Timeline for Why did 1970s front panels prefer momentary toggle switches to push buttons?
Current License: CC BY-SA 4.0
16 events
| when toggle format | what | by | license | comment | |
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| Jun 18, 2020 at 8:29 | history | edited | CommunityBot |
Commonmark migration
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| Sep 8, 2019 at 0:11 | answer | added | Julie in Austin | timeline score: 0 | |
| Sep 3, 2019 at 7:18 | history | edited | cjs | CC BY-SA 4.0 |
Clarify Altair/IMSAI switches
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| Sep 3, 2019 at 3:25 | history | edited | cjs | CC BY-SA 4.0 |
Clarify that momentary toggles default to "off"
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| Sep 3, 2019 at 3:10 | history | edited | cjs | CC BY-SA 4.0 |
Confirm that toggles were still SPST
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| Sep 3, 2019 at 2:08 | comment | added | cjs | @Nimbus, Yes, the two photographs are the 1620 and the PDP-1 mentioned and linked in the previous paragraph. You can click those links for bigger pictures and hopefully even sweeter memories. :-) | |
| Sep 2, 2019 at 20:30 | answer | added | Whit3rd | timeline score: 7 | |
| Sep 2, 2019 at 18:47 | comment | added | NimbUs | Just curious... isn't the 1st (top left) photograph above showing the console of an IBM 1620 by chance ? Or just my imagination ( sweet memories of days - and nights - in "her" company) | |
| Sep 2, 2019 at 9:32 | comment | added | cjs | @JeremyP The address/data switches are not momentary, but the "command" switches for examine etc. are. I've updated the post to better describe this. | |
| Sep 2, 2019 at 9:31 | history | edited | cjs | CC BY-SA 4.0 |
Improve explanation/description of non- vs. momentary contact switches
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| Sep 2, 2019 at 9:13 | comment | added | JeremyP | The switches in your bottom photo don't look like momentary toggles to me. They are very clearly resting in two different positions. | |
| Sep 2, 2019 at 8:36 | comment | added | 比尔盖子 | You're right. It's completely irrelevant. I originally thought that a double-throw switch allows one to use the classic SR latch debouncer, but after checking the schmatics of various PDP-8 front panels, I found the momentary toggle switches on some models were single-throw. Also, packaged gates, either latches, Schmitt triggers or single-shots were used in all debouncing circuits, there was really no advantage of using a double-throw, so I am incorrect. | |
| Sep 2, 2019 at 8:08 | answer | added | Raffzahn | timeline score: 5 | |
| Sep 2, 2019 at 7:38 | comment | added | cjs | @比尔盖子 That seems very odd to me, because I don't see what the difference would be between the two poles of an NO pushbutton and the two poles of an OFF-(ON) toggle switch. Wouldn't you debounce either in the same way, using one of any number of methods? (FWIW, the Altair 8800 used 1/2 74x123, which I guess included an "RC" circuit because that chip wants an external cap and resistor to set the timing constant for the pulse length.) | |
| Sep 2, 2019 at 7:34 | comment | added | 比尔盖子 | Electronically speaking, switch denouncing may be easier to implement for momentary toggle switches (gates) than a pushbutton (RC circuit). But I'm not sure if it's really a contributing factor to the front panel design. I'll check some schematics and report back... | |
| Sep 2, 2019 at 4:07 | history | asked | cjs | CC BY-SA 4.0 |