Difference between revisions of "Machine Unit"

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THE ANALOG THING's '''machine unit''' is the voltage interval in which the device represents values. This interval is -10V to +10V. THAT users are expected to scale their programs to fit into the interval <code>[-1,+1]</code>, which THAT represents in its -10V to +10V machine unit.
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THAT can compute values in the range from -1 to 1. In most applications, this requires users to ''scale'' programs such that their values to fit into this range. THAT represents this unit range -1 to 1 with voltages ranging from -10V to 10V. This voltage range is called the '''machine unit'''.
  
To understand the need for these scale conversions, consider that users want to model values at any scale while THAT is limited to its modest physical boundaries. Modeling the dynamics of the global human population (currently around 7.9 Billion) should obviously not require 7.9 Billion Volts. The population value needs to be scaled. As a convention, analog computer models are scaled to the model unit <code>[-1,+1]</code>. The global population might, for example, be represented as 0.79. In its machine unit, THAT would then represent this value as 7.9V.  
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To understand the need for these scale conversions, consider that users want to model values at any scale while THAT is limited to its modest physical boundaries. Modeling the dynamics of the global human population (currently around 7.9 Billion) should obviously not require 7.9 Billion volts. The population value needs to be scaled to fit into the unit range -1 to 1 and into the machine unit -10v to 10V. The global population might, for example, be represented as 0.79, i.e., 7.9V.  
  
Good model scaling results in programs that use as much of the machine unit as possible ​without exceeding it. You understand the reasons for this if you understand that weighing cooking ingredients on scales intended for trucks or weighing a truck on a kitchen scale would not give very useful results.
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Good scaling results in programs that use large portions of the machine unit ​​without exceeding it. Using only small portions of the machine unit reduces computational precision - much in the way in which weighing small amounts of cooking ingredients on a scale intended for people would not be very precise. Exceeding the machine unit leads to meaningless results - much in the way in which weighing a person on a kitchen scale would.
  
Using the -10V to +10V range as the machine unit is an engineering choice and a convention. It happens to be a very good choice because it allows for easy conversions in the decimal number system, it can be handled very precisely using affordable electronic components, and it is perfectly safe for humans.
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The use of the -10V to +10V range as the machine unit is an engineering choice. This range happens to be a very good choice because it allows for easy conversions in the decimal number system, it can be handled very precisely using affordable electronic components, and it is safe for humans.
  
When any value in a program exceeds the machine unit, the red <code>OL</code> (overload) LED lights up. This is not dangerous for the device. However, in this condition, THAT will likely "clip" any excess voltages, and the values in question will not be computationally correct.
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When any value in a program exceeds the machine unit, the red <code>OL</code> (overload) LED lights up. This is not dangerous for the device. However, in this condition, THAT will likely "clip" voltages exceeding the machine unit such that the affected values will no longer be computationally correct.
  
 
Output signals available via the RCA (or "chinch") jacks on the device's backside are not in the machine unit. Instead, they are attenuated to smaller audio signal levels to conveniently be read into software [[oscilloscope]]s via sound card interfaces.
 
Output signals available via the RCA (or "chinch") jacks on the device's backside are not in the machine unit. Instead, they are attenuated to smaller audio signal levels to conveniently be read into software [[oscilloscope]]s via sound card interfaces.

Latest revision as of 05:22, 30 August 2021

THAT can compute values in the range from -1 to 1. In most applications, this requires users to scale programs such that their values to fit into this range. THAT represents this unit range -1 to 1 with voltages ranging from -10V to 10V. This voltage range is called the machine unit.

To understand the need for these scale conversions, consider that users want to model values at any scale while THAT is limited to its modest physical boundaries. Modeling the dynamics of the global human population (currently around 7.9 Billion) should obviously not require 7.9 Billion volts. The population value needs to be scaled to fit into the unit range -1 to 1 and into the machine unit -10v to 10V. The global population might, for example, be represented as 0.79, i.e., 7.9V.

Good scaling results in programs that use large portions of the machine unit ​​without exceeding it. Using only small portions of the machine unit reduces computational precision - much in the way in which weighing small amounts of cooking ingredients on a scale intended for people would not be very precise. Exceeding the machine unit leads to meaningless results - much in the way in which weighing a person on a kitchen scale would.

The use of the -10V to +10V range as the machine unit is an engineering choice. This range happens to be a very good choice because it allows for easy conversions in the decimal number system, it can be handled very precisely using affordable electronic components, and it is safe for humans.

When any value in a program exceeds the machine unit, the red OL (overload) LED lights up. This is not dangerous for the device. However, in this condition, THAT will likely "clip" voltages exceeding the machine unit such that the affected values will no longer be computationally correct.

Output signals available via the RCA (or "chinch") jacks on the device's backside are not in the machine unit. Instead, they are attenuated to smaller audio signal levels to conveniently be read into software oscilloscopes via sound card interfaces.