> Date: Sat, 09 Mar 2002 10:59:04 -0700
> From: Ben Franchuk <bfranchuk_at_jetnet.ab.ca>
> X-Accept-Language: en
> To: classiccmp_at_classiccmp.org
> Subject: Re: Blank Paper Tape Question (P.S.)
> Sender: owner-classiccmp_at_classiccmp.org
>
> Lawrence LeMay wrote:
> >
> > >
> > > 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
>
> 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_at_ucsd.edu
Received on Tue Mar 12 2002 - 12:33:47 GMT