xt/layers

[3673,ATTT]

In article <1989Oct30.063026.8242 at banzai.PCC.COM> john at banzai.PCC.COM (John Canning) writes:
>In article <2502 at flatline.UUCP> jet at flatline.UUCP (j. eric townsend) writes:

>>Just what is it? [layers]
>>wtinit says I must run it from a "DMD terminal"...

>xt/layers runs with the AT&T 615 and 630 terminals. 

The entire family of DMD terminals (all by AT&T) includes the 
old Teletype BLIT, the 5620, the 615, 620, and 630.  These terminals
allow you to download a basic window manager for the terminal for
the host computer.  programs (editors, previewers, games) can be
downloaded onto the terminal to run.  on my 630 at work i have a
troff previewer and a bitmap editor currently loaded.

the old 5620 terminal uses an mc68000 processor for management.
i believe that the 630 is the same.

>It allows you to
>run several processes from one terminal (aka the suspend function key
>on the main console).

the method used is similar to that of shell layers (shl), in that a
number of "virtual devices" (/dev/xt### in this case) are created
and i/o to the terminal is done through these)

>I found xt/layers to be a bit on the slow side.  Although several of
>our customers have 615 terminals, none of them are using xt/layers.

The  "slowness"  can also be attributed to the fact that all this
communication is still run over you standard serial line.  we
are not dealing with that great a bandwidth.


>John Canning	
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