Talking to the direct interface should be much easier interface-wise. The added difficulty is that you are now responsible for formatting. The interface is well documented (look for 5952-5441_HP_7970E_Interface_Guide_May71.pdf), at least for the E.
Marc From: Jack Harper [mailto:har...@secureoutcomes.net] Sent: Thursday, October 05, 2017 4:47 PM To: Curious Marc; cctalk@classiccmp.org Subject: Re: (Classic Computers) HP 7970 1/2" 9-Track Reel-to-Reel Tape Drive Marc - I certainly do know you from your great YouTube videos. Because of the video on the Overland Data drive, I bought one of those that popped up on eBay, but it will not find load point. The output voltages from the BOT sensor look, I think, good or at least reasonable: +0.3VDC for the DARK condition and +3.0VDC for the LIGHT condition. The drive failed all of the power-on diagnostics when I first got it, but I discovered how to re-initialize NOVRAM to "factory settings" by weird button pushes - Did that and all was well. However, the drive will not, now, find the load point and so I am stuck. That was interesting to me as you had the exact same problem with the 7970 on your YouTube video - burned out light bulb. I believe the problem in the Overland to be something other than the BOT sensor. I considered a SCSI tape drive, but really I want the classic open reels with the classic fast/stop action. Reliving, of course, my childhood when I grew up living inside a UNIVAC 1108 - assembly and all that - and all those drives start/stopping :) I consider this a long term project if I tackle it - clearly not something that I can dash together over a weekend. Do you think that parity issue on commands is only for the HP-IB controller and not if I end up talking direct to the internal controller of the 7970 tape drive?? Any idea on that? Regards to the List, Jack At 12:22 AM 10/4/2017, Curious Marc wrote: Jack, You can drive an HP-IB equipped HP7970E with an old PC that has an HP-IB card using Ansgar Kueckes HPDIR. I debugged it together with Ansgar. The rub is that it only worked well with an ISA HP-IB card running under Win98. The PCI HP-IB card running under XP uses a driver that causes timing errors and it skipped some records, and I don't think Ansgar ever bothered to fix it - we were happy enough to have made one solution work... The commands used to read and write from the tape are complex and tricky, and you have to get your timing right as there is hardly a buffer in the interface (128 bytes). And there is this weird parity thing, where parity has to be generated for commands on the HPIB bus, but not for data, or something of that ilk. If not the tape just hangs the bus. There are several GPIB emulators based on Arduino that should enable you to build an interface. You know me, I made several videos documenting the work on the 7970E tape: https://youtu.be/eCBxNhEzIfc?t=7m6s (tape interfaced with a PC running Ansgar HPDIR) https://youtu.be/5J8IbpJoeqk (shows how I sniffed the HP-IB bus to figure out how the commands worked - or didn't, also has a demo of sending a rewind command in the raw via a paddled-in program) https://youtu.be/YS9dGYUbNd0 (showing a demo with the tape attached to an HP-85, using an FPGA based gizmo to take care of the on-the-fly parity generation) https://youtu.be/rAsLwcq4RNU (fixing a loading fault on the tape drive) Although I love the HP 7970E dearly and want to encourage you to try your luck at it, that was a lot of work to get it to work on something it wasn't meant for. You'd have a much easier time bringing up a SCSI based tape. Marc Subject: (Classic Computers) HP 7970 1/2" 9-Track Reel-to-Reel Tape Drive Question: Anyone have experience talking to a 7970 tape drive from something other than an HP computer - something that does not have HP-IB??? How is that usually done?? Jack Harper Evergreen, Colorado ---------------------------------------------------------------------------- ------ Jack Harper, President Secure Outcomes Inc 2942 Evergreen Parkway, Suite 300 Evergreen, Colorado 80439 USA 303.670.8375 303.670.3750 (fax) http://www.secureoutcomes.net <http://www.secureoutcomes.net/> for Product Info.
