12 Mar
2002
12 Mar
'02
4:33 a.m.
Date: Sat, 09 Mar 2002 10:59:04 -0700
From: Ben Franchuk <bfranchuk(a)jetnet.ab.ca>
X-Accept-Language: en
To: classiccmp(a)classiccmp.org
Subject: Re: Blank Paper Tape Question (P.S.)
Sender: owner-classiccmp(a)classiccmp.org
Lawrence LeMay wrote:
The TTY is the LOW speed punch/reader ... 10 CPS.
The high speed reader is 300 CPS for the PDP-8.
The problem with paper tape
on the PDP-8 at least is that you had to read a character at a
time. Read char... process ... read. This meant the paper tape
had to stop the tape on every character. Reading the tape is
not the problem ... stopping was.
You know, at 300 char/sec there is more than 3000 microseconds
between characters. Plenty of time for even a PDP-8 to execute
a thousand or so instructions.
The next challenge is to write a program to duplicate paper tapes,
high-speed reader at 300 c/s to high-speed punch at 50 c/s. Keep the
punch running at full speed while reading in bursts to keep ahead of
the punch.
carl
--
carl lowenstein marine physical lab u.c. san diego
clowenstein(a)ucsd.edu
A low speed punch 10 cps vers a high speed punch
50 cps could be a important cost factor. Now if you
had black paper tape one could zap out the holes
with a laser giving you a very high speed punch.
Since the punching speed does limit paper
tape to a practical limit of about 8kb was there
any really large paper tape programs? 4K focal on
a TTY was as long a program that I ever loaded from paper
tape ... 20 minutes.
Well, a good optical reader can read 400 characters per second. Correct me
if i'm wrong, but that seems like 4096 bytes takes 10.24 seconds to read
in. Assuming its not a 30 year old tape that vaporizes at that speed ;)
-Lawrence LeMay