One thing my emulator is going to need to work, is an original operating system. If we were talking about Windows, DOS or even CP/M, then it wouldn’t be a problem. But were talking about a propriety 15+ year old operating system from a company that no longer exists and used on a single range of computers which are all but extinct.
So it’s lucky that when the company I worked for after working for Nixdorf went out of business, I spent my final minutes there on-site (we really didn’t get much notice to vacate the building),backing up my 8870 development system, and I kept the tape.
The problem is that these 9 track half-inch tapes don’t age well if they are stored in less than ideal conditions. The tape is actually made from a plastic material with a magnetic coating bonded to it’s surface using a hygroscopic glue (absorbs moisture from the atmosphere). What all this means is that if you start running an old tape through a tape drive there’s a good chance that the tape is going to fall apart and be ruined.
Lucky for me during one of my scouring the Internet for information sorties, I found VAXMAN. Go check out his site. We started Emailing as you do, and I happened to mention my problem with the tape, though I was more worried that I didn’t have an actual tape drive to read it on. VAXMAN offered to recondition the tape (by placing it a nice warm oven for a while which apparently doesn’t damage the magnetic coating or the data), and the reading it’s contents onto one of his VAX machines. He could then spool the data into a tape image that I could then read.
I got an Email from VAXMAN the other day saying the tape had arrived, but it may not be good news. Whilst the tape is physically intact there appeared to be a lot of parity errors when the tape was read, but hopefully, theres a good reason for this.
So it’s lucky that when the company I worked for after working for Nixdorf went out of business, I spent my final minutes there on-site (we really didn’t get much notice to vacate the building),backing up my 8870 development system, and I kept the tape.
The problem is that these 9 track half-inch tapes don’t age well if they are stored in less than ideal conditions. The tape is actually made from a plastic material with a magnetic coating bonded to it’s surface using a hygroscopic glue (absorbs moisture from the atmosphere). What all this means is that if you start running an old tape through a tape drive there’s a good chance that the tape is going to fall apart and be ruined.
Lucky for me during one of my scouring the Internet for information sorties, I found VAXMAN. Go check out his site. We started Emailing as you do, and I happened to mention my problem with the tape, though I was more worried that I didn’t have an actual tape drive to read it on. VAXMAN offered to recondition the tape (by placing it a nice warm oven for a while which apparently doesn’t damage the magnetic coating or the data), and the reading it’s contents onto one of his VAX machines. He could then spool the data into a tape image that I could then read.
I got an Email from VAXMAN the other day saying the tape had arrived, but it may not be good news. Whilst the tape is physically intact there appeared to be a lot of parity errors when the tape was read, but hopefully, theres a good reason for this.
Cipher 880 1/2' 9 track tape unit.
The 8870/M45 I used to create the tape had a Cipher 880 tape unit installed. These can read/write at either 1600 or 3200 bpi. Unfortunatly the tape unit that VAXMAN uses works at 6250 or 1600bpi. The Cipher default is 3200bpi so this could explain why it can’t be read. It’s not all bad news as he does have other tape drives that will do 3200bpi, but it’s not a simple job for him to reconfigure all the hardware.
Another problem may be the “mode” that was used to write the tape. The 8870 supports two modes of operation; streaming and start-stop mode.
Another problem may be the “mode” that was used to write the tape. The 8870 supports two modes of operation; streaming and start-stop mode.
Streaming mode is used for fast system backups. The problem is that tapes written in this mode weren’t designed to be read on other manufacturers systems. I’m not saying hat you can’t read them, it’s just that usually, if we were writing tapes for other manufacturers computers, they had to be written in start-stop mode. My tape is a standard system backup tape, so was written in streaming mode, so it’s possible that the tape is perfectly fine, it’s just that I need an 8870 to read it on. It could also be that the tape is completely knackered. I’ll wait and see what VAXMAN suggests as to what to try next since he's got the hardware... and all the work to do.
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