Talk:Sketchpad

Untitled
Hello! was it actually possible to draw with the sketchpad using the light pen? The display was a vector graphics display, where you can only point to positions that are actually hit by the e-beam. (background positions cannot be determined?) — Preceding unsigned comment added by 129.13.73.141 (talk) 20:36, 6 February 2007 (UTC)
 * Yes, there are various techniques for finding the pen when it isn't pointing to an existing dot or vector. The approach used for free-hand drawing if the pen location was "recently known" and is not likely to have moved far is to draw a cluster of points or vectors around the last known location, in an increasing area until the pen is found.  If the pen location is completely unknown, filling the screen with "white noise" dots will find it quickly.  Both techniques were used on the DEC PDP-1 with Type 30 point-plot display, so they were probably used on TX-2 as well.  --Brouhaha 00:14, 7 February 2007 (UTC)
 * thank you! — Preceding unsigned comment added by 129.13.73.141 (talk) 13:20, 8 February 2007 (UTC)

History
Greetings. After a struggle I restored the History section. Corrections would be most welcome. I had better write a stub biography for Dr. Hanratty. -SusanLesch (talk) 17:05, 17 March 2013 (UTC)

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History section
The history section says "A considerable amount of work was required to make the TX-2 operate in interactive mode with a large CRT screen. When Sutherland had finished with it, it had to be reconverted to run in batch mode again." This statement is questionable as the TX-2 was a computer which was explicitly created for research on interactive computer usage. Even its predecessor, the TX-0, already had a CRT and a light gun, research in the CAD field continued an Lincoln Lab, and a film about Sketchpad which was created a few years later and which can be found on Youtube shows the system in perfectly working order, so it cannot have been "reconverted to run in batch mode again.".

Could someone with perhaps more knowledge about the system check that and maybe correct the statement? Winfel (talk) 17:28, 26 February 2019 (UTC)


 * I share the scepticism of @Winfel on this. On the TX-2 what we would today call device drivers were part of the user program.    Sutherland's thesis and other papers (and the video) describe the operation of Sketchpad.   Sketchpad routinely used the CRT (interactively_) and paper and magnetic tape (for data storage and offline plotting).  None of these peripherals seem in principle to require modification or reconfiguration to switch between Sketchpad and other usage.
 * The only changes I can think of which could be needed would be (1) changes to the priority plugboard and (2) the F-register configuration in the boot code. (1) might have been needed to adjust what we'd describe today as the relative priority of the sequences (threads) serving I/O for each device.  On the TX-2, I/O could fail if a sequence didn't yield the CPU soon enough for the needs of a device (either because of its high priority or because it was executing instructions with the hold bit set).  (2) could have been needed as the F-register setup used for ATLAS was different to that used for the base system.  Hardware changes to the boot code in plugboard B could achieve this, but you can just as easily achieve it in user code.
 * These are just suppositions based on reading reference information about the computer itself, I haven't ever used or seen the real machine, nor talked to anybody who might be considered a primary source.  I too would like to learn more about the basis for this remark about the need for things to be "reconverted", though. JamesYoungman (talk) 13:42, 26 March 2022 (UTC)
 * Photographs released to me by Lincoln Laboratory on 2022-10-31 show that by 1975 the CRT and light pen were gone. So at some point it clearly became impossible to run Sketchpad on the TX-2, even if you reversed the (toggle-switch configuration which sets up the) F-memory changes for APEX.  But I haven't yet seen evidence that much reconfiguration was needed at the time Sutherland was working on Sketchpad.   I have updated the article to very briefly mention removal of the CRT. JamesYoungman (talk) 14:11, 6 November 2022 (UTC)

Sketchpad's alleged inspiration for the oN-Line System
Hello. I'm writing an essay on Sketchpad and came across the statement in the 'History' section that Sketchpad inspired Douglas Engelbart's oN-Line System (NLS). Engelbart mentions Sutherland and his work on Sketchpad (without naming it) in his 1962 paper 'Augmenting Human Intellect: A Conceptual Framework' in the section titled ‘Other Related Thought and Work’ but he does not mention it as an inspiration. Does anyone know or have sources on where this idea comes from? Jogll1 (talk) 18:05, 30 November 2023 (UTC)

Music
It's fun and cool 😎 170.39.151.173 (talk) 05:19, 30 March 2024 (UTC)