC drive that is sufficiently old enough to be hackable but has intact rollers, and (after baking the tapes) use an FPGA development board and some breadboarded analog amplifier magic to directly control the QIC motor and tap the QIC drive heads for the 4 tracks, and either record them as analog waveforms at a high samplerate, or log time-deltas (in 50mhz clocks) between flux transitions? Then decode the resulting flux stream entirely in software. 50mhz may be extreme overkill, its possible digital sampling at 192khz or twice that may be fast enough, I don't really know...
I could have sworn someone on this list, or in another similar list (classiccmp?) had already worked out a setup for decoding tapes just like this...
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
-- Thanks, -AJ http://MicrotechM1.blogspot.com