Aquired PDP 11/23

allison ajp166 at
Sun Mar 12 18:30:38 CDT 2017

On 03/12/2017 04:56 PM, Systems Glitch via cctech wrote:
>> Are dectape II tapes expensive?
> TU58? They're hard to come by, but the good news is you can *emulate* them with a PC and a serial port (or USB adapter). That's how I run XXDP on most of my systems, and pretty much all of the systems I check out for people. You've got a DLV11-J in there so you've already got SLU0 in place (or can strap it up for it). AK6DN has a bunch of useful TU58 images premade, with listings of what XXDP utilities are on them.
What makes them hard to come by is that they must be preformatted for
the TU58, as far as I know
only DEC had hardware to do that.  The Drive as it stands cannot do that,

It is not capable of higher storage capacity as a result (hardware
limit, programming and no formatting).
> It's also possible to boot other OSes on TU58, like RT-11. There's even a patched RT-11 driver to fudge the capacity on TU58s so you can use the emulator(s) to store a much larger volume of data. Helps to set SLU0 for a higher speed than 9600 if you plan on doing that :)
I run RT-11XM using TU58 a real one.  Boot times to load the RT-11XM:
driver and copy the tape and boot
to XM: virtual disk that takes about 5 minutes.  That's with the files
optimally placed on the tape
(in order of need) to limit the number of rewinds.

The VAX750 used TU58 to load microcode and diagnostics. Any os that can
fit on the 256K per tape
times two tapes would likely be bootable if it can do the serial
protocal used for the booter and the OS.

A PC emulation (or Rpi) can do this a bit faster (just over a minute for
a boot can copy to VM:) but you are
limited to the max baud rate (38K) of the serial port use by the DD

There was at least one company that used a floppy drive (360K 5.25 or
720K for two sided) with a TU58 emulation
that was somewhat faster than tape due to faster seeks to a block.


> Thanks,
> Jonathan

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