Wanted, Papertape Reader for Archiving Tapes

Tony Duell ard.p850ug1 at gmail.com
Tue Apr 28 11:56:58 CDT 2020

On Tue, Apr 28, 2020 at 5:01 PM Bill Degnan via cctech
<cctech at classiccmp.org> wrote:
> Hi - COVID project.... I have been attempting to read some old Honeywell
> DDP-516 papertapes using the OP-80A or Teletype reader but it's inefficient
> and I don't want to damage the tapes.  Does anyone have a reliable
> papertape reader for sale, or recommend one currently out there on Ebay,
> for the purpose of archiving papertapes of any kind safely and reliably.  I
> have a reasonable budget.  I have a lot of tapes that need to be archived,
> so I'd want one that I can interface with to capture into TAP files or what
> I would call a raw dump listing of the data in 8-bit Hex.   MITS, SWTPc,
> Z80 stuf, PDP 8, PDP 11, Honeywell, etc.

All the paper tape readers I've seen simply give you the raw 8 bit
bytes (hole = 1, no hole = 0) off the tape. It's up to you to turn
that into whatever sort of file you want.

There are 3 main types of paper tape reader :

Mechanical. Like the one in the Teletype Model 33 ASR. The tape is fed
by a sprocket wheel and the holes are sensed by pins that come up
through the tape (called 'Peckers' in the manuals for Creed
teleprinters...). These readers are slow and hard on the tape. The
only time I'd use one would be to demonstrate how they work and why I
don't normally use them

Sprocket fed optical. The tape is moved by a sprocket working on the
feed holes, but the data holes are sensed by a light source and an
array of optical sensors. Much kinder to the tape (in general if the
tape jams the sprocket holes get ripped but they can be repaired, the
data holes are undamaged) and faster. Often the feed holes are also
sensed optically to provide the timing reference. Speeds between 30cps
and 120 cps are typical.

Capstan fed optical. By far the kindest to the tapes. The tape is fed
by a (smooth) capstan and pinch roller. The holes are sensed by a
light source and array of optical sensors, including the feed holes
which provide the timing reference. The HP2748 is a common-ish example
of this type of unt. I personally like (and use) the UK-built Trend
readers (HSR500, a bidirectional 500cps unit and UDR700, a
unidirectional machine that runs at 700cps). The nice part of the
Trend design is that they have 2 sensors on the feed track 2.5
characters apart. The data strobe occurs when the one in line with the
data hole sensors is brighter (by a certain amount) than the other
one. A weighted mean of the values from those 2 sensors gives the
threshold for the data hole sensors. The result is that they will read
just about anything. I am pretty sure the manual for the HP2748 is on
the Australian HP museum site. I offered the manuals for the Trend
units a couple of years back but nobody was interested then, they are
too large for me to send now (only when lockdown is lifted and the
local library reopens).

I doubt you'll find a Trend reader (actually I don't think there was a
60Hz mains version of the UDR700 although there seems to have been one
for the HSR500) but the HP2748  might turn up if you're lucky.


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