Another option is something like an op-80a where you can manually pull the tape across sensors making sure you don't damage it. Essentially a low tech version of what you guys described using a video camera.
The op-80a doesn't have a physical sprocket to break the tape, it uses the sprocket holes only for timing/triggering the character. Even if you don't have access to an one, they can be built pretty easily and the schematic is readily available on line. I keep one around just for such a purpose, though I really should put a microcontroller together to bit bang the parallel to serial or a simple UART so that I can hook it up to a modern computer. It would remove the middle step of reading it into my sol-20 and then dumping it to my laptop. Cheers, Corey corey cohen uǝɥoɔ ʎǝɹoɔ > On Jan 21, 2016, at 9:46 PM, Charles Anthony <charles.unix....@gmail.com> > wrote: > >> On Thu, Jan 21, 2016 at 6:21 PM, Jason T <silent...@gmail.com> wrote: >> >> On Thu, Jan 21, 2016 at 8:04 PM, Charles Anthony >> <charles.unix....@gmail.com> wrote: >>> For part 2, personally, I would take movies of the paper tape moving and >>> doing image analysis to recover that data; this occurs to me because I've >>> done a fair bit of image recognition software, so this solution may not >> be >>> feasible for all. If you sent me a sample movie, I would make a stab at >>> writing some data recovery software. >> >> I have heard of those approach and was thinking it may be a solution >> in cases where the tape is too fragile (and that's pretty likely >> here.) It would be well beyond my abilities but might make an >> interesting project for you or anyone else with the skills. > > > The general approach would be to have the tape backlit (on a piece of > glass, with a light source and and diffuser underneath ) and guide block > that the tape slides against so the holes move left-to-right but not up and > down. The camera is set up so that the tape fills the image as much as is > feasible. You start the camera, and slide the tape. Constant speed is not > important, but avoid backing up. > > Grab a frame from the movie. Figure out the approximate pixel coordinates > of the data and pin feed holes in the axis moving across the tape (eg, the > 1 bit is about 24 pixels from the top of the image, the 2 bit is about 47 > pixels from the top, etc). > > Process the movie a frame at a time. Grab a column of pixels from the > center of the image from top to bottom. Look at the pixels around where the > pin feed is, decide if they are light or dark. If light, the a character is > centered in the column. If not, move to the next frame. look at the pixels > around where each data bit is, and decide if the are light (punched) or > dark (unpunched). Write out that data. Skip frames until the pin feed > pixels go dark, and then skip frames until it goes light again; that will > be the next character. Repeat. > > The pin feed holes greatly simplify the process. This process is quite > analogous to reading multi-track magnetic media with a timing track. > > Test on a known tape. Debug. Run over damaged tapes; data recovered. > > -- Charles
