Hardware code page

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In computing, a hardware code page (HWCP) refers to a

graphics mode
are displayed in a computer's default hardware code page.

Code page assignments

In North American

CMOS setup.[15] However, some of the display adapters designed for Eastern European, Arabic and Hebrew PCs supported multiple software-switchable hardware code pages, also named font pages,[1] selectable via I/O ports[4] or additional BIOS functions.[12][13]

In contrast to this, printers frequently support several user-switchable character sets, often including various variants of the 7-bit

ISO/IEC 646-US / ASCII"[1]), sometimes also a couple of 8-bit code pages like code page 437,[10][16][17] 850,[10][16][17] 851,[10] 852,[10][18] 853,[19] 855,[10][18] 857,[19] 860,[10][16][17] 861,[17] 863,[10][16][17] 865,[10][16][17] and 866.[10][18][20][21] Printers for the Eastern European or Middle Eastern markets sometimes support other locale-specific hardware code pages to choose from. They can be selected via DIP switches or configuration menus on the printer, or via specific escape sequences.[1][nb 2]

Support in operating systems

When operating systems initialize their code page switching logic, they need to know but have no means to determine the previously active hardware code page by themselves. Therefore, for code page switching to work correctly, the hardware code page needs to be specified.[1][22][23][24]

Under DOS and Windows 9x this is accomplished by specifying the hardware code page as a parameter (hwcp) to the device drivers DISPLAY.SYS and PRINTER.SYS in CONFIG.SYS: 

DEVICE=…\DISPLAY.SYS CON=(type,hwcp,n|(n,m))[1][2][22][23][24][25][26]

DEVICE=…\PRINTER.SYS PRN=(type,hwcp,n)[1][22][23][24][25][26]

If multiple hardware code pages are supported in OEM issues, the first hardware code page (hwcp1) in the list specifies the default hardware code page: 

DEVICE=…\DISPLAY.SYS CON=(type,(hwcp1,hwcp2,…),n|(n,m))[9]
DEVICE=…\PRINTER.SYS PRN=(type,(hwcp1,hwcp2,…),n)[9]

If no hardware code page(s) are specified, these drivers default either to a dummy code page number 999

COUNTRY directive or assumed to be the operating system's internal default, usually 1 (US) in Western issues of DOS).[1]
In many English-speaking countries, the primary code page is either 437 (f.e. in the US) or 850 (f.e. in the UK, Ireland and Canada),[23][24] so that, without specifying a different code page, the system would often assume one of these to be the corresponding device's default hardware code page as well.[1]

If a hardware code page does not match one of those with official code page assignments, an arbitrary number from the range 57344–61439 (E000h–EFFFh) for

IBM CDRA
to give the operating system a non-conflictive "handle" to select that code page.

Hebrew MS-DOS do not use DISPLAY.SYS and PRINTER.SYS, but provide similar facilities using ARABIC.COM, HEBREW.COM, and SK_HGC.COM.[9]

OEM code pages

Hardware code pages are also

OEM code pages. The designation "OEM", for "original equipment manufacturer", indicates that the character set could be changed by the manufacturer to meet different markets.[28][29]

However, OEM code pages do not necessarily reside in ROM, but include so called prepared code pages,

VGA,[38][13] etc.) and printers as well.[39][40][41][42][43]
Hence, the group of OEM code pages is a superset of hardware code pages.

See also

  • PC-9800 series
  • Alt codes

Notes

  1. HP OmniBook 300 uses code page 850 (rather than the more common code page 437
    ) as hardware code page.
  2. ^ On Epson, NEC and Fujitsu ESC/P compatible printers, the escape sequence to switch to various hardware code pages is ESC R (n) with (n) = 0..254 being a code associated with specific character sets. The range of supported codes depends on the printer model and installed font options.

References

  1. ^
    DEVICE=…\display.sys con=(ega,437,1) […] DISPLAY.SYS is told that 437 should be assumed to be the hardware codepage of the display adapter. This is necessary to be known by DISPLAY.SYS because it will use different mechanisms to switch to the software prepared codepages and the hardware codepage, and there is no way to retrieve the info about the hardware codepage by itself. When the requested codepage is equal to the hardware codepage declared here, DISPLAY.SYS will use the method to switch to the hardware codepage, otherwise it will attempt to look up the font info in its internal buffer. […] (NB. Based on fd-dev post [1]
    .)
  2. ^ a b c "Changing code pages". XyWrite III, XyWrite III Plus and Signature. 2009-04-25 [2002-09-04]. Application Note #111. Archived from the original on 2016-06-12. Retrieved 2016-06-12.
  3. ISBN 0-201-57760-7
    .
  4. ^ a b c d Elliott, John C. (2020-06-08). "Monochrome Display Adapter: Notes". Seasip.info. Archived from the original on 2023-09-20. Retrieved 2016-11-23. […] Reading from port 03BAh returns vertical sync in bit 7, and a card ID in bits 6-4: 000: Hercules, 001: Hercules Plus, 101: Hercules InColor, 111: Unknown clone […] One card […] which appears to be a Hercules clone of Eastern European origin, has a further capability - two ROM fonts, selectable in software. These options are controlled in a similar manner to other extended features in the Hercules: Bit 2 of port 3BFh must be set to enable the feature, and then Bit 4 of port 3B8h selects which font to use. The card ID in bits 6-4 of port 03BAh has all three bits set. […]
  5. ^
    Hewlett-Packard Company
    , Portable Computer Division. August 1985. 45559-90001. Retrieved 2016-11-27.
  6. ^
    Hewlett-Packard Company. December 1986 [August 1985]. 45559-90006. Archived
    (PDF) from the original on 2016-11-28. Retrieved 2016-11-27.
  7. ^
    LICS, the Lotus International Character Set
    . Most LICS characters are included in code page 850; the few that are not will not display […] If your HP 95LX cannot display […] or if your printer cannot print a LICS character, the HP 95LX uses a fallback presentation for that character […] if you use the © symbol and your printer cannot print it, the HP 95LX might display (c) or c as the fallback presentation (depending on the capabilities of your printer).
  8. ^ Paul, Matthias R. (2002-09-05). "Technical info on undocumented DOS country info for LCASE, ARAMODE and CCTORC records". FreeDOS development list fd-dev at Topica. Archived from the original on 2016-05-27. Retrieved 2016-05-26.
  9. ^ a b c d Paul, Matthias R. (2002-12-04). "DISPLAY CON". FreeDOS development list freedos-dev. Archived from the original on 2017-09-09. Retrieved 2016-06-07.
  10. ^
    Fujitsu Limited. April 1994. C147-E015-01EN. Archived
    (PDF) from the original on 2016-06-14. Retrieved 2016-06-14.
  11. NEC Deutschland GmbH
    , May 1992
  12. ^
    DJ Delorie. Archived
    from the original on 2016-06-09. Retrieved 2016-06-09.
  13. ^
    Brown, Ralf D. (2012-01-21) [2000-07-16]. "Public Files on FTP.CS.CMU.EDU - The x86 Interrupt List aka "Ralf Brown's Interrupt List" (RBIL)". Archived
    from the original on 2016-06-16. Retrieved 2016-06-16.
  14. Ziff Davis, Inc.
    : 196–199. Retrieved 2017-08-12.
  15. ^
    Hewlett-Packard Singapore (Private) Limited, Asia-Pacific Personal Computer Division. October 1996. pp. 21-6 – 21-7, 25-9 – 25-13, 26-14 – 26-18, C-1 – C-4, D-1 – D-10. 1216-90001. Archived (PDF) from the original on 2016-11-30. Retrieved 2016-11-29. Your palmtop supports code pages 850 and 437. The built-in applications (except 1-2-3) and System Manager
    -compliant applications […] use code page 850. […] Any DOS application you load and run will by default use code page 437. If an application requires code page 850, you can select it using the Setup utility.
  16. ^
    NEC Deutschland GmbH
    . November 1990.
  17. ^
    Epson Deutschland GmbH
    . 1991.
  18. ^
    NEC Deutschland GmbH
    . March 1993.
  19. ^
    Epson Deutschland GmbH
    . 1992.
  20. ^ bhd (2016-06-04) [1995]. "FreeBSD Handbook". The FreeBSD Documentation Project. 48895. Chernov, Andrey. 22.4.1. Localization - i18n/L10n Usage and Setup: Locale Configuration for Specific Languages: Russian Language (KOI8-R Encoding). Archived from the original on 2016-06-12. Retrieved 2016-06-12.
  21. ^ bhd (2016-06-04) [1995]. "FreeBSD Handbook". The FreeBSD Documentation Project. 48895. Chernov, Andrey. 22.5.1.3 Localization - i18n/L10n Usage and Setup: Localizing FreeBSD to Specific Languages: Russian Language (KOI8-R Encoding): Printer Setup. Archived from the original on 2016-06-12. Retrieved 2016-06-12.
  22. ^
    Caldera, Inc. 1998 [1993, 1997]. Archived from the original
    on 2016-06-07.
  23. ^
    OpenDOS 7.01
    , including the description of many undocumented features and internals. It is part of the author's yet larger MPDOSTIP.ZIP collection maintained up to 2001 and distributed on many sites at the time. The provided link points to a HTML-converted older version of the NWDOSTIP.TXT file.)
  24. ^ a b c d e Paul, Matthias R. (2001-04-09). NWDOS-TIPs — Tips & Tricks rund um Novell DOS 7, mit Blick auf undokumentierte Details, Bugs und Workarounds. Release 183 (in German) (3 ed.). MPDOSTIP.
  25. ^
    Caldera, Inc. 1998 [1993, 1997]. Archived from the original
    on 2016-06-09.
  26. ^
    PC Magazine
    : 327–328. Retrieved 2016-06-09.
  27. ^ Paul, Matthias R. (2001-06-10) [1995]. "DOS COUNTRY.SYS file format" (COUNTRY.LST file) (1.44 ed.). Archived from the original on 2016-04-20. Retrieved 2016-08-20.
  28. Chen, Raymond (2005-03-08). "Keep your eye on the code page". The Old New Thing. Microsoft. Archived
    from the original on 2016-06-12. Retrieved 2016-06-12.
  29. Chen, Raymond (2005-08-29). "Why is the default console codepage called "OEM"?". The Old New Thing. Microsoft. Archived
    from the original on 2016-06-12. Retrieved 2016-06-12.
  30. ISBN 3-89319-110-0
    . VVA-Nr. 563-00110-4.
  31. NEC Corporation. part number 819-000104-3001. Archived
    (PDF) from the original on 2016-11-25. Retrieved 2016-11-25.
  32. Ziff Davis, Inc.
    : 121–133.
  33. ^
    ISBN 1-55615-103-9. (NB. The second edition does no longer discuss the InColor and MCGA
    cards at detail level.)
  34. ^ Elliott, John C. (2012-08-09). "Hercules Graphics Card Plus: Notes". Seasip.info. Archived from the original on 2016-11-23. Retrieved 2016-11-23.
  35. ^ Elliott, John C. (2012-08-05). "Hercules InColor Card: Notes". Seasip.info. Archived from the original on 2016-11-23. Retrieved 2016-11-23.
  36. ^ CW (1988-04-22). "Hercules bringt neues PC-Board mit Ramfont: Grafik und Netzwerk auf einer Karte". Computerwoche (in German). Archived from the original on 2017-09-09. Retrieved 2016-11-24.
  37. Ziff Davis, Inc.
    1988-05-31. Retrieved 2016-11-24.
  38. ^
    EAN 9780201624908
    .
  39. ^ Paul, Matthias R. (2001-06-10) [1995]. "Format description of DOS, OS/2, and Windows NT .CPI, and Linux .CP files" (CPI.LST file) (1.30 ed.). Archived from the original on 2016-04-20. Retrieved 2016-08-20.
  40. ^ Elliott, John C. (2006-10-14). "CPI file format". Seasip.info. Archived from the original on 2016-09-22. Retrieved 2016-09-22.
  41. Brouwer, Andries Evert (2001-02-10). "CPI fonts". 0.2. Archived
    from the original on 2016-09-22. Retrieved 2016-09-22.
  42. ISBN 978-0-596-10242-5
    .
  43. ISBN 1-55615-329-5
    .
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