Year 2000 technical summary
E   Glossary of Terms << >>


   
  B

 
BCD
Acronym: Binary coded decimal
each 4 bit group is used to encode one decimal digit. This means that:
  • binary arithmetic needs special handling (typically a "decimal adjust" instruction is carried out after the ordinary binary operation to correct the answer)
  • each 4 bits means one digit, so an 8-bit byte can only store integers in the range [00-99] rather than [0-255], a 16-bit word [0000-9999] rather than [0-65535]
  • displaying BCD digits as ASCII requires trivial logic


BIOS
Acronym: Basic Input/Output System
The onboard system ROM chip which performs several tasks, including:
  • reset and initialization of hardware on reboot/power on (POST)
  • simple software interface to hardware devices such as disk and video
  • the loading of the OS bootstrap


 
   
  E

 
epoch
A reference point, or logical zero for time measurement. For example:
  • UNIX uses 1970-01-01 00:00:00Z as time=0, and counts seconds since that date
  • MS-DOS counts days since 1980-01-01
  • NTP counts seconds since 1900-01-01 00:00:00Z


 
   
  N

 
NTP
Acronym: Network Time Protocol.
A protocol for maintaining correct time across computer networks, as specified in RFC 1305 (version 3 of NTP).
See also XNTP

 
   
  P

 
POST
Acronym: Power On Self Test
The series of procedures run by the BIOS when the machine is powered up. This includes checking for presence of hardware, hardware faults, and reading the RTC to determine the current date and time.

 
   
  R

 
RFC
Acronym: Request For Comment
Internet technical documents. See Appendix G §G.4 (References , Standards)

RTC
Acronym: Real Time Clock
A battery backed chip inside PCs which maintains the correct time and date when the machine is powered off.

 
   
  W

 
Win16
The name given to the software interface offered by a 16 bit Windows OS. This includes functions, data structures. See Chapter 3 §3.3.1 (OS Issues, Win16 API).

Win32
The name given to the software interface offered by a 32 bit Windows OS. This includes functions, data structures. See Chapter 3 §3.3.3 (OS Issues, Win32 API).

 
   
  X

 
XNTP
An implementation of NTP, RFC 1305 (NTP version 3).

 

 

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