21 Jul
2025
21 Jul
'25
1:44 a.m.
Hello all,
What teleprinter models were used at Bell Labs, particularly by the Unix groups? Judging
by troff escape sequences, it expected a Teletype Model 37, and early all-caps support
implies Model 33 usage. But I don’t have a sense of what users and the core developers
used.
I am working on building a Teletype Model 37 ASR emulator for my PiDP-11 with the goal of
replicating the early Unix experience as accurately as possible without physical hardware.
As I get deeper into research, I’ve learned of a variety of configuration options beyond
what the operator could configure with buttons, e.g., sub-models which come with different
components, optional components which can be installed later, and features that can be
configured by a craftsman. Here are some examples:
- Two-color was optional
- The shift-out character set was configurable
- An ASR could come without a tape reader/puncher
- Half-line forward and reverse was optional
- Character sizes varied, e.g., 72 chars per line at 10 chars per inch, adjustable up to
80 per line; or 86 per line at 12 per inch
- The paper could be roll paper (friction feed)or flat-folded, form-feed paper with
marginal perforations (sprocket feed)
- Paper sizes varied, e.g., 3 to 8-1/2 wide or, for sprocket feed, up to 11 inches long
and 9-1/2 wide
- Some printed control characters; most didn’t
- Holding a key could be configured to repeat the character
- They could operate half-duplex (transmitted data is copied by the sender) or full-duplex
(only received data is copied)
- They could receive and transmit at various speeds
That’s a lot of options and it’s not exhaustive.
The Model 37 product catalog[0] has tables of many configurations and their catalog
numbers. Is there a list of the teleprinters purchased by Bell Labs? With that, I could
possibly narrow it down like how Warner Losh identified the PDP-7 model used for Unix V0.
Thanks!
Thalia Archibald
[0]:
https://ia800702.us.archive.org/32/items/TNM_Model_37_terminal_product_cata…
[1]: https://bsdimp.blogspot.com/2019/07/the-pdp-7-where-unix-began.html
21 Jul
21 Jul
3:18 a.m.
On Mon, 21 Jul 2025, Thalia Archibald via TUHS wrote:
[...]
I am working on building a Teletype Model 37 ASR
emulator for my PiDP-11
with the goal of replicating the early Unix experience as accurately as
possible without physical hardware.
The fount of all wisdom and knowledge on Teletypes would be the
"Greenkeys" mailing list, over at
List-Id: "Discussion of older radio teletype (RTTY) gear
"<greenkeys.mailman.qth.net>"
It's RTTY (Radio Teletype) related i.e. "ham" radio, but there's a lot
of
knowledge over there.
-- Dave
29 Jul
29 Jul
2:11 p.m.
On Mon, Jul 21, 2025 at 01:44:26AM +0000, Thalia Archibald via TUHS wrote:
The Model 37 product catalog[0] has tables of many configurations and their catalog
numbers. Is there a list of the teleprinters purchased by Bell Labs? With that, I could
possibly narrow it down like how Warner Losh identified the PDP-7 model used for Unix V0.
Not quite what you are asking, Dennis Ritchie provided a list of
terminals he used at home.
From alt.folklore.computers Jan 13, 1993
https://groups.google.com/g/alt.folklore.computers/c/qwI7XHPBu-s/m/NgGcn_Si…
"for the sake of history, here is the sequence of terminals I have used
at home, all paid for by my employer. Dates are approximate.
1968: IBM 1050 (14.5 cps)
1970: Teletype 37 (15 cps)
1975: GE Terminet 300 (30 cps)
1978: HP 2621 (120 cps)
1983: Jerq (Blit) (120, later 960 cps)
1990: Gnot (Plan 9) (960 cps)
1992: Gnot (Plan 9) (8192 cps ISDN)"
When John Lions was at Bell Labs on sabbatical:
"Up till now I have been using a tty 43 (this listing)
...
there is a noticeable preponderance of hard copy and lack of CRT terminals."
John Lions, 15 August 1978
AUUGN Vol 1, No 1, p 21
from Dennis Ritchie in alt.folklore.computers Feb 12, 2011
https://groups.google.com/g/alt.folklore.computers/c/TbnWa4H0qS0/m/RUFInaTm…
"Unix in 1969 was mostly written on a TTY33. Our PDP-7 also had a
full-ASCII keyboard that was part of the locally-built Graphics-II
processor attached to the PDP-7, used for Space Travel, for example,
and also for development once Unix was self-supporting."
Dennis mentions an ASR33 for the initial PDP-11 in:
https://www.tuhs.org/pipermail/tuhs/2002-September/002162.html
https://www.tuhs.org/pipermail/tuhs/2002-September/002181.html
More terminal discussions from alt.folklore.computers:
Oct 31, 2001
https://groups.google.com/g/alt.folklore.computers/c/2hIR4udbSD0/m/peXf7MB7…
May 10, 2005
https://groups.google.com/g/alt.folklore.computers/c/yUlJLKto-LQ/m/0la-n5KC…
on the IBM 2741 as used with CTSS and Multics
4:16 p.m.
Explaining John’s comment.
I requested some reports from UNSW Archives in 2021.
This one, by Keith Titmus in 2000, was a short history of Prof Murray Allen,
who'd hired John Lions and Ken Robinson in 1972.
08_224_01 MW Allen_Keith-Titmus_2000
There were some Decwriters at UNSW, but mainly ’Serge’ Terminals in 1978.
Designed and built by the local staff (Serge P).
They were in use for 12 years.
The paint wore off the cabinets,
but they’d bought expensive ‘hall effect’ keyboards for them and they kept on and on…
Elsewhere:
In 1976, "UNSW, by end of year, boasted 200 registered users" on their
Unix system.
On 30 Jul 2025, at 00:11, Jonathan Gray
<jsg(a)jsg.id.au> wrote:
When John Lions was at Bell Labs on sabbatical:
"Up till now I have been using a tty 43 (this listing)
...
there is a noticeable preponderance of hard copy and lack of CRT terminals."
John Lions, 15 August 1978
AUUGN Vol 1, No 1, p 21
===============
In 1972, Murray was involved with the design of VISICOM, an ME thesis by Serge Poplavsky.
In 1976 Murray directed the building of 50 terminals for the newly created computing
facilities.
The first terminal laboratories were the forerunner of the computer laboratories that are
now existent.
The initial batch of terminals were a hard wired construction,
while the next batch of 25 used an early version of microprocessor - the Motorola MC6802,
and the third terminal version used the Motorola MC6809.
The terminals were in use until the first workstations,
the Apollo using the Motorola MC68020 microprocessor,
began replacing them in 1988.
===============
--
Steve Jenkin, IT Systems and Design
0412 786 915 (+61 412 786 915)
PO Box 38, Kippax ACT 2615, AUSTRALIA
mailto:sjenkin@canb.auug.org.au http://members.tip.net.au/~sjenkin
6:06 p.m.
At Hopkins we had a KSR37 which had the big ol’ NEWLINE key and did
stuff with the ESC 8 and 9 stuff that nroff spewed directly. It even
had a greek box that was well integrated into eqn.
It largely got supplanted with the faster and nicer printing diablo and
even that fell to the versatec troff emulators and eventually to things
like the Imagen laser printers.
I procured my own Model 37 from the Rocky Flats Nuclear Site surplus
department. It had a big sidecar paper tape punch reader.
-Ron
6:34 p.m.
An extant memento of my home TTY 37 is a stack of fanfold paper that
accommodated artwork by children and grandchildren. About 1/4".remains
for potential great-grandchildren.
Doug
On Tue, Jul 29, 2025 at 2:06 PM Ron Natalie <ron(a)ronnatalie.com> wrote:
At Hopkins we had a KSR37 which had the big ol’ NEWLINE key and did stuff with the ESC 8
and 9 stuff that nroff spewed directly. It even had a greek box that was well integrated
into eqn.
It largely got supplanted with the faster and nicer printing diablo and even that fell to
the versatec troff emulators and eventually to things like the Imagen laser printers.
I procured my own Model 37 from the Rocky Flats Nuclear Site surplus department. It had
a big sidecar paper tape punch reader.
-Ron
30 Jul
30 Jul
6:02 a.m.
New subject: greenbar fanfold paper - anyone else miss it?
Douglas McIlroy <douglas.mcilroy(a)dartmouth.edu> wrote:
An extant memento of my home TTY 37 is a stack of
fanfold paper that
accommodated artwork by children and grandchildren. About 1/4".remains
for potential great-grandchildren.
Doug
I really miss 11" x 17" greenbar fanfold paper. It was wonderful
for printing out program listings and reviewing code. One could
make notes on the side of the code, flip back and forth between
different files to see how different data structures were used,
and so on. It was great.
That's how I first learned the gawk code (MUCH smaller at the
time). I printed out the whole thing and read through it, making
notes.
Sigh. The good old days.
Arnold
P.S. Some years ago I went through the binders on my bookshelves to
get rid of things. From that I have a stack about 4 feet high of letter
paper printed one-sided on a laser printer, waiting for use by future
grandchildren. Sadly, not one of my kids is married. (These days my
laser printer does duplex; anything I don't need goes into recycling.)
Whatever. We now return you to our regularly scheduled reminiscing.
7:27 a.m.
New subject: greenbar fanfold paper - anyone else miss it?
On Tuesday, July 29th, 2025 at 11:02 PM, arnold(a)skeeve.com <arnold(a)skeeve.com>
wrote:
Douglas McIlroy douglas.mcilroy(a)dartmouth.edu wrote:
Getting COFFy but TUHS bcc, I intend for an upcoming software analysis project to print
paper copies and comb over things very finely with a pen. The project is a thorough
Lions-esque analysis of Super Mario Bros. 3 for the Famicom/NES. I hope once I'm
"done" with my disassembly of it to first print a full copy to sit at coffee
shops with and annotate and then eventually produce something comparable to the
Lions' publication but the SMB3 code and an accompanying commentary (typeset with
troff of course). How grand it would be to have the printouts on true terminal fan-fold.
Recently I did spot a Ti hardcopy terminal sitting in a junk pile at the university, I am
forever kicking myself for not grabbing it...it did use some sort of continuous paper, but
looked to have a reel rather than fan-fold uptake, I didn't make note of the model,
only that it had a typical DB-25 (presumably RS-232) serial jack. Granted if I'm
simply printing for analysis waiting for a terminal to print it is overkill...
- Matt G.
An extant memento of my home TTY 37 is a stack of
fanfold paper that
accommodated artwork by children and grandchildren. About 1/4".remains
for potential great-grandchildren.
Doug
I really miss 11" x 17" greenbar fanfold paper. It was wonderful
for printing out program listings and reviewing code. One could
make notes on the side of the code, flip back and forth between
different files to see how different data structures were used,
and so on. It was great.
That's how I first learned the gawk code (MUCH smaller at the
time). I printed out the whole thing and read through it, making
notes.
Sigh. The good old days.
Arnold
P.S. Some years ago I went through the binders on my bookshelves to
get rid of things. From that I have a stack about 4 feet high of letter
paper printed one-sided on a laser printer, waiting for use by future
grandchildren. Sadly, not one of my kids is married. (These days my
laser printer does duplex; anything I don't need goes into recycling.)
Whatever. We now return you to our regularly scheduled reminiscing.
12:27 a.m.
UNSW terminals mentioned briefly by John in:
Experiences with the UNIX Time-sharing System
Software-Practice & Experience, Vol. 9, No. 9, pp. 701-709, Sep 1979
"The remote-batch load absorbs about 5 per cent of the 11/70 and its
residual capacity is used to serve nearly 50 interactive terminals.
(Most of these are CRTs running at 2400 baud, that have been built
in-house to our own design; each incorporates a high-quality CRT display
and keyboard, and supports full ASCII 96 character set, and a graphics
mode)."
A photo with one? UNSW UNIKEN, 10 Sep 1982
https://nla.gov.au/nla.obj-257305977/view?sectionId=nla.obj-261273025
"Computer Science students using computer terminals under the
supervision of Associate Professor John Lions. There are some 70
terminals in the School's student labs, most of which have been designed
and built there."
A cropped colour version of this photo is used on the wikipedia page
for John Lions, but the unsw.edu.au source of it was removed.
A non-cropped colour version also appears on the cover of the
1979 UNSW Annual Report:
https://digitalcollections.library.unsw.edu.au/nodes/view/171706
References to a serge terminal can be found in:
TUHS Distributions/UNSW/92/ (UNIX Level 7 Source 25/3/81)
src/cmd/tbs/tbs.c
cmd/s.getty.c
On Wed, Jul 30, 2025 at 02:16:13AM +1000, sjenkin(a)canb.auug.org.au wrote:
Explaining John’s comment.
I requested some reports from UNSW Archives in 2021.
This one, by Keith Titmus in 2000, was a short history of Prof Murray Allen,
who'd hired John Lions and Ken Robinson in 1972.
08_224_01 MW Allen_Keith-Titmus_2000
There were some Decwriters at UNSW, but mainly ’Serge’ Terminals in 1978.
Designed and built by the local staff (Serge P).
They were in use for 12 years.
The paint wore off the cabinets,
but they’d bought expensive ‘hall effect’ keyboards for them and they kept on and on…
Elsewhere:
In 1976, "UNSW, by end of year, boasted 200 registered users" on their
Unix system.
On 30 Jul 2025, at 00:11, Jonathan Gray
<jsg(a)jsg.id.au> wrote:
When John Lions was at Bell Labs on sabbatical:
"Up till now I have been using a tty 43 (this listing)
...
there is a noticeable preponderance of hard copy and lack of CRT terminals."
John Lions, 15 August 1978
AUUGN Vol 1, No 1, p 21
===============
In 1972, Murray was involved with the design of VISICOM, an ME thesis by Serge Poplavsky.
In 1976 Murray directed the building of 50 terminals for the newly created computing
facilities.
The first terminal laboratories were the forerunner of the computer laboratories that are
now existent.
The initial batch of terminals were a hard wired construction,
while the next batch of 25 used an early version of microprocessor - the Motorola MC6802,
and the third terminal version used the Motorola MC6809.
The terminals were in use until the first workstations,
the Apollo using the Motorola MC68020 microprocessor,
began replacing them in 1988.
===============
--
Steve Jenkin, IT Systems and Design
0412 786 915 (+61 412 786 915)
PO Box 38, Kippax ACT 2615, AUSTRALIA
mailto:sjenkin@canb.auug.org.au http://members.tip.net.au/~sjenkin
12:56 a.m.
On Wed, 30 Jul 2025, Jonathan Gray wrote:
"The remote-batch load absorbs about 5 per cent
of the 11/70 and its
residual capacity is used to serve nearly 50 interactive terminals.
(Most of these are CRTs running at 2400 baud, that have been built
in-house to our own design; each incorporates a high-quality CRT display
and keyboard, and supports full ASCII 96 character set, and a graphics
mode)."
The Serge terminal was quite nice (heaps better than the Aussie
"Transdata" ones that we also used at the time); they had a switch on the
front which took it offline (by dropping CD?), and it made for a handy
scroll-lock, and so likely used hardware flow control?
-- Dave
1:15 a.m.
On Wed, Jul 30, 2025 at 10:27:23AM +1000, Jonathan Gray wrote:
"The remote-batch load absorbs about 5 per cent
of the 11/70 and its
residual capacity is used to serve nearly 50 interactive terminals.
I still remember, fondly (sort of) being in a terminal room with 50+
other students all hooked up to a 4MB VAX 780. The fondness was the
sort of bonding we all had from pulling all nighters to get stuff to
work (this was at UW-Madison, back then it was a hard core hacking
school, lots of Sun's kernel group came from Madison, including
Rusty (NFS) and Mojo (he wrote the 4.x VM system) and a bunch of
others).
The not so fond part was hit ^T over and over again (it gave you
a one line PS like output showing load) while your compiled seemed
swapped out forever.
The not fondness made me take out one of the very few loans I have had,
in 1985ish I borrowed $2000 to buy a Okidata CPM machine, it was a lot
slower than the VAX, but all the cycles were mine. I wrote a lot of
code on that machine. Including assembler versions of cp, rm, ls,
etc, each of which fit in 512 bytes because that was one sector on
a floppy disk, I didn't want to wait for more than one sector to
load. Fun times. Now my phone is like 10,000x faster and has
easily that much more memory.
--lm
7:18 a.m.
On Tuesday, July 29th, 2025 at 6:15 PM, Larry McVoy <lm(a)mcvoy.com> wrote:
On Wed, Jul 30, 2025 at 10:27:23AM +1000, Jonathan
Gray wrote:
Larry if you don't mind my curiosity, were these UNIX-y utilities sitting on top of
and using CP/M services or chomping at the hardware a little more closely? Or something
else?
- Matt G.
"The remote-batch load absorbs about 5 per
cent of the 11/70 and its
residual capacity is used to serve nearly 50 interactive terminals.
I still remember, fondly (sort of) being in a terminal room with 50+
other students all hooked up to a 4MB VAX 780. The fondness was the
sort of bonding we all had from pulling all nighters to get stuff to
work (this was at UW-Madison, back then it was a hard core hacking
school, lots of Sun's kernel group came from Madison, including
Rusty (NFS) and Mojo (he wrote the 4.x VM system) and a bunch of
others).
The not so fond part was hit ^T over and over again (it gave you
a one line PS like output showing load) while your compiled seemed
swapped out forever.
The not fondness made me take out one of the very few loans I have had,
in 1985ish I borrowed $2000 to buy a Okidata CPM machine, it was a lot
slower than the VAX, but all the cycles were mine. I wrote a lot of
code on that machine. Including assembler versions of cp, rm, ls,
etc, each of which fit in 512 bytes because that was one sector on
a floppy disk, I didn't want to wait for more than one sector to
load. Fun times. Now my phone is like 10,000x faster and has
easily that much more memory.
--lm
2:13 p.m.
On Wed, Jul 30, 2025 at 07:18:07AM +0000, segaloco via TUHS wrote:
On Tuesday, July 29th, 2025 at 6:15 PM, Larry McVoy
<lm(a)mcvoy.com> wrote:
It's been a long time but I can't imagine I reimplemented the file system
in 512 bytes. So I must have used something from CP/M. I didn't have the
chops to redo the file system at that time. I was still learning OS stuff.
The biggest thing I wrote on that machine was a dial in/terminal emulator/
file transfer tool I called quicknet. I kinda wish I still had that code,
my memory is that it was very pleasant.
--
---
Larry McVoy Retired to fishing http://www.mcvoy.com/lm/boat
On Wed, Jul 30, 2025 at 10:27:23AM +1000,
Jonathan Gray wrote:
Larry if you don't mind my curiosity, were these UNIX-y utilities sitting on top of
and using CP/M services or chomping at the hardware a little more closely? Or something
else? "The remote-batch load absorbs about 5 per
cent of the 11/70 and its
residual capacity is used to serve nearly 50 interactive terminals.
I still remember, fondly (sort of) being in a terminal room with 50+
other students all hooked up to a 4MB VAX 780. The fondness was the
sort of bonding we all had from pulling all nighters to get stuff to
work (this was at UW-Madison, back then it was a hard core hacking
school, lots of Sun's kernel group came from Madison, including
Rusty (NFS) and Mojo (he wrote the 4.x VM system) and a bunch of
others).
The not so fond part was hit ^T over and over again (it gave you
a one line PS like output showing load) while your compiled seemed
swapped out forever.
The not fondness made me take out one of the very few loans I have had,
in 1985ish I borrowed $2000 to buy a Okidata CPM machine, it was a lot
slower than the VAX, but all the cycles were mine. I wrote a lot of
code on that machine. Including assembler versions of cp, rm, ls,
etc, each of which fit in 512 bytes because that was one sector on
a floppy disk, I didn't want to wait for more than one sector to
load. Fun times. Now my phone is like 10,000x faster and has
easily that much more memory.
--lm
6:20 a.m.
Great rabbit hole, searching the UNSW archives.
Thanks for finding the 1979 Report.
The photo below would’ve been taken in the IBM 360 machine room after its removal.
On Elec Eng, 4th floor?
The raised flooring was for the IBM.
===============
PDP 11/70 Computer in the Department of Computer Science
<https://digitalcollections.library.unsw.edu.au/nodes/view/133051>
The new PDP 11/70 computer in the Department of Computer Science, including: Peter
Ivanov (seated), Ian Johnstone.
===============
On 30 Jul 2025, at 10:27, Jonathan Gray
<jsg(a)jsg.id.au> wrote:
A cropped colour version of this photo is used on the wikipedia page
for John Lions, but the unsw.edu.au <http://unsw.edu.au/> source of it was removed.
A non-cropped colour version also appears on the cover of the
1979 UNSW Annual Report:
https://digitalcollections.library.unsw.edu.au/nodes/view/171706
--
3:29 a.m.
On Wed, Jul 30, 2025 at 02:16:13AM +1000, sjenkin(a)canb.auug.org.au wrote:
Explaining John’s comment.
I requested some reports from UNSW Archives in 2021.
This one, by Keith Titmus in 2000, was a short history of Prof Murray Allen,
who'd hired John Lions and Ken Robinson in 1972.
08_224_01 MW Allen_Keith-Titmus_2000
There were some Decwriters at UNSW, but mainly ’Serge’ Terminals in 1978.
Designed and built by the local staff (Serge P).
Before that, there was the INTERGRAPHIC, used with an IBM 360/50.
Malcolm Macaulay
A low cost computer graphic terminal
https://dl.acm.org/doi/10.1145/1476589.1476688
"INTERGRAPHIC system built at the UNSW between 1964 and 1966 by
G. A. Rose under M. W. Allen. The design team included P. D. Jones,
T. Pearcey, R. B. Stanton and M. Macaulay"
https://www.austehc.unimelb.edu.au/tia/595.html
Pearcey of CSIR Mk1/CSIRAC fame.
An oral history of Murray Allen goes into Unix and Intergraphic.
Murray Allen interviewed by David Demant in the History of ICT in
Australia oral history project
https://trove.nla.gov.au/work/178430368
6:12 a.m.
Hi Team,
First time contributor, long time reader.
I am a different Serge to the one in this thread.
Been active in computing in AUS since the early 70s. Used Teletype KSR/ASR
33 from about 1973 to 1981. Many other CRTS, terminals as well.
These are my recollections. They may be flawed.
KSR 33 did NOT have a paper tape reader/punch. The Paper Tape punch and
reader were on the ASR33 model exclusively. These devices were mechanical,
ran at 110 Baud serial, typically in a 20 ma current loop for signalling.
Used ASCII. I do not know of any way to change the interface speed, only
ever saw 110. I have seen in magazines of the time, built in modems, but
none seem to have made it to Australia. The paper was typically a friction
fed via a platen. The interlock to stop multiple keys was done
mechanically. Fairly noisy. Wiki is not bad,
https://en.wikipedia.org/wiki/Teletype_Model_33
ASR/KSR 33 was a standard for all terminals in that era that used serial
ASCII.
The paper tape reader was used to bootstrap the OS to most minicomputers of
the era. There was a limit as to how much paper tape could be fed by the
internal feed mechanism and would often fail with a CRC check for larger
punched tape rolls. The reader and punch could be controlled by a key
sequence sent from the computer. Tape also ran at 110 Baud.
Used a cross section of mini computers, most DEC devices, right through to
PDP10 timesharing. DECWriters were very versatile and reliable across a
broad range of devices, more CRTS, and computers than I can remember.
Not sure if it helps.
On Wed, 30 Jul 2025 at 13:29, Jonathan Gray <jsg(a)jsg.id.au> wrote:
On Wed, Jul 30, 2025 at 02:16:13AM +1000,
sjenkin(a)canb.auug.org.au wrote:
Explaining John’s comment.
I requested some reports from UNSW Archives in 2021.
This one, by Keith Titmus in 2000, was a short history of Prof Murray
Allen,
who'd hired John Lions and Ken Robinson in
1972.
08_224_01 MW Allen_Keith-Titmus_2000
There were some Decwriters at UNSW, but mainly ’Serge’ Terminals in 1978.
Designed and built by the local staff (Serge P).
Before that, there was the INTERGRAPHIC, used with an IBM 360/50.
Malcolm Macaulay
A low cost computer graphic terminal
https://dl.acm.org/doi/10.1145/1476589.1476688
"INTERGRAPHIC system built at the UNSW between 1964 and 1966 by
G. A. Rose under M. W. Allen. The design team included P. D. Jones,
T. Pearcey, R. B. Stanton and M. Macaulay"
https://www.austehc.unimelb.edu.au/tia/595.html
Pearcey of CSIR Mk1/CSIRAC fame.
An oral history of Murray Allen goes into Unix and Intergraphic.
Murray Allen interviewed by David Demant in the History of ICT in
Australia oral history project
https://trove.nla.gov.au/work/178430368
12:04 p.m.
On Wed, Jul 30, 2025 at 04:12:51PM +1000, Serge Burjak wrote:
KSR 33 did NOT have a paper tape reader/punch. The
Paper Tape punch and
reader were on the ASR33 model exclusively.
KSR == Keyboard Send and Receive
ASR == Automatic Send and Receive
The paper tape is much like the paper roll used for player pianos,
where the paper roll "automatically" plays the piano without a human
at the keyboard. The concept predates the computer era by quite some time.
The paper tape reader was used to bootstrap the OS to
most minicomputers of
the era. There was a limit as to how much paper tape could be fed by the
internal feed mechanism and would often fail with a CRC check for larger
punched tape rolls. The reader and punch could be controlled by a key
sequence sent from the computer. Tape also ran at 110 Baud.
The PDP-8 RIM bootstrap loader:
7756 <Load PC>
6014 <deposit>
6011 <deposit>
5357 <deposit>
6016 <deposit>
7106 <deposit>
7006 <deposit>
7520 <deposit>
5357 <deposit>
7006 <deposit>
6011 <deposit>
5367 <deposit>
6016 <deposit>
7420 <deposit>
3776 <deposit>
3376 <deposit>
5357 <deposit>
0000 <deposit>
0000 <deposit>
<Load paper tape containing the BIN loader into ASR-35 teletype>
7756 <Load PC> <Run>
I got *really* good at toggling in the binary RIM loader into a
PDP-8/i. (I still have it mostly memorized after all of these
decades.) The RIM loader was less efficient (it used two characters
for each 12-bit word), and had no checksums. This could be used to
load the more sophisticated BIN loader that would use the full paper
width and with checksums, and which could read from the high-speed
paper tape reader, if you had that peripheral....
- Ted
16
days inactive
25
days old
16 comments
12 participants
participants (12)
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arnold＠skeeve.com -
Dave Horsfall -
Douglas McIlroy -
Jonathan Gray -
Larry McVoy -
Ron Natalie -
segaloco -
Serge Burjak -
sjenkin＠canb.auug.org.au -
Steve Jenkin
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Thalia Archibald -
Theodore Ts'o