Using Mass Storage Devices on Simh PDP-11 #PDP11 #VintageComputing

Big Dan the Blogging Man wanted to know how to transfer ASCII data in/out of the PDP-11 and any type of file between simulated PDP-11s. So they learned to use several simh mass storage devices on the PDP-11 emulator.

I definitely want to be able to get ASCII data into and out of the system. Way back when I was messing with the DEC-10 emulation I was doing this using a card punch and reader. Looking at the PDP-11 emulation there is no card punch and someone said the reader has an issue as well (I’ve forgotten what though).

This leaves the paper tape punch/reader. Which works just as well.

I don’t think I’ll have any need to transfer binary data (e.g. programs) INTO a PDP-11, BUT I might want to copy binary from one PDP-11 to another. This would be done using the floppy drive.

The simh controller for RX01 drives is call RX. The RT-11 devices are DX[n]: .

It appears DECTapes have less storage capacity than an RX02 floppy so there probably isn’t much point messing with the DECTape controller except as an experiment.

After using it a bit I realized that DECTapes work very much like floppies except they are much slower (in real-life, not the simulation). The 9 track tape drives I used in the days of the HP3000 didn’t have a directory nor could they be updated. The only ‘update’ possible was to append new data to the end.

Read more in the post here.

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