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Why does PAUSE key have a long make code and no break code?
Troubleshooting and reparing an Atari 800XL with a single key not workingWhy are the | and ¦ keys labelled the wrong way around?Why did F1 become the Help Key?Who established the original F1 desktop BIOS key and why did laptops use a different key?Why did the C64 have ← and ↑ as dedicated keys?
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On IBM keyboards, scan code sets 1 and 2 have a long make code and lack a break code for the Pause/Break key. Moreover, when Ctrl is pressed, the make code is different, although break code still doesn't exist.*
In scan code set 3 there does appear the break code, but this set isn't used much.
What was the reason for Pause/Break to be treated so specially to not even have a break code?
*See detailed tables in e.g. this spec for EM83053DH keyboard encoder. I've checked experimentally that description for Pause/Break is correct at least with set 2 active.
keyboards
asked 8 hours ago
RuslanRuslan
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add a comment |
On IBM keyboards, scan code sets 1 and 2 have a long make code and lack a break code for the Pause/Break key. Moreover, when Ctrl is pressed, the make code is different, although break code still doesn't exist.*
In scan code set 3 there does appear the break code, but this set isn't used much.
What was the reason for Pause/Break to be treated so specially to not even have a break code?
*See detailed tables in e.g. this spec for EM83053DH keyboard encoder. I've checked experimentally that description for Pause/Break is correct at least with set 2 active.
keyboards
asked 8 hours ago
RuslanRuslan
6155 silver badges13 bronze badges
add a comment |
On IBM keyboards, scan code sets 1 and 2 have a long make code and lack a break code for the Pause/Break key. Moreover, when Ctrl is pressed, the make code is different, although break code still doesn't exist.*
In scan code set 3 there does appear the break code, but this set isn't used much.
What was the reason for Pause/Break to be treated so specially to not even have a break code?
*See detailed tables in e.g. this spec for EM83053DH keyboard encoder. I've checked experimentally that description for Pause/Break is correct at least with set 2 active.
keyboards
asked 8 hours ago
RuslanRuslan
6155 silver badges13 bronze badges
On IBM keyboards, scan code sets 1 and 2 have a long make code and lack a break code for the Pause/Break key. Moreover, when Ctrl is pressed, the make code is different, although break code still doesn't exist.*
In scan code set 3 there does appear the break code, but this set isn't used much.
What was the reason for Pause/Break to be treated so specially to not even have a break code?
*See detailed tables in e.g. this spec for EM83053DH keyboard encoder. I've checked experimentally that description for Pause/Break is correct at least with set 2 active.
keyboards
keyboards
asked 8 hours ago
RuslanRuslan
6155 silver badges13 bronze badges
asked 8 hours ago
RuslanRuslan
6155 silver badges13 bronze badges
asked 8 hours ago
RuslanRuslan
6155 silver badges13 bronze badges
asked 8 hours ago
RuslanRuslan
6155 silver badges13 bronze badges
asked 8 hours ago
RuslanRuslan
6155 silver badges13 bronze badges
6155 silver badges13 bronze badges
add a comment |
add a comment |
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In scancode set 2, the "break" scancodes consist of the "make" scancodes prefixed by F0. This is consistent across nearly all the keys. Some keys include a modifier prefix in the Ex range as well, and this is repeated in the "break" sequence. Additionally some keys behave as if two keys are pressed at once, and thus include multiple F0 codes to ensure that both virtual keys are seen as released by the host PC.
The "make" scancode for the Pause/Break key, however, is E1 14 77 E1 F0 14 F0 77. Examining this closely, this is actually a combined "make" then "break" sequence for a composite scancode: E1 14 77, then E1 F0 14 F0 77. So when you press that key, it is seen as pressed only momentarily by the host PC, even if you hold it down.
Yes, this is a hopeless mess. I think it resulted from the gradual evolution of the PC keyboard through its early history. The USB-HID scancode set is completely different, this obviously being seen as an opportunity to discard the cruft.
answered 7 hours ago
ChromatixChromatix
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1 Answer
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In scancode set 2, the "break" scancodes consist of the "make" scancodes prefixed by F0. This is consistent across nearly all the keys. Some keys include a modifier prefix in the Ex range as well, and this is repeated in the "break" sequence. Additionally some keys behave as if two keys are pressed at once, and thus include multiple F0 codes to ensure that both virtual keys are seen as released by the host PC.
The "make" scancode for the Pause/Break key, however, is E1 14 77 E1 F0 14 F0 77. Examining this closely, this is actually a combined "make" then "break" sequence for a composite scancode: E1 14 77, then E1 F0 14 F0 77. So when you press that key, it is seen as pressed only momentarily by the host PC, even if you hold it down.
Yes, this is a hopeless mess. I think it resulted from the gradual evolution of the PC keyboard through its early history. The USB-HID scancode set is completely different, this obviously being seen as an opportunity to discard the cruft.
answered 7 hours ago
ChromatixChromatix
1,4309 silver badges8 bronze badges
add a comment |
In scancode set 2, the "break" scancodes consist of the "make" scancodes prefixed by F0. This is consistent across nearly all the keys. Some keys include a modifier prefix in the Ex range as well, and this is repeated in the "break" sequence. Additionally some keys behave as if two keys are pressed at once, and thus include multiple F0 codes to ensure that both virtual keys are seen as released by the host PC.
The "make" scancode for the Pause/Break key, however, is E1 14 77 E1 F0 14 F0 77. Examining this closely, this is actually a combined "make" then "break" sequence for a composite scancode: E1 14 77, then E1 F0 14 F0 77. So when you press that key, it is seen as pressed only momentarily by the host PC, even if you hold it down.
Yes, this is a hopeless mess. I think it resulted from the gradual evolution of the PC keyboard through its early history. The USB-HID scancode set is completely different, this obviously being seen as an opportunity to discard the cruft.
answered 7 hours ago
ChromatixChromatix
1,4309 silver badges8 bronze badges
add a comment |
In scancode set 2, the "break" scancodes consist of the "make" scancodes prefixed by F0. This is consistent across nearly all the keys. Some keys include a modifier prefix in the Ex range as well, and this is repeated in the "break" sequence. Additionally some keys behave as if two keys are pressed at once, and thus include multiple F0 codes to ensure that both virtual keys are seen as released by the host PC.
The "make" scancode for the Pause/Break key, however, is E1 14 77 E1 F0 14 F0 77. Examining this closely, this is actually a combined "make" then "break" sequence for a composite scancode: E1 14 77, then E1 F0 14 F0 77. So when you press that key, it is seen as pressed only momentarily by the host PC, even if you hold it down.
Yes, this is a hopeless mess. I think it resulted from the gradual evolution of the PC keyboard through its early history. The USB-HID scancode set is completely different, this obviously being seen as an opportunity to discard the cruft.
answered 7 hours ago
ChromatixChromatix
1,4309 silver badges8 bronze badges
In scancode set 2, the "break" scancodes consist of the "make" scancodes prefixed by F0. This is consistent across nearly all the keys. Some keys include a modifier prefix in the Ex range as well, and this is repeated in the "break" sequence. Additionally some keys behave as if two keys are pressed at once, and thus include multiple F0 codes to ensure that both virtual keys are seen as released by the host PC.
The "make" scancode for the Pause/Break key, however, is E1 14 77 E1 F0 14 F0 77. Examining this closely, this is actually a combined "make" then "break" sequence for a composite scancode: E1 14 77, then E1 F0 14 F0 77. So when you press that key, it is seen as pressed only momentarily by the host PC, even if you hold it down.
Yes, this is a hopeless mess. I think it resulted from the gradual evolution of the PC keyboard through its early history. The USB-HID scancode set is completely different, this obviously being seen as an opportunity to discard the cruft.
answered 7 hours ago
ChromatixChromatix
1,4309 silver badges8 bronze badges
answered 7 hours ago
ChromatixChromatix
1,4309 silver badges8 bronze badges
answered 7 hours ago
ChromatixChromatix
1,4309 silver badges8 bronze badges
answered 7 hours ago
ChromatixChromatix
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