23 May
2012
23 May
'12
11:18 a.m.
But if you already have a scanner, known to work, and
don't have the
parts you mention, or don't have the "model engineer's workshop"
tools...then I have trouble seeing anything wrong with using the
scanner.
Well, the largest scanner you are likely to have is an A3 one (or
whatever the equivalent is). So perhaps 17" on the long axis. Paper tape
is punched at 10 characters per inch, so you'd get 170 bytes off the tape
per scan. And then you'd have to reposition the tape. Joining up the
scans is going to be a problem since chracters could be repeated, you
might be able to go by any printing on the tape if you are lucky.
It's still not all that easy (a lot harder for _me_ tham making a tape
reader from scratch). And I think the read speed would be pretty low.
Including repositioning the tape by had, I couls see it taking 17 seconds
per scan (scan + reposition). That's only 10 chracters per second, That's
ASR33 kiod of speeds. A good optical reader will do 500-1000 cps.
Of course you could build somethign to winde the tape past the scanner,
but that is almost as much work as making a complete reader.
Much of the complexity -- certainly mechanical complexity -- was to be
able to stop the tape on the current character and restart it again
smoothly. This would not be needed if you are simply reading tapes into a
computer and archiving them on disk or similar if the computer can handle
the data reate with no problesm (I would hope any modern PC could handle
input data at 1000 bytes/second and could buffer 120K or so (length of a
paper tape reel) in RAM).
That would, for example, be my own case - I probably
could kludge
something together to pull paper tape past phototransistors, but (a) it
would be a kludge, (b) I don't have the phototransistors, and (c) I
My projects would be severely limited if I only used components I kept in
stcok...
don't have (I would have to design and build - not
difficult, but it
would have to be done) the electronics to interface the thing to a
computer. I do, however, have a scanner that needs nothing more than
plugging in of wires to work fine.
And software to process the scanned images....
-tony