2 ms·
It was a bit different with the IBM 1403 printer on the IBM 1401 computer. You added a suffix to the write line instruction to suppress the line feed. This opti
by kens 8y ago
It was a bit different with the IBM 1403 printer on the IBM 1401 computer. You added a suffix to the write line instruction to suppress the line feed. This optional "space suppression" feature cost $63.
As far as I can tell, using a '+' in the first column to overprint was a Fortran thing, known as Fortran Carriage Control.
One entertaining feature of the 1403 was that form feeds were controlled by a 12-column paper tape. By punching holes in the tape, you could quickly form feed to 12 different positions on your page. (This was useful for pre-printed forms.) The only problem was if you did a form feed and there wasn't a hole in that column in the paper tape, the printer would feed at high speed through the entire box of paper without stopping. (The 1403 used a hydraulic motor for high-speed form feeds. If you see hydraulic fluid under the printer at the Computer History Museum, that's why.)
- chiph 8y agoHow did the 1403 start & stop the paper advance? Once the paper gets moving, there's a lot of inertia there. Was there an air bladder in the hydraulic line to absorb fluid-hammer from the rapid pressure changes? One of the printers I worked on in the USAF had electromagnetic clutches - one would engage to hold the paper in place while the other would open to disengage the drive belt. To move the paper, the "hold" clutch would disengage and the "drive" clutch would engage for just long enough to move it the required distance. And then the clutch action would reverse (hold clutch engage, drive clutch release) to stop the paper's motion. After a while, the clutch material would wear out and you would get the infinite form-feed. Edit: For the curious, this was taken at the school at Sheppard AFB in 1983: https://imgur.com/a/J74K6wM https://imgur.com/a/J74K6wM
- kens 8y agoThe 1403 has electrically-controlled valves to send fluid from the constantly-running pumps to the hydraulic motor to do a space (line feed) or skip (form feed). There's a back pressure bypass valve that relieves the pressure when the printer advance stops. The 1403 Field Engineering manual goes into great detail on the hydraulic system, starting at page 56. The momentum when stopping is described on page 62. Link: http://ibm-1401.info/0KenShirriff/IBM_Field_Engineering_Manual_of_Instruction_1403_Printers_225_6492_3.pdf http://ibm-1401.info/0KenShirriff/IBM_Field_Engineering_Manu...