Just add the vt100 entry from 4.1 you might be fine.  FYI:To there credit, when the VT-100 was being developed the spec was a moving target and Tom Kent and his brothers and sisters in the terminal group did an amazing job -- but ....  VT-100 are not completely ANSI (DEC released before the spec was ratified smd it lacks some features that are really needed).   It uses scrolling regions to do some of the painting/update -- Mary Ann undoubtedly has nightmares.  

The termcap code in 2BSD is very early and may not be smart enough to do some of the tricks that VT-100 demanded, so it might be wise to swipe the 4.1/4.2 version and see if you can substitute.   Also remember Sys V used terminfo [again Maryann can explain having fought that war].   Termcap was included in later versions by demand.   

On Wed, Jan 5, 2022 at 10:28 AM Will Senn <will.senn@gmail.com> wrote:

On 1/4/22 7:35 PM, Warner Losh wrote:

1. It's not going "full" screen, even with TERM=vt100 or TERM=ansi set (not that I was surprised, but it'd be nice)...

What does /etc/termcap look like?

 

All right, I'm getting warmer. I tried changing ttys to various speeds, and stty 9600, per Clem, Then, I looked at termcap, and saw that there weren't any ansi or vt100 entries (duh), so then I tryed vt50 and vt52 modes:

vt50:

HJ






  ~
  ~
  ~
  AAAA




      :q

vt52:

Y7 HJY- ~
        ~
        ~
        ~
        ~
        ~
        ~
        ~
        ~
        ~Y, Y7 :q

Here are the termcap entries. I compared with termcap in svr2, which has vt50,vt52, and vt100:

v7:

vh|vt50h|dec vt50h:\
        :bs:cd=\EJ:ce=\EK:cl=\EH\EJ:cm=\EY%+ %+ :co#80:li#12:nd=\EC:\
        :pt:sr=\EI:up=\EA:
v2|vt52|dec vt52:\
        :bs:cd=\EJ:ce=\EK:cl=\EH\EJ:cm=\EY%+ %+ :co#80:li#24:nd=\EC:\
        :pt:sr=\EI:up=\EA:

svr2:

d0|vt100|vt100-am|vt100|dec vt100:\
        :cr=^M:do=^J:nl=^J:bl=^G:co#80:li#24:cl=50\E[;H\E[2J:\
        :le=^H:bs:am:cm=5\E[%i%d;%dH:nd=2\E[C:up=2\E[A:\
        :ce=3\E[K:cd=50\E[J:so=2\E[7m:se=2\E[m:us=2\E[4m:ue=2\E[m:\
        :md=2\E[1m:mr=2\E[7m:mb=2\E[5m:me=2\E[m:is=\E[1;24r\E[24;1H:\
        :rs=\E>\E[?3l\E[?4l\E[?5l\E[?7h\E[?8h:ks=\E[?1h\E=:ke=\E[?1l\E>:\
        :rf=/usr/lib/tabset/vt100:ku=\EOA:kd=\EOB:kr=\EOC:kl=\EOD:kb=^H:\
        :ho=\E[H:k1=\EOP:k2=\EOQ:k3=\EOR:k4=\EOS:ta=^I:pt:sr=5\EM:vt#3:xn:\
        :sc=\E7:rc=\E8:cs=\E[%i%d;%dr:
d1|vt100|vt100-nam|vt100 w/no am:\
        :am@:xn@:tc=vt100-am:
d2|gt42|dec gt42:\
        :cr=^M:do=^J:bl=^G:\
        :le=^H:bs:co#72:ns:li#40:os:
d3|vt132|vt132:\
        :al=99\E[L:dl=99\E[M:ip=7:dc=7\E[P:ei=\E[4l:im=\E[4h:xn:dN#30:tc=vt100:
d4|gt40|dec gt40:\
        :cr=^M:do=^J:bl=^G:\
        :le=^H:bs:co#72:ns:li#30:os:
d5|vt50|dec vt50:\
        :cr=^M:do=^J:nl=^J:bl=^G:\
        :le=^H:bs:cd=\EJ:ce=\EK:cl=\EH\EJ:co#80:li#12:nd=\EC:ta=^I:pt:up=\EA:

Here's the list of available terminals culled from /etc/termcap from v7 and the buggy/untested list included in termcap:

dumb, lsi adm3/adm3a/adm31/adm3a, concept100/concept100rv, hp2645, dm1520/dm2500/dm3025/3025a, dec gt40/gt42/vt50/vt50h/vt52, decwriter I/decwriter II, diablo 300s, hazeltine 1500/1510/2000, Infoton 100/400/KAS, fox 1100, owl 1200, tektronix 4014, teleray 1061, terminet 1200/300, tty33/37/43, ti silent 700/745, xitex sct-100, beehiveIIIm, tvi912/tvi920, ttyWilliams, infoton|400|infoton 400

buggy -dm2500  
Untested - gt40, gt42, vt50, vt50h, dw1, dtc300s, gsi, infoton, fox, tk4014, t1061, 1200, 300, tty33, tty37, tty43

I don't suppose any of these look like reasonable approximations of something I have available in Terminal/xterm?

Will