Symbolics keyboard PN 365407
This is used in Symbolics 36xx series lisp machines , around 1985.
[see Lisp Machine Keyboards]
There are 3 revisions, A, B, C. Rev C had LEDs in the Caps Lock and Mode Lock keys.
here's a big photo 4000×3000
Rev A
bottom: Symbolics Keyboard PN 364000
The new one is more compact. [image source https://deskthority.net/keyboards-f2/the-lisp-keyboards-t98.html, by webwit]
Rev C
Rub Out key
2017-05-18 ScottBurson wrote
On an ASR33 Teletype, backspace simply moved the carriage one character position to the left.
Rubout was a different concept entirely. The ASR33 had a paper tape punch and reader. The Rubout character was 0x7F, i.e., it had all bits set. So, to “rub out” an erroneous character from the paper tape, you could back the tape up in the punch to the desired character (by pressing a button on the punch; there was no character that invoked this function) and hit Rubout; this would punch the tape at all seven holes, changing whatever character had been there to a Rubout. (The software ignored Rubout characters on input.)When the world moved on from Teletypes, it was natural for people to want a single keystroke that meant “delete the previous input character”. But there was evidently some divergence of opinion in the industry as to whether that should be Backspace or Rubout — notwithstanding that the ASR33's concept of Rubout didn't really map at all onto the new hardware.
[2017-05-19 from https://news.ycombinator.com/item?id=14367207]
2017-05-18 kps wrote:
notwithstanding that the ASR33's concept of Rubout didn't
really map at all onto the new hardware.If you are working with paper tape, Rubout (DEL in ASCII parlance), like every other code, advances the tape when punched. So, if the tape is a stream of characters, DEL erases the one under the cursor and leaves the cursor on the character formerly to the right. That is, Rubout/DEL is defined as a ‘forward delete’ operation, and that's something that remains useful. That leaves Backspace as the natural choice for entering ‘backward delete’ on a keyboard, at least after 1979 when you have the ANSI X3.64 escape sequences for explicitly nondestructive cursor keys. I think there's a reasonable argument for Backspace being nondestructive for overstrike effects (accents, underlining, APL, etc.), especially when received by a terminal, but I know none for changing the meaning of DEL.
Note the dedicated parenthesis keys.
Key Switch
It appears, there are different models of 365407, using different switches.
Hi-Tek Series 725 was Hi-Tek Corporation's DIN-compliant keyboard series, introduced in 1983; the name refers to how these keyboards are a maximum of 0.725″ from the desk surface.[1] "Series 725" also refers to the switches used in these keyboards.
2018-09-26 from https://deskthority.net/wiki/Hi-Tek_Series_725
ITW magnetic valve is a provisional name which refers to a type of electromagnetic switch patented by ITW and manufactured by ITW and Devlin.
2018-09-26 from https://deskthority.net/wiki/ITW_magnetic_valve
Jan 13, 2021
Keymacs
00:01 Keymacs A620N-88 (Alps SKCM Salmon)
00:19 Symbolics 365407 Rev. A (HiTek 725)
00:44 Symbolics 365407 Rev. C (ITW magnetic valve)
01:14 Symbolics 364000 Rev. C (Micro Switch SC)
Previous Model
The previous models is PN 364000, and is compatible to it.
