DEC VT20 boot device

Bob Smith bobsmithofd at gmail.com
Sat Aug 10 17:03:05 CDT 2019


The VT20 design team was, iirc, John Kirk for the video, and me for
the Unibus interface in the first version. The one with the slick
one shown here,
http://bitsavers.org/pdf/dec/terminal/vt20/vt20_2.jpg
The /05 based package was after my time, I don't remember much about
how it was deployed.
The boot device called using the boot strap board was variable, and I
don't recall anything beyond an RK05
based system (booting the RK) for the versions in the lab on 1-2 in the mill.

It was for the Typeset 11 team, and then the TypeSet.DecSet team/Product line.
bob

On Sat, Aug 10, 2019 at 2:56 PM Paul Birkel via cctech
<cctech at classiccmp.org> wrote:
>
> The DEC VT20 terminal apparently included a PDP-11/05 with a direct mapped
> character display and was intended for text editing and typesetting.  It
> seems to have been followed by the VT21, and then VT71/VT72, all three based
> on an LSI-11 (KD11-F).  There's a real lack of documentation about these
> online, although the VT72 does have a print set.
>
>
>
> Apparently the VT20 used the M792-YK as its bootstrap; the Field Guide is
> silent regarding the boot device and M792 documentation stops earlier in the
> series of variants.
>
>
>
> According to the VT72 print set, it used the MRV11-VC (M9942-YC; described
> in the Field Guide as a "bootstrap/diagnostic module") for its bootstrap but
> is also silent regarding the boot device.  In interestingly, the Field Guide
> also describes a MRV11-AA (M7942-TB) as a "M7942 with VT52 emulator, VT71
> bootstrap".
>
>
>
> For async. communications the VT20 used a DL11-B (M7800 (EIA)). the VT72 a
> DLV11-F (M8028).
>
>
>
> Looking in a DEC "Options and Modules" listing I see VT20 bundles including
> Typeset-11 and DECset-11, and it appears that the VT20 could be configured
> with two displays & serial lines in a single 11/05.
>
>
>
> So . is the boot device in these systems the remote host via the serial
> line?  What protocol would that have been?  Something native to Typeset-11
> and DECset-11?
>
>
>
> paul
>


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