Comments on: Teaching an Almost 40-year Old UNIX about Backspace

By: Yoshi128k

Yoshi128k — Thu, 29 Feb 2024 03:36:43 +0000

I made the requisite patches to the system source code and rebuilt the kernel, but it panics when I attempt to boot it (my old kernel still works, however). Is it possible I missed a step, or did the kernel compilation wrong?

By: Eric Hanneken

Eric Hanneken — Tue, 07 Apr 2020 00:06:13 +0000

In reply to Roy. Yes, I used diff -e to generate the embedded ed(1) scripts.

By: Roy

Roy — Mon, 06 Apr 2020 23:57:00 +0000

In reply to Eric Hanneken. diff -e ?

By: Eric Hanneken

Eric Hanneken — Mon, 06 Apr 2020 21:52:27 +0000

In reply to xorhash.

I created a shell script to patch the source using ed(1):

https://gist.github.com/ehanneken/2413ec505a1e9c18f80a7fd3a081b99e

By: Eric Hanneken

Eric Hanneken — Mon, 06 Apr 2020 21:39:32 +0000

In reply to xorhash.

I wrote a shell script that uses ed(1) to patch the source code:

cd /usr

ed ./src/cmd/getty.c <<'EOE'
12c
struct tchars tchars = { '\003', '\034', '\021', '\023', '\004', '\377' };
.
8,9c
#define ERASE '\177'
#define KILL '\025'
.
w
q
EOE

ed ./src/cmd/login.c <<'EOE'
46,47c
ttyb.sg_erase = 0177;
ttyb.sg_kill = 025;
.
w
q
EOE

ed ./sys/dev/tty.c <<'EOE'
559a
* DEL is just a very fancy backspace today.
* However, just reducing colp by one is insufficient.
* We need to send an actual ^H.
* We're taking this opportunity to also rub out the
* previous character.
*/
if (c==0177) {
ttyoutput(010, tp);
ttyoutput(' ', tp);
ttyoutput(010, tp);
return;
}
/*
.
w
q
EOE

ed ./sys/h/tty.h <<'EOE'
84c
#define CINTR 003 /* ctl-c */
.
82c
#define CKILL 025
.
80c
#define CERASE 0177 /* default special characters */
.
w
q
EOE

By: Rhialto

Rhialto — Wed, 31 Jan 2018 23:26:40 +0000

A simple trick I’ve read (I haven’t tried it, but it sounds like it should work), is to use tar to write to a disk device. Outside the SIMH instance it is of course a file, and you can use tar on that file too. It just needs to understand the old V7 tar format.
Or otherwise you can do it one plain file at a time (although that might get tricky with detecting the end of it).

By: Eric Olson

Eric Olson — Mon, 29 Jan 2018 17:42:43 +0000

It is possible to get tmux to pass crtl+h for backspace and proceed without recompiling code for either R7 Unix or tmux. Details are at my thread Historic Unix R7 using SIMH on the Raspberry Pi forum

https://www.raspberrypi.org/forums/viewtopic.php?p=1055855#p1056719

This thread also details how to enable the high-speed DZ11 serial port driver in R7 and connect to those ports remotely using ssh.

By: xorhash

xorhash — Thu, 18 Jan 2018 11:01:40 +0000

In reply to DOS. That's pretty convenient. Good find! It also gives me an idea. I thought I was done with V7, but here we go again.

By: DOS

DOS — Thu, 18 Jan 2018 10:33:11 +0000

In reply to Alexander Voropai. Thanks! I found that project, but those first two tools are missing from the README.md so I didn't notice them. I see that they support multiple files per tape as you'd hope.

By: Alexander Voropai

Alexander Voropai — Thu, 18 Jan 2018 10:08:44 +0000

In reply to DOS.

JFYI there are also a “standard” SIMH tools
https://github.com/simh/simtools
( simtools/converters )
mksimtape – creates a SIMH tape
( simtools/extracters )
rawtap is extracter/creator
mtdump – dumps a tape structure