Editing Talk:2697: Y2K and 2038

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:::{{w|Binary-coded decimal}}... Loads of interesting uses (including precision decimal fractions), but of course largely fallen out of favour for various technical and logistial reasons.  [[Special:Contributions/172.70.86.61|172.70.86.61]] 14:44, 14 November 2022 (UTC)
 
:::{{w|Binary-coded decimal}}... Loads of interesting uses (including precision decimal fractions), but of course largely fallen out of favour for various technical and logistial reasons.  [[Special:Contributions/172.70.86.61|172.70.86.61]] 14:44, 14 November 2022 (UTC)
 
:The first computerised passport system for the UK had a y2K issue. In fact, it was designed in, because it was supposed to be replaced before 1999. Unfortunately, progress with its replacement was running late. We thought that we could get away with two digits for certain dates because the software was going to be thrown away before the end of 1999. And yes, two digit years were common in COBOL programs because decimal numbers coded using ASCII or EBCDIC were the default for numeric data. [[User:Jeremyp|Jeremyp]] ([[User talk:Jeremyp|talk]]) 15:32, 13 November 2022 (UTC)
 
:The first computerised passport system for the UK had a y2K issue. In fact, it was designed in, because it was supposed to be replaced before 1999. Unfortunately, progress with its replacement was running late. We thought that we could get away with two digits for certain dates because the software was going to be thrown away before the end of 1999. And yes, two digit years were common in COBOL programs because decimal numbers coded using ASCII or EBCDIC were the default for numeric data. [[User:Jeremyp|Jeremyp]] ([[User talk:Jeremyp|talk]]) 15:32, 13 November 2022 (UTC)
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:Numbers stored as characters is a basic data type on IBM mainframes (look up Zoned Decimal and Packed Decimal). The processor itself has instructions to compute directly in those formats. It has the advantage to save a lot of processing time, as there is basically no conversion from user input nor for display. Also avoid precision errors that floating point formats have. And way easier to read on memory dumps. The waste of space (using a whole byte to store a single digit) is not much of an issue considering even early computers could save kilometres of data on tapes. Having the programs run fast was more important. [[User:Shirluban|Shirluban]]  [[Special:Contributions/172.71.126.41|172.71.126.41]] 17:17, 15 November 2022 (UTC)
 
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:1. Having done programming since 1966, I know that much data was stored on 80-character cards (and way before that year and the IBM System/360) and using 2 characters (2.5% of the card) to store the "19" was not acceptable. As processes moved into the tape and disk world, human nature tended to not expand the field to 4 characters (the future is a long way off until, suddenly, it isn't). [[Special:Contributions/172.70.178.65|172.70.178.65]] 07:57, 13 November 2022 (UTC)
 
:1. Having done programming since 1966, I know that much data was stored on 80-character cards (and way before that year and the IBM System/360) and using 2 characters (2.5% of the card) to store the "19" was not acceptable. As processes moved into the tape and disk world, human nature tended to not expand the field to 4 characters (the future is a long way off until, suddenly, it isn't). [[Special:Contributions/172.70.178.65|172.70.178.65]] 07:57, 13 November 2022 (UTC)

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