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D Codes
D codes have multiple purposes. The first is to control the state of the light being on or off. Valid codes for light state are D01, D02, and D03.

  • D01: Light on for next move.

  • D02: Light off for next move.

  • D03: Flash (Light On, Light Off) after move (effect is limited to block in which appears, i.e. non-modal). You can also think of a D03 as D02, D01, D02 series of commands linked together.

  • D codes with values of 10 or greater represent the aperture's position on the list or wheel. It is very important to understand that there is no universal "D10" or "D30". Unlike the D01 , D02, and D03 counterparts which have a fixed meaning (draw, move, flash), D10 and higher values have aperture shapes and dimensions assigned to them by each individual user. Hence, one job's D10 could be a 10 mil Round, when another job's D10 could be a 45 mil Square.

    There are two distinct ways to number an aperture list. The traditional 24 aperture system started with D10 - D19, jumping suddenly to D70 - D71, then back to D20 - D29, ending with D72 -D73. This is still a common format for output for CAD packages, and is still mandatory for old 24 aperture Gerber vector Photoplotters.

    It is now common to start with D10, then increase numerically in steps of 1 (D10, D11, etc.) continuing up to D70 and beyond, rarely beyond 1000 individual apertures.

    D/A: Digital to Analog Converter
    The Digital to Analog (D/A) module accepts a series of binary numbers from the CPU and produces a corresponding analog signal. This is usually performed by pulse width modulation (PWM) that requires external filtering. A typical example of a D/A application would be the volume control on a television set.

    Data Formats
    Board outline data files should be created in the DXF format. If DXF format is unavailable, then Gerber photoplot format (with circular interpolation) is a good alternative. If Gerber format is used, the digit format should be leading zeros suppressed, and either inch units with two integer and four decimal digits (LZ2.4), or metric units with three integer and three decimal digits (LZ3.3).

    Note: At present Circuit Graphics is not able to make use of DXF files. Please supply board outline details in Gerber format.

    DMA: Direct Memory Access
    The Direct Memory Access (DMA) module is a co-processor that can transfer data between any two CPU-addressable locations without CPU intervention. Since I/O registers are memory-mapped, the DMA can read from or write to peripherals (such as SCI, SPI, or Timer) in two to four bus cycles - a vast improvement over the minimum 16 bus cycles needed for a traditional CPU interrupt routine.

    Additional features of the DMA include up to seven independent channels, up to 8 transfer sources, byte or word transfer capability, block or loop transfers, programmable bus bandwidth, CPU interrupt capability on transfer completion, and memory stretch capability for addresses beyond the 64 Kbyte internal memory map.

    Drill Data
    Most CAD packages offer a utility which will output a drill file in Excellon drill format (an industry standard). We require the ASCII version of this file, as opposed to EIA or Binary.

    Along with the drill file we require a report file which provides the finished hole size and total hole count for each tool change. Any non-plate through holes (NPTH) should also be clearly identified.

    The report file may be supplied as a separate ASCII text file or may be included as part of your

    Read_me.txt file.

    DTMF: Dual-Tone Multi-Frequency
    Dual-Tone Multiple Frequency (DTMF) transmitters incorporate a multi-functional tone generator which supports:

    DTMF dialing (the tone you hear when you press a number on a touch tone telephone)

    Melody-on-hold (generate a simple melody when you are on hold)

    Pacifier tone functions (acknowledge button pressed)

    Dual-Tone Multiple Frequency (DTMF) receivers can detect and qualify DTMF signals.

    EBI: External Bus Interface

    EEPROM: Electrically Erasable Programmable Read Only Memory

    EPROM: Erasable Programmable Read Only Memory

    Electrically Erasable Programmable Read Only Memory (EEPROM) and Erasable Programmable Read Only Memory (EPROM) are both types of ROM that can be programmed by the user. EPROM can be erased by exposing it to ultraviolet light, whereas EEPROM can be erased electrically (i.e., in the application). Once erased, EPROMs and EEPROMs may be reprogrammed with new instructions and data. EEPROM and EPROM information is non-volatile in that it does not change when power is removed.