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Why wasn't EBCDIC designed with contiguous alphanumeric characters?
Why wasn't ASCII designed with a contiguous alphanumeric character order?Can I use my IBM P/N 93F0502 (circa 1992) monitor in a dual monitor setup with my modern Mac Mini or Thinkpad?Why would a CD-ROM in an MS-DOS 6.22 system not allow file access?What's the deal with System/360's “USASCII” mode?How to connect c3270 terminal with hercules emulator?Why does an instruction include the address of the next instruction on the IBM 650?Why are the symbols on the number keys of PC & Mac keyboards different to ASCII keyboards?What characters which were in use at the time were excluded from ASCII?Desk computer with embedded CRT, 8" floppyWhy wasn't ASCII designed with a contiguous alphanumeric character order?
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
Inspired by this question on ASCII, I have wondered similar things about EBCDIC.
At work we have an EBCDIC file that gets sent to a mainframe (I presume an IBM one) and to view it on my laptop I needed to run a command to convert it. dd if=blah.ebcdic conv=ascii > blah.txt Before I found that command I took a peek at the code page to see if I could whip something up myself.
Like ASCII you can shift a bit to get from lowercase to uppercase (0x8_ to 0xc_ is one bit different). However, the cases are not contiguous themselves. The low bits 0x_a to 0x_f are skipped. Is there a reason?
Also like ASCII, the numbers' low bits match the number they represent.
ibm ascii ebcdic
edited 5 hours ago
RonJohn
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asked 8 hours ago
Captain ManCaptain Man
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Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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add a comment |
Inspired by this question on ASCII, I have wondered similar things about EBCDIC.
At work we have an EBCDIC file that gets sent to a mainframe (I presume an IBM one) and to view it on my laptop I needed to run a command to convert it. dd if=blah.ebcdic conv=ascii > blah.txt Before I found that command I took a peek at the code page to see if I could whip something up myself.
Like ASCII you can shift a bit to get from lowercase to uppercase (0x8_ to 0xc_ is one bit different). However, the cases are not contiguous themselves. The low bits 0x_a to 0x_f are skipped. Is there a reason?
Also like ASCII, the numbers' low bits match the number they represent.
ibm ascii ebcdic
edited 5 hours ago
RonJohn
2601 silver badge7 bronze badges
asked 8 hours ago
Captain ManCaptain Man
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
See en.wikipedia.org/wiki/EBCDIC for a start, and note the relationships with punched cards and not wanting holes too close to each other for structural integrity.
– Jon Custer
7 hours ago
@JonCuster thanks for the insight, can you post the relation with punch cards as an answer so I can give it an upvote? If you would rather not I can post it myself, I just don't want you to feel like I'm "stealing" it.
– Captain Man
6 hours ago
feel free to steal! It has been a long time since I used punch cards (or dropped them on the floor).
– Jon Custer
6 hours ago
I'm not convinced by logic about avoiding card damage, for two reasons. One is that you often get long runs of holes in the top three rows from alphabetic data. The other is that IBM also used "column binary" format cards where the 24 positions in two rows represented 3 8-bit bytes. Storing binary data (e.g. executable file images) in that format, about 50% of the holes on every card were punched, and that never gave any problems. (We used to ship executable code in column binary format to customers who didn't have any compatible mag tape drives, and it never gave us any transmission errors).
– alephzero
5 hours ago
Radix-sorting cards that contain nothing but letters, numbers, and blanks requires two passes per character position. The first pass sorts cards into one of ten bins based upon the bottom nine rows, and the second sorts them into one of four bins based on the top three. Using more complicated hole patterns would necessitate the use of more passes or more complicated sorting apparatus.
– supercat
5 hours ago
add a comment |
Inspired by this question on ASCII, I have wondered similar things about EBCDIC.
At work we have an EBCDIC file that gets sent to a mainframe (I presume an IBM one) and to view it on my laptop I needed to run a command to convert it. dd if=blah.ebcdic conv=ascii > blah.txt Before I found that command I took a peek at the code page to see if I could whip something up myself.
Like ASCII you can shift a bit to get from lowercase to uppercase (0x8_ to 0xc_ is one bit different). However, the cases are not contiguous themselves. The low bits 0x_a to 0x_f are skipped. Is there a reason?
Also like ASCII, the numbers' low bits match the number they represent.
ibm ascii ebcdic
edited 5 hours ago
RonJohn
2601 silver badge7 bronze badges
asked 8 hours ago
Captain ManCaptain Man
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Inspired by this question on ASCII, I have wondered similar things about EBCDIC.
At work we have an EBCDIC file that gets sent to a mainframe (I presume an IBM one) and to view it on my laptop I needed to run a command to convert it. dd if=blah.ebcdic conv=ascii > blah.txt Before I found that command I took a peek at the code page to see if I could whip something up myself.
Like ASCII you can shift a bit to get from lowercase to uppercase (0x8_ to 0xc_ is one bit different). However, the cases are not contiguous themselves. The low bits 0x_a to 0x_f are skipped. Is there a reason?
Also like ASCII, the numbers' low bits match the number they represent.
ibm ascii ebcdic
ibm ascii ebcdic
edited 5 hours ago
RonJohn
2601 silver badge7 bronze badges
asked 8 hours ago
Captain ManCaptain Man
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 5 hours ago
RonJohn
2601 silver badge7 bronze badges
asked 8 hours ago
Captain ManCaptain Man
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Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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edited 5 hours ago
RonJohn
2601 silver badge7 bronze badges
edited 5 hours ago
RonJohn
2601 silver badge7 bronze badges
edited 5 hours ago
RonJohn
2601 silver badge7 bronze badges
2601 silver badge7 bronze badges
asked 8 hours ago
Captain ManCaptain Man
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
Captain ManCaptain Man
1266 bronze badges
asked 8 hours ago
Captain ManCaptain Man
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1266 bronze badges
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New contributor
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Check out our Code of Conduct.
1
See en.wikipedia.org/wiki/EBCDIC for a start, and note the relationships with punched cards and not wanting holes too close to each other for structural integrity.
– Jon Custer
7 hours ago
@JonCuster thanks for the insight, can you post the relation with punch cards as an answer so I can give it an upvote? If you would rather not I can post it myself, I just don't want you to feel like I'm "stealing" it.
– Captain Man
6 hours ago
feel free to steal! It has been a long time since I used punch cards (or dropped them on the floor).
– Jon Custer
6 hours ago
I'm not convinced by logic about avoiding card damage, for two reasons. One is that you often get long runs of holes in the top three rows from alphabetic data. The other is that IBM also used "column binary" format cards where the 24 positions in two rows represented 3 8-bit bytes. Storing binary data (e.g. executable file images) in that format, about 50% of the holes on every card were punched, and that never gave any problems. (We used to ship executable code in column binary format to customers who didn't have any compatible mag tape drives, and it never gave us any transmission errors).
– alephzero
5 hours ago
Radix-sorting cards that contain nothing but letters, numbers, and blanks requires two passes per character position. The first pass sorts cards into one of ten bins based upon the bottom nine rows, and the second sorts them into one of four bins based on the top three. Using more complicated hole patterns would necessitate the use of more passes or more complicated sorting apparatus.
– supercat
5 hours ago
add a comment |
1
See en.wikipedia.org/wiki/EBCDIC for a start, and note the relationships with punched cards and not wanting holes too close to each other for structural integrity.
– Jon Custer
7 hours ago
@JonCuster thanks for the insight, can you post the relation with punch cards as an answer so I can give it an upvote? If you would rather not I can post it myself, I just don't want you to feel like I'm "stealing" it.
– Captain Man
6 hours ago
feel free to steal! It has been a long time since I used punch cards (or dropped them on the floor).
– Jon Custer
6 hours ago
I'm not convinced by logic about avoiding card damage, for two reasons. One is that you often get long runs of holes in the top three rows from alphabetic data. The other is that IBM also used "column binary" format cards where the 24 positions in two rows represented 3 8-bit bytes. Storing binary data (e.g. executable file images) in that format, about 50% of the holes on every card were punched, and that never gave any problems. (We used to ship executable code in column binary format to customers who didn't have any compatible mag tape drives, and it never gave us any transmission errors).
– alephzero
5 hours ago
Radix-sorting cards that contain nothing but letters, numbers, and blanks requires two passes per character position. The first pass sorts cards into one of ten bins based upon the bottom nine rows, and the second sorts them into one of four bins based on the top three. Using more complicated hole patterns would necessitate the use of more passes or more complicated sorting apparatus.
– supercat
5 hours ago
1
1
See en.wikipedia.org/wiki/EBCDIC for a start, and note the relationships with punched cards and not wanting holes too close to each other for structural integrity.
– Jon Custer
7 hours ago
See en.wikipedia.org/wiki/EBCDIC for a start, and note the relationships with punched cards and not wanting holes too close to each other for structural integrity.
– Jon Custer
7 hours ago
@JonCuster thanks for the insight, can you post the relation with punch cards as an answer so I can give it an upvote? If you would rather not I can post it myself, I just don't want you to feel like I'm "stealing" it.
– Captain Man
6 hours ago
@JonCuster thanks for the insight, can you post the relation with punch cards as an answer so I can give it an upvote? If you would rather not I can post it myself, I just don't want you to feel like I'm "stealing" it.
– Captain Man
6 hours ago
feel free to steal! It has been a long time since I used punch cards (or dropped them on the floor).
– Jon Custer
6 hours ago
feel free to steal! It has been a long time since I used punch cards (or dropped them on the floor).
– Jon Custer
6 hours ago
I'm not convinced by logic about avoiding card damage, for two reasons. One is that you often get long runs of holes in the top three rows from alphabetic data. The other is that IBM also used "column binary" format cards where the 24 positions in two rows represented 3 8-bit bytes. Storing binary data (e.g. executable file images) in that format, about 50% of the holes on every card were punched, and that never gave any problems. (We used to ship executable code in column binary format to customers who didn't have any compatible mag tape drives, and it never gave us any transmission errors).
– alephzero
5 hours ago
I'm not convinced by logic about avoiding card damage, for two reasons. One is that you often get long runs of holes in the top three rows from alphabetic data. The other is that IBM also used "column binary" format cards where the 24 positions in two rows represented 3 8-bit bytes. Storing binary data (e.g. executable file images) in that format, about 50% of the holes on every card were punched, and that never gave any problems. (We used to ship executable code in column binary format to customers who didn't have any compatible mag tape drives, and it never gave us any transmission errors).
– alephzero
5 hours ago
Radix-sorting cards that contain nothing but letters, numbers, and blanks requires two passes per character position. The first pass sorts cards into one of ten bins based upon the bottom nine rows, and the second sorts them into one of four bins based on the top three. Using more complicated hole patterns would necessitate the use of more passes or more complicated sorting apparatus.
– supercat
5 hours ago
Radix-sorting cards that contain nothing but letters, numbers, and blanks requires two passes per character position. The first pass sorts cards into one of ten bins based upon the bottom nine rows, and the second sorts them into one of four bins based on the top three. Using more complicated hole patterns would necessitate the use of more passes or more complicated sorting apparatus.
– supercat
5 hours ago
add a comment |
2 Answers
2
active
oldest
votes
The clue is in the name - BCD stands for "binary-coded decimal", where 4 bits are used to represent 1 decimal digit. EBCDIC is an extended version of BCDIC, and it shifts BCDIC alphanumerics, and inserts characters in some of the non-decimal positions. But there's a simple relationship to ease conversion of BCDIC to EBCDIC.
answered 7 hours ago
Toby SpeightToby Speight
3573 silver badges12 bronze badges
I suppose this begs the question whyBCDICencoding is not contiguous but as Jon Custer mentioned in a comment it has to do with punch cards and ensuring the holes are not too close together.
– Captain Man
7 hours ago
BCDIC has the same issue, "binary coded decimal" uses 4 bits to encode digits from 0-9, which means hex values a-f will generally not be used. The gaps where the a-f ranges fall will naturally lead to non-contiguous encodings.
– Ken Gober
6 hours ago
add a comment |
As pointed out by Jon Custer, part of the reason is due to the input at the time being punch cards. If holes were close together there was a risk of the card being unreadable or ripping.
In addition, this punch card from the Wikipedia article helps explain why both uppercase and lowercase end at 0x_9. The punch card only goes from 0 to 9. I don't know how A through F were entered, maybe different cards or multiple holes (or maybe Wikipedia is wrong and this is for BCDIC, not EBCDIC).
answered 6 hours ago
Captain ManCaptain Man
1266 bronze badges
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Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
A..F wasn't entered at all, as input was decimal. Mainframes where made to cranc out invoices, all decimal in dollars and cents (or whatever else was used to create debt). Maiking them binary was already an odd move creating a lot of fights between designers :))
– Raffzahn
3 hours ago
That card is a standard IBM punched card that uses 12 positions for encoding. Each of the decimal digits is represented by a hole in one of 10 positions. Each letter is represented by a hole in one of three extra positions and one of the digit positions. Other characters are represented by two or three holes in various combinations. BCDIC is a way of compressing the 12 bit code of the card into only 6 bits.
– JeremyP
1 hour ago
I'm not sure what you mean by "how were A through F encoded". They were encoded in exactly the same way as on that punched card. This is a character encoding, not a number encoding.
– JeremyP
1 hour ago
add a comment |
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2 Answers
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2 Answers
2
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The clue is in the name - BCD stands for "binary-coded decimal", where 4 bits are used to represent 1 decimal digit. EBCDIC is an extended version of BCDIC, and it shifts BCDIC alphanumerics, and inserts characters in some of the non-decimal positions. But there's a simple relationship to ease conversion of BCDIC to EBCDIC.
answered 7 hours ago
Toby SpeightToby Speight
3573 silver badges12 bronze badges
I suppose this begs the question whyBCDICencoding is not contiguous but as Jon Custer mentioned in a comment it has to do with punch cards and ensuring the holes are not too close together.
– Captain Man
7 hours ago
BCDIC has the same issue, "binary coded decimal" uses 4 bits to encode digits from 0-9, which means hex values a-f will generally not be used. The gaps where the a-f ranges fall will naturally lead to non-contiguous encodings.
– Ken Gober
6 hours ago
add a comment |
The clue is in the name - BCD stands for "binary-coded decimal", where 4 bits are used to represent 1 decimal digit. EBCDIC is an extended version of BCDIC, and it shifts BCDIC alphanumerics, and inserts characters in some of the non-decimal positions. But there's a simple relationship to ease conversion of BCDIC to EBCDIC.
answered 7 hours ago
Toby SpeightToby Speight
3573 silver badges12 bronze badges
I suppose this begs the question whyBCDICencoding is not contiguous but as Jon Custer mentioned in a comment it has to do with punch cards and ensuring the holes are not too close together.
– Captain Man
7 hours ago
BCDIC has the same issue, "binary coded decimal" uses 4 bits to encode digits from 0-9, which means hex values a-f will generally not be used. The gaps where the a-f ranges fall will naturally lead to non-contiguous encodings.
– Ken Gober
6 hours ago
add a comment |
The clue is in the name - BCD stands for "binary-coded decimal", where 4 bits are used to represent 1 decimal digit. EBCDIC is an extended version of BCDIC, and it shifts BCDIC alphanumerics, and inserts characters in some of the non-decimal positions. But there's a simple relationship to ease conversion of BCDIC to EBCDIC.
answered 7 hours ago
Toby SpeightToby Speight
3573 silver badges12 bronze badges
The clue is in the name - BCD stands for "binary-coded decimal", where 4 bits are used to represent 1 decimal digit. EBCDIC is an extended version of BCDIC, and it shifts BCDIC alphanumerics, and inserts characters in some of the non-decimal positions. But there's a simple relationship to ease conversion of BCDIC to EBCDIC.
answered 7 hours ago
Toby SpeightToby Speight
3573 silver badges12 bronze badges
answered 7 hours ago
Toby SpeightToby Speight
3573 silver badges12 bronze badges
answered 7 hours ago
Toby SpeightToby Speight
3573 silver badges12 bronze badges
answered 7 hours ago
Toby SpeightToby Speight
3573 silver badges12 bronze badges
3573 silver badges12 bronze badges
I suppose this begs the question whyBCDICencoding is not contiguous but as Jon Custer mentioned in a comment it has to do with punch cards and ensuring the holes are not too close together.
– Captain Man
7 hours ago
BCDIC has the same issue, "binary coded decimal" uses 4 bits to encode digits from 0-9, which means hex values a-f will generally not be used. The gaps where the a-f ranges fall will naturally lead to non-contiguous encodings.
– Ken Gober
6 hours ago
add a comment |
I suppose this begs the question whyBCDICencoding is not contiguous but as Jon Custer mentioned in a comment it has to do with punch cards and ensuring the holes are not too close together.
– Captain Man
7 hours ago
BCDIC has the same issue, "binary coded decimal" uses 4 bits to encode digits from 0-9, which means hex values a-f will generally not be used. The gaps where the a-f ranges fall will naturally lead to non-contiguous encodings.
– Ken Gober
6 hours ago
I suppose this begs the question why
BCDIC encoding is not contiguous but as Jon Custer mentioned in a comment it has to do with punch cards and ensuring the holes are not too close together.– Captain Man
7 hours ago
I suppose this begs the question why
BCDIC encoding is not contiguous but as Jon Custer mentioned in a comment it has to do with punch cards and ensuring the holes are not too close together.– Captain Man
7 hours ago
BCDIC has the same issue, "binary coded decimal" uses 4 bits to encode digits from 0-9, which means hex values a-f will generally not be used. The gaps where the a-f ranges fall will naturally lead to non-contiguous encodings.
– Ken Gober
6 hours ago
BCDIC has the same issue, "binary coded decimal" uses 4 bits to encode digits from 0-9, which means hex values a-f will generally not be used. The gaps where the a-f ranges fall will naturally lead to non-contiguous encodings.
– Ken Gober
6 hours ago
add a comment |
As pointed out by Jon Custer, part of the reason is due to the input at the time being punch cards. If holes were close together there was a risk of the card being unreadable or ripping.
In addition, this punch card from the Wikipedia article helps explain why both uppercase and lowercase end at 0x_9. The punch card only goes from 0 to 9. I don't know how A through F were entered, maybe different cards or multiple holes (or maybe Wikipedia is wrong and this is for BCDIC, not EBCDIC).
answered 6 hours ago
Captain ManCaptain Man
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
A..F wasn't entered at all, as input was decimal. Mainframes where made to cranc out invoices, all decimal in dollars and cents (or whatever else was used to create debt). Maiking them binary was already an odd move creating a lot of fights between designers :))
– Raffzahn
3 hours ago
That card is a standard IBM punched card that uses 12 positions for encoding. Each of the decimal digits is represented by a hole in one of 10 positions. Each letter is represented by a hole in one of three extra positions and one of the digit positions. Other characters are represented by two or three holes in various combinations. BCDIC is a way of compressing the 12 bit code of the card into only 6 bits.
– JeremyP
1 hour ago
I'm not sure what you mean by "how were A through F encoded". They were encoded in exactly the same way as on that punched card. This is a character encoding, not a number encoding.
– JeremyP
1 hour ago
add a comment |
As pointed out by Jon Custer, part of the reason is due to the input at the time being punch cards. If holes were close together there was a risk of the card being unreadable or ripping.
In addition, this punch card from the Wikipedia article helps explain why both uppercase and lowercase end at 0x_9. The punch card only goes from 0 to 9. I don't know how A through F were entered, maybe different cards or multiple holes (or maybe Wikipedia is wrong and this is for BCDIC, not EBCDIC).
answered 6 hours ago
Captain ManCaptain Man
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
A..F wasn't entered at all, as input was decimal. Mainframes where made to cranc out invoices, all decimal in dollars and cents (or whatever else was used to create debt). Maiking them binary was already an odd move creating a lot of fights between designers :))
– Raffzahn
3 hours ago
That card is a standard IBM punched card that uses 12 positions for encoding. Each of the decimal digits is represented by a hole in one of 10 positions. Each letter is represented by a hole in one of three extra positions and one of the digit positions. Other characters are represented by two or three holes in various combinations. BCDIC is a way of compressing the 12 bit code of the card into only 6 bits.
– JeremyP
1 hour ago
I'm not sure what you mean by "how were A through F encoded". They were encoded in exactly the same way as on that punched card. This is a character encoding, not a number encoding.
– JeremyP
1 hour ago
add a comment |
As pointed out by Jon Custer, part of the reason is due to the input at the time being punch cards. If holes were close together there was a risk of the card being unreadable or ripping.
In addition, this punch card from the Wikipedia article helps explain why both uppercase and lowercase end at 0x_9. The punch card only goes from 0 to 9. I don't know how A through F were entered, maybe different cards or multiple holes (or maybe Wikipedia is wrong and this is for BCDIC, not EBCDIC).
answered 6 hours ago
Captain ManCaptain Man
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
As pointed out by Jon Custer, part of the reason is due to the input at the time being punch cards. If holes were close together there was a risk of the card being unreadable or ripping.
In addition, this punch card from the Wikipedia article helps explain why both uppercase and lowercase end at 0x_9. The punch card only goes from 0 to 9. I don't know how A through F were entered, maybe different cards or multiple holes (or maybe Wikipedia is wrong and this is for BCDIC, not EBCDIC).
answered 6 hours ago
Captain ManCaptain Man
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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edited 6 hours ago
answered 6 hours ago
Captain ManCaptain Man
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New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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answered 6 hours ago
Captain ManCaptain Man
1266 bronze badges
answered 6 hours ago
Captain ManCaptain Man
1266 bronze badges
1266 bronze badges
New contributor
Captain Man is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
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A..F wasn't entered at all, as input was decimal. Mainframes where made to cranc out invoices, all decimal in dollars and cents (or whatever else was used to create debt). Maiking them binary was already an odd move creating a lot of fights between designers :))
– Raffzahn
3 hours ago
That card is a standard IBM punched card that uses 12 positions for encoding. Each of the decimal digits is represented by a hole in one of 10 positions. Each letter is represented by a hole in one of three extra positions and one of the digit positions. Other characters are represented by two or three holes in various combinations. BCDIC is a way of compressing the 12 bit code of the card into only 6 bits.
– JeremyP
1 hour ago
I'm not sure what you mean by "how were A through F encoded". They were encoded in exactly the same way as on that punched card. This is a character encoding, not a number encoding.
– JeremyP
1 hour ago
add a comment |
A..F wasn't entered at all, as input was decimal. Mainframes where made to cranc out invoices, all decimal in dollars and cents (or whatever else was used to create debt). Maiking them binary was already an odd move creating a lot of fights between designers :))
– Raffzahn
3 hours ago
That card is a standard IBM punched card that uses 12 positions for encoding. Each of the decimal digits is represented by a hole in one of 10 positions. Each letter is represented by a hole in one of three extra positions and one of the digit positions. Other characters are represented by two or three holes in various combinations. BCDIC is a way of compressing the 12 bit code of the card into only 6 bits.
– JeremyP
1 hour ago
I'm not sure what you mean by "how were A through F encoded". They were encoded in exactly the same way as on that punched card. This is a character encoding, not a number encoding.
– JeremyP
1 hour ago
A..F wasn't entered at all, as input was decimal. Mainframes where made to cranc out invoices, all decimal in dollars and cents (or whatever else was used to create debt). Maiking them binary was already an odd move creating a lot of fights between designers :))
– Raffzahn
3 hours ago
A..F wasn't entered at all, as input was decimal. Mainframes where made to cranc out invoices, all decimal in dollars and cents (or whatever else was used to create debt). Maiking them binary was already an odd move creating a lot of fights between designers :))
– Raffzahn
3 hours ago
That card is a standard IBM punched card that uses 12 positions for encoding. Each of the decimal digits is represented by a hole in one of 10 positions. Each letter is represented by a hole in one of three extra positions and one of the digit positions. Other characters are represented by two or three holes in various combinations. BCDIC is a way of compressing the 12 bit code of the card into only 6 bits.
– JeremyP
1 hour ago
That card is a standard IBM punched card that uses 12 positions for encoding. Each of the decimal digits is represented by a hole in one of 10 positions. Each letter is represented by a hole in one of three extra positions and one of the digit positions. Other characters are represented by two or three holes in various combinations. BCDIC is a way of compressing the 12 bit code of the card into only 6 bits.
– JeremyP
1 hour ago
I'm not sure what you mean by "how were A through F encoded". They were encoded in exactly the same way as on that punched card. This is a character encoding, not a number encoding.
– JeremyP
1 hour ago
I'm not sure what you mean by "how were A through F encoded". They were encoded in exactly the same way as on that punched card. This is a character encoding, not a number encoding.
– JeremyP
1 hour ago
add a comment |
Captain Man is a new contributor. Be nice, and check out our Code of Conduct.
Captain Man is a new contributor. Be nice, and check out our Code of Conduct.
Captain Man is a new contributor. Be nice, and check out our Code of Conduct.
Captain Man is a new contributor. Be nice, and check out our Code of Conduct.
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See en.wikipedia.org/wiki/EBCDIC for a start, and note the relationships with punched cards and not wanting holes too close to each other for structural integrity.
– Jon Custer
7 hours ago
@JonCuster thanks for the insight, can you post the relation with punch cards as an answer so I can give it an upvote? If you would rather not I can post it myself, I just don't want you to feel like I'm "stealing" it.
– Captain Man
6 hours ago
feel free to steal! It has been a long time since I used punch cards (or dropped them on the floor).
– Jon Custer
6 hours ago
I'm not convinced by logic about avoiding card damage, for two reasons. One is that you often get long runs of holes in the top three rows from alphabetic data. The other is that IBM also used "column binary" format cards where the 24 positions in two rows represented 3 8-bit bytes. Storing binary data (e.g. executable file images) in that format, about 50% of the holes on every card were punched, and that never gave any problems. (We used to ship executable code in column binary format to customers who didn't have any compatible mag tape drives, and it never gave us any transmission errors).
– alephzero
5 hours ago
Radix-sorting cards that contain nothing but letters, numbers, and blanks requires two passes per character position. The first pass sorts cards into one of ten bins based upon the bottom nine rows, and the second sorts them into one of four bins based on the top three. Using more complicated hole patterns would necessitate the use of more passes or more complicated sorting apparatus.
– supercat
5 hours ago