29 Jul
2020
29 Jul
'20
6:23 p.m.
Correct, the DSI NC2400 can be set up for different levels. It does require
a mechanical changeout for the punch, I think it's just a guide swap on the
reader. It's stepper feed but if you set it up for 2400 bps (default) and
let it run, tape motion is smooth and continuous.
HP 2100 series optical readers use a clutch to engage a constantly-running
drive motor, I haven't used my HP reader in a while (interfaced to S-100
through a custom card) but I seem to remember being able to keep the brake
from engaging with one of the control lines. Probably
not a common enough
reader though.
Thanks,
Jonathan
On Wed, Jul 29, 2020 at 9:17 PM Eric Moore via cctalk <cctalk at classiccmp.org>
wrote:
Absolutely would be good to have. I would prefer a
slow smooth pull through
the reader than slow and jerky or fast and smooth which are my current
options.
There are some kit paper tape readers out there that just need a pinch
roller added to be ideal.
On 5, 6, and 7 bit tape, I believe the DSI NC2400 which a number of people
have is adjustable width. That said, a kit that came with a variable width
optical read head and a variable speed smooth pinch roller with an RS232
interface would likely find a market with hobbyists. No hard brake needed
for archival purposes, but definitely a softer break to fairly quickly stop
the tape if something goes wrong.
-Eric
On Wed, Jul 29, 2020, 19:43 Paul Koning <paulkoning at comcast.net> wrote:
at
> On Jul 29, 2020, at 6:52 PM, Eric Moore <mooreericnyc at gmail.com>
wrote:
...
A couple notes:
1) My reader when set to lower baud rates physically stops and starts
the reader.
This jerks the tape and causes vibrations that can be severe some speeds.
Some readers do this at all speeds. For example, any stepper motor is by
definition a start/stop drive at any speed. Fast optical readers may run
continuously if you let them, but that's worth a careful check.
Especially
since some of the high speed readers have very
serious brake systems,
good
for their original application but not at all for
our purposes. I've
seen
tape readers specified at 1000 cps or better that
are capable of stopping
at any point, starting up again, and reading the next character. So they
are doing 100 inches per second and stopping within 1/20th of an inch.
Ouch.
The best kind of archival tape readers would have an adjustable tape path
so you can read any of 5, 6, 7, or 8 channel tape. While 6 and 7 is
uncommon it does exist. 6 is probably least interesting, at least the
only
application I know is typesetting, not
computing.
I've been thinking a newly constructed optical tape reader with
continuous
motion (no brakes), capstan drive, and slow ramp
start/stop would be
ideal
and with today's technology quite easy to
make.
paul