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Why did early computer designers eschew integers?
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Several early computer designs regarded a 'word' as representing not an integer, with the bits having values 2^0, 2^1, 2^2, ..., but as representing a fixed-point fraction 2^-1, 2^-2, 2^-3, ...
(For the sake of simplicity in this question I'm ignoring the existence of the sign bit and talk only in terms of positive numbers)
Some examples of this convention are EDVAC, EDSAC, and the IAS machine.
Why was this? To me, having dealt with since the 1970s with machines that have "integers" at base, this seems a strange way to look at it.
Does it affect the machine operation in any way? Addition and subtraction are the same regardless of what you think the bits mean, but I suppose that for multiplication of two N-bit words giving an N-bit result, the choice of which N bits to keep depends on your interpretation. (Integer: you want the "right hand word"; fixed-point fraction, you want the "left hand word").
history
asked 1 hour ago
another-daveanother-dave
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add a comment |
Several early computer designs regarded a 'word' as representing not an integer, with the bits having values 2^0, 2^1, 2^2, ..., but as representing a fixed-point fraction 2^-1, 2^-2, 2^-3, ...
(For the sake of simplicity in this question I'm ignoring the existence of the sign bit and talk only in terms of positive numbers)
Some examples of this convention are EDVAC, EDSAC, and the IAS machine.
Why was this? To me, having dealt with since the 1970s with machines that have "integers" at base, this seems a strange way to look at it.
Does it affect the machine operation in any way? Addition and subtraction are the same regardless of what you think the bits mean, but I suppose that for multiplication of two N-bit words giving an N-bit result, the choice of which N bits to keep depends on your interpretation. (Integer: you want the "right hand word"; fixed-point fraction, you want the "left hand word").
history
asked 1 hour ago
another-daveanother-dave
1,172112
1
Very early on, it was likely that computers were not considered to be general purpose machines. So if the main task for which a computer was designed involved doing calculations with flractional numbers, prioritizing them over integers would make sense. It seems likely that computers designed for business programs would be more tuned to integers, because money (in the USA) can be treated as pennies, and very little would need to be fractional.
– RichF
1 hour ago
add a comment |
Several early computer designs regarded a 'word' as representing not an integer, with the bits having values 2^0, 2^1, 2^2, ..., but as representing a fixed-point fraction 2^-1, 2^-2, 2^-3, ...
(For the sake of simplicity in this question I'm ignoring the existence of the sign bit and talk only in terms of positive numbers)
Some examples of this convention are EDVAC, EDSAC, and the IAS machine.
Why was this? To me, having dealt with since the 1970s with machines that have "integers" at base, this seems a strange way to look at it.
Does it affect the machine operation in any way? Addition and subtraction are the same regardless of what you think the bits mean, but I suppose that for multiplication of two N-bit words giving an N-bit result, the choice of which N bits to keep depends on your interpretation. (Integer: you want the "right hand word"; fixed-point fraction, you want the "left hand word").
history
asked 1 hour ago
another-daveanother-dave
1,172112
Several early computer designs regarded a 'word' as representing not an integer, with the bits having values 2^0, 2^1, 2^2, ..., but as representing a fixed-point fraction 2^-1, 2^-2, 2^-3, ...
(For the sake of simplicity in this question I'm ignoring the existence of the sign bit and talk only in terms of positive numbers)
Some examples of this convention are EDVAC, EDSAC, and the IAS machine.
Why was this? To me, having dealt with since the 1970s with machines that have "integers" at base, this seems a strange way to look at it.
Does it affect the machine operation in any way? Addition and subtraction are the same regardless of what you think the bits mean, but I suppose that for multiplication of two N-bit words giving an N-bit result, the choice of which N bits to keep depends on your interpretation. (Integer: you want the "right hand word"; fixed-point fraction, you want the "left hand word").
history
history
asked 1 hour ago
another-daveanother-dave
1,172112
asked 1 hour ago
another-daveanother-dave
1,172112
asked 1 hour ago
another-daveanother-dave
1,172112
asked 1 hour ago
another-daveanother-dave
1,172112
asked 1 hour ago
another-daveanother-dave
1,172112
1,172112
1
Very early on, it was likely that computers were not considered to be general purpose machines. So if the main task for which a computer was designed involved doing calculations with flractional numbers, prioritizing them over integers would make sense. It seems likely that computers designed for business programs would be more tuned to integers, because money (in the USA) can be treated as pennies, and very little would need to be fractional.
– RichF
1 hour ago
add a comment |
1
Very early on, it was likely that computers were not considered to be general purpose machines. So if the main task for which a computer was designed involved doing calculations with flractional numbers, prioritizing them over integers would make sense. It seems likely that computers designed for business programs would be more tuned to integers, because money (in the USA) can be treated as pennies, and very little would need to be fractional.
– RichF
1 hour ago
1
1
Very early on, it was likely that computers were not considered to be general purpose machines. So if the main task for which a computer was designed involved doing calculations with flractional numbers, prioritizing them over integers would make sense. It seems likely that computers designed for business programs would be more tuned to integers, because money (in the USA) can be treated as pennies, and very little would need to be fractional.
– RichF
1 hour ago
Very early on, it was likely that computers were not considered to be general purpose machines. So if the main task for which a computer was designed involved doing calculations with flractional numbers, prioritizing them over integers would make sense. It seems likely that computers designed for business programs would be more tuned to integers, because money (in the USA) can be treated as pennies, and very little would need to be fractional.
– RichF
1 hour ago
add a comment |
1 Answer
1
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I'd think that it was mostly down to the preferences of John von Neumann at the time. He was a strong advocate of fixed point representations, and early computers were designed with long words to accommodate a large range of numbers that way. You certainly don't need 30-40 bits to cover the most useful integers, but that many were needed if you wanted plenty of digits before and after the decimal point.
By the 1970s though, the costs of integration were such that much smaller word sizes made sense. Minicomputers were commonly 16 bit architectures, and micros 8 bits or sometimes even 4. At that point you needed all the integers you can get, plus floating point had largely replaced fixed point for when you needed decimals.
Nowadays we'd think nothing of using 64 bit integers, of course, but it's a heck of a lot easier to integrate the number of logic gates required for that than it would have been back when they all had to be made out of fragile and expensive vacuum tubes.
answered 46 mins ago
Matthew BarberMatthew Barber
1411
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I'd think that it was mostly down to the preferences of John von Neumann at the time. He was a strong advocate of fixed point representations, and early computers were designed with long words to accommodate a large range of numbers that way. You certainly don't need 30-40 bits to cover the most useful integers, but that many were needed if you wanted plenty of digits before and after the decimal point.
By the 1970s though, the costs of integration were such that much smaller word sizes made sense. Minicomputers were commonly 16 bit architectures, and micros 8 bits or sometimes even 4. At that point you needed all the integers you can get, plus floating point had largely replaced fixed point for when you needed decimals.
Nowadays we'd think nothing of using 64 bit integers, of course, but it's a heck of a lot easier to integrate the number of logic gates required for that than it would have been back when they all had to be made out of fragile and expensive vacuum tubes.
answered 46 mins ago
Matthew BarberMatthew Barber
1411
New contributor
Matthew Barber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I'd think that it was mostly down to the preferences of John von Neumann at the time. He was a strong advocate of fixed point representations, and early computers were designed with long words to accommodate a large range of numbers that way. You certainly don't need 30-40 bits to cover the most useful integers, but that many were needed if you wanted plenty of digits before and after the decimal point.
By the 1970s though, the costs of integration were such that much smaller word sizes made sense. Minicomputers were commonly 16 bit architectures, and micros 8 bits or sometimes even 4. At that point you needed all the integers you can get, plus floating point had largely replaced fixed point for when you needed decimals.
Nowadays we'd think nothing of using 64 bit integers, of course, but it's a heck of a lot easier to integrate the number of logic gates required for that than it would have been back when they all had to be made out of fragile and expensive vacuum tubes.
answered 46 mins ago
Matthew BarberMatthew Barber
1411
New contributor
Matthew Barber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I'd think that it was mostly down to the preferences of John von Neumann at the time. He was a strong advocate of fixed point representations, and early computers were designed with long words to accommodate a large range of numbers that way. You certainly don't need 30-40 bits to cover the most useful integers, but that many were needed if you wanted plenty of digits before and after the decimal point.
By the 1970s though, the costs of integration were such that much smaller word sizes made sense. Minicomputers were commonly 16 bit architectures, and micros 8 bits or sometimes even 4. At that point you needed all the integers you can get, plus floating point had largely replaced fixed point for when you needed decimals.
Nowadays we'd think nothing of using 64 bit integers, of course, but it's a heck of a lot easier to integrate the number of logic gates required for that than it would have been back when they all had to be made out of fragile and expensive vacuum tubes.
answered 46 mins ago
Matthew BarberMatthew Barber
1411
New contributor
Matthew Barber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'd think that it was mostly down to the preferences of John von Neumann at the time. He was a strong advocate of fixed point representations, and early computers were designed with long words to accommodate a large range of numbers that way. You certainly don't need 30-40 bits to cover the most useful integers, but that many were needed if you wanted plenty of digits before and after the decimal point.
By the 1970s though, the costs of integration were such that much smaller word sizes made sense. Minicomputers were commonly 16 bit architectures, and micros 8 bits or sometimes even 4. At that point you needed all the integers you can get, plus floating point had largely replaced fixed point for when you needed decimals.
Nowadays we'd think nothing of using 64 bit integers, of course, but it's a heck of a lot easier to integrate the number of logic gates required for that than it would have been back when they all had to be made out of fragile and expensive vacuum tubes.
answered 46 mins ago
Matthew BarberMatthew Barber
1411
New contributor
Matthew Barber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 46 mins ago
Matthew BarberMatthew Barber
1411
New contributor
Matthew Barber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 46 mins ago
Matthew BarberMatthew Barber
1411
answered 46 mins ago
Matthew BarberMatthew Barber
1411
1411
New contributor
Matthew Barber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Matthew Barber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Matthew Barber is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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Very early on, it was likely that computers were not considered to be general purpose machines. So if the main task for which a computer was designed involved doing calculations with flractional numbers, prioritizing them over integers would make sense. It seems likely that computers designed for business programs would be more tuned to integers, because money (in the USA) can be treated as pennies, and very little would need to be fractional.
– RichF
1 hour ago