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How does a computer alarm clock application work [on hold]

How does rebooting a computer work?Computer Alarm Software?MacOS X alarm clock with radioHow does 'strace' work?Does Android or Java use more power since it's running on a virtual machine?How do you enable speaker output while headphones are on for SELECT programs?Need assistance SECURELY accessing home network from Android devicePrevent/Configure Androids unloading/suspending of apps not 'on top'Using computer (VLC) as an alarm clockCan't stop alarm clock on Windows Mobile 10

0

How does an alarm clock application actually work, for example for Android phones or even for a general Linux system?

When we set an alarm, the computer knows the alarm time and the current time.

Does it then compare the times in software every single second or minute that passes to see if the current time matches the alarm time? I'd guess this may be too much overhead tho?

Could it be implemented in hardware such that logic gates for example produce a high value when two inputs (alarm and current time) are the same, and can then inform the application to sound the alarm. I feel however that this way would be used in real embedded systems and might be too "low-level" for Android / IoS applications?

linux android process ios alarm-clock

share|improve this question

edited yesterday

Engineer999

asked yesterday

Engineer999Engineer999

1095

put on hold as off-topic by DavidPostill♦ yesterday

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question is not about computer hardware or software, within the scope defined in the help center." – DavidPostill

If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  “I'd guess this may be too much overhead tho?” How do cheap digital watches work? Do they need cooling systems?
  
  – JakeGould
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @JakeGould Polling every second for example and comparing times. What if we then have 100s of alarms set? I'm talking about a phone application and not exactly a watch.
  
  – Engineer999
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  There are a variety of ways in which this functionality could be implemented... it all depends on what level of precision and reliability you require. Typically, the application would request an interrupt / signal / unblock at a point in time... possibly calculated (i.e: "now + 300 seconds"), or possibly an absolute time (i.e: "19:13 on <date>"... but in another format). The requested point in time would be the next closes alarm time.
  
  – Attie
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I don't know about iOS, but Android certainly has the ability to register an alarm with the system... the application would then be awake and running at this time (something you can't necessarily guarantee otherwise)
  
  – Attie
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Attie Now what happens if the alarm is set and we adjust the current time and the alarm is due to go off in the next 60 seconds?
  
  – Engineer999
  yesterday
  

  
  
  
  

 | 
show 4 more comments

0

How does an alarm clock application actually work, for example for Android phones or even for a general Linux system?

When we set an alarm, the computer knows the alarm time and the current time.

Does it then compare the times in software every single second or minute that passes to see if the current time matches the alarm time? I'd guess this may be too much overhead tho?

Could it be implemented in hardware such that logic gates for example produce a high value when two inputs (alarm and current time) are the same, and can then inform the application to sound the alarm. I feel however that this way would be used in real embedded systems and might be too "low-level" for Android / IoS applications?

linux android process ios alarm-clock

share|improve this question

edited yesterday

Engineer999

asked yesterday

Engineer999Engineer999

1095

put on hold as off-topic by DavidPostill♦ yesterday

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question is not about computer hardware or software, within the scope defined in the help center." – DavidPostill

If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  “I'd guess this may be too much overhead tho?” How do cheap digital watches work? Do they need cooling systems?
  
  – JakeGould
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @JakeGould Polling every second for example and comparing times. What if we then have 100s of alarms set? I'm talking about a phone application and not exactly a watch.
  
  – Engineer999
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  There are a variety of ways in which this functionality could be implemented... it all depends on what level of precision and reliability you require. Typically, the application would request an interrupt / signal / unblock at a point in time... possibly calculated (i.e: "now + 300 seconds"), or possibly an absolute time (i.e: "19:13 on <date>"... but in another format). The requested point in time would be the next closes alarm time.
  
  – Attie
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I don't know about iOS, but Android certainly has the ability to register an alarm with the system... the application would then be awake and running at this time (something you can't necessarily guarantee otherwise)
  
  – Attie
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Attie Now what happens if the alarm is set and we adjust the current time and the alarm is due to go off in the next 60 seconds?
  
  – Engineer999
  yesterday
  

  
  
  
  

 | 
show 4 more comments

How does an alarm clock application actually work, for example for Android phones or even for a general Linux system?

When we set an alarm, the computer knows the alarm time and the current time.

Does it then compare the times in software every single second or minute that passes to see if the current time matches the alarm time? I'd guess this may be too much overhead tho?

Could it be implemented in hardware such that logic gates for example produce a high value when two inputs (alarm and current time) are the same, and can then inform the application to sound the alarm. I feel however that this way would be used in real embedded systems and might be too "low-level" for Android / IoS applications?

linux android process ios alarm-clock

share|improve this question

edited yesterday

Engineer999

asked yesterday

Engineer999Engineer999

1095

share|improve this question

edited yesterday

Engineer999

asked yesterday

Engineer999Engineer999

1095

share|improve this question

edited yesterday

Engineer999

asked yesterday

Engineer999Engineer999

1095

asked yesterday

Engineer999Engineer999

1095

asked yesterday

Engineer999Engineer999

1095