SBC Communications, Inc.-- What is probably the world's largest phone company monopoly. SBC consists of several RBOCs that were previously part of the Bell System, as well as a few other of its subsidiaries. Smell fishy? They also recently acquired the Prodigy Internet service.

A 3200-color "slow but cool" display mode in the Apple IIGS paint program DreamGrafix that used 80% of CPU time for updating the palette registers as the display was being drawn and 20% for actual processing.

Coincidentally, SBC is also an instruction on the Apple IIGS's 65816 processor (and its predecessor, the 6502) that performs subtraction, normally in binary. In 6502 processors with decimal mode, SBC subtracts in binary or packed binary-coded decimal depending on the decimal flag. To subtract without borrow, insert a SEC instruction before SBC, as SBC uses the carry bit as an inverted borrow bit.

  • Function: A + ~N + C => A (that is, A + (-N-1) + C => A)
  • Updates flags: S V . . . . Z C
  • Opcode numbers:
    (d,x) $E1
    dp    $E5
    imm   $E9
    abs   $ED
    (d),y $F1
    d,x   $F5
    a,y   $F9
    a,x   $FD

Similar: ADC | CMP | CPX | CPY
See also: 6502 instructions | 6502 addressing modes

An acronym meaning "Single Board Computer". A one stop shop for everything you need for a PC in a single package. These devices are typically used for embedded applications, but there are practical hobbyist uses for these as well. If you are thinking of building a set-top box/PVR, an portable MP3 player, or even a video game console, you will probably want to look into SBCs.

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