“Code page 858”的意思、由来-开放百科全书

Code page 858 was created from code page 850 in 1998 by changing code point 213 (D5_hex) from dotless i ‹ı› to the euro sign ‹€›.^[1]

Still, instead of adding support for the new code page 858, IBM's PC DOS 2000, also released in 1998, changed the definition of the existing code page 850 to what IBM called modified code page 850 to include the euro sign at code point 213.^[5]^[6]^[7]^[8]^[9]^[10] More recent IBM/MS products implemented codepage 858 under its own ID.

Character set

The following table shows code page 858. Each character appears with its equivalent Unicode code-point. The decimal value of the location is the Alt code. Only the second half of the table (code points 128–255) is shown, the first half (code points 0–127) being the same as code page 437.

Notes

1. ^¹The reason for this might have been down to existing restrictions in the implementation of the codepage switching logic under MS-DOS/PC DOS, which limited .CPI files to 64 KB in size or about six codepages maximum, a limitation, which was circumvented in some OEM versions of MS-DOS, in Windows NT, and also does not exist in DR-DOS. Further, the parser in MS-DOS/PC DOS limits the number of possible country / codepage entries in COUNTRY.SYS files to a maximum of 146 or 438, a limitation non-existent in DR-DOS. So, adding support for codepage 858 might have meant to drop another (e.g. codepage 850) at the same time, which might not have been a viable solution at that time, given that some applications were hard-wired to use codepage 850.
2. ^¹²{{cite web |url=http://www-01.ibm.com/software/globalization/cp/cp00858.html |title=00858 |work=Code pages by CPGID |publisher=IBM |access-date=2011-11-20 |dead-url=no |archive-url=https://web.archive.org/web/20160820152600/https://www-01.ibm.com/software/globalization/cp/cp00858.html |archive-date=2016-08-20}} [https://www-03.ibm.com/systems/resources/systems_i_software_globalization_pdf_cp00858z.pdf]
3. ^¹{{cite web |title=IBM00858 |publisher=IANA |url=https://www.iana.org/assignments/charset-reg/IBM00858 |access-date=2016-12-06 |dead-url=no |archive-url=https://web.archive.org/web/20161206141348/https://www.iana.org/assignments/charset-reg/IBM00858 |archive-date=2016-12-06}}
4. ^¹{{cite web |title=Changing codepages in FreeDOS |author-first=Matthias |author-last=Paul |date=2001-08-15 |access-date=2013-05-08 |url=http://www.freedos.org/technotes/technote/txt/141.txt |type=Technical design specification based on fd-dev post https://archive.is/3yUpW --> |dead-url=yes |archive-url=https://web.archive.org/web/20160820152328/http://www.freedos.org/technotes/technote/txt/141.txt |archive-date=2016-08-20 |quote=The new official ID for the Multilingual "codepage 850 with EURO SIGN" is 858, not 850. IBM will switch to use 858 instead of their 850 variant with future issues of their products. […] I can only guess why they didn't add 858 to their EGAx.CPI, COUNTRY.SYS, and KEYBOARD.SYS files in PC DOS 2000. Many third-party applications are designed to work with 850 and didn't know about 858 at the time PC DOS 2000 was released, so it's easier for everyone, but unfortunately it's not compatible. […] As explained above, COUNTRY.SYS and KEYBOARD.SYS contain only two codepage entries for a given country in Western issues of DOS. (In Arabic and Hebrew issues there can be up to 8 codepages for one country, in theory there is no limit below the range of allowed codepages 1..65534). […] The problem is that removing support for 850 might have caused compatibility problems with applications which are hard-wired to use 850. Adding 858 as a third choice to all the files would have increased the file and table sizes significantly. The COUNTRY.SYS file parser in MS-DOS/PC DOS IO.SYS/IBMBIO.COM sets aside a 6 Kb (for DOS 6) scratchpad to load all the info. This allows a maximum of 438 entries in a COUNTRY.SYS file to be accepted, otherwise you will get the message "COUNTRY.SYS too large.". The NLSFUNC parser does not have this limitation, and the file parsers in DR-DOS (kernel and NLSFUNC) also do not know of such a restriction. Older issues of MS-DOS/PC DOS even had a 2 Kb buffer for a maximum of 146 entries.}}
5. ^¹{{cite web |title=Changing codepages in FreeDOS (follow-up) |author-first=Matthias |author-last=Paul |date=2001-08-27 |access-date=2013-05-08 |url=http://marc.info/?l=freedos-dev&m=99895886029809&w=2 |archive-url=https://archive.is/G3y2F |archive-date=2014-10-01 |quote=[…] one could also create custom .CPI files in the traditional FONT style without difficulties, but you could only store up to […] six codepages in such a file if it should be usable by MS-DOS/PC DOS (some OEM issues and NT can handle files larger than 64 Kb, but MS-DOS/PC DOS can not).}}
6. ^¹{{cite web |author-first=Yuri |author-last=Starikov |url=http://rdos401.org/ |title=15-летию Russian MS-DOS 4.01 посвящается |trans-title=15 Years of Russian MS-DOS 4.01 |language=Russian |date=2005-04-11 |access-date=2014-05-07 |dead-url=no |archive-url=https://web.archive.org/web/20160820152108/http://rdos401.org/ |archive-date=2016-08-20}}
7. ^¹{{cite web |title=DOS COUNTRY.SYS file format |type=COUNTRY.LST file |author-first=Matthias |author-last=Paul |date=2001-06-10 |edition=1.44 |orig-year=1995 |url=http://www.columbia.edu/~em36/wpdos/MatthiasPaulCPI.zip |access-date=2016-08-20 |dead-url=no |archive-url=https://web.archive.org/web/20160420065252/http://www.columbia.edu/~em36/wpdos/MatthiasPaulCPI.zip |archive-date=2016-04-20}}
8. ^¹{{cite web |title=Format description of DOS, OS/2, and Windows NT .CPI, and Linux .CP files |type=CPI.LST file |author-first=Matthias |author-last=Paul |date=2001-06-10 |edition=1.30 |orig-year=1995 |url=http://www.columbia.edu/~em36/wpdos/MatthiasPaulCPI.zip |access-date=2016-08-20 |dead-url=no |archive-url=https://web.archive.org/web/20160420065252/http://www.columbia.edu/~em36/wpdos/MatthiasPaulCPI.zip |archive-date=2016-04-20}}

Character set

Notes

References