外文翻譯--微型計(jì)算機(jī)的數(shù)字音頻接口processor-based數(shù)據(jù)記錄系統(tǒng)(編輯修改稿)
2025-06-26 06:54 本頁面
【文章內(nèi)容簡(jiǎn)介】 pling, a plugin puter board that multiplexes the 16bit data for transfer on the 8bit puter data bus, and an assembly language subroutine that controls the video cassette recorder (VCR) and directs storage of data in sequential memory locations. Two functional modes are available. In the interactive mode the VCR is started and the data array is filled repetitively until a key is pressed. The video tape is then rewound to a position 20 s before the beginning of the collected data. In the automatic mode the calling program provides a marker of 42 sequential, previously sampled data points. The VCR is started and ining data are pared with a portion of this marker. If a match is found the data array is filled with the data that immediately follow the marker. The video tape is then rewound to a position 20 s before the beginning of the data and control returns to the calling program. If no match is found within an adjustable period of playback (1 min to h), the video tape is rewound60 s and the subroutine returns a flag which indicates that data collection was not successful. If the last 42 data points of each record are used as the marker for the next record, sequential subroutine calls in the automatic mode will yield retrieval of contiguous blocks of data. Although the interface we describe is hardware specific to our instruments and puter, adaptation to other equipment should be straightforward. However, speed limitations of the 8255 interface chip appear to preclude use of this particular interface with IBM ATtype puters that operate at a 68 MHz clock speed. Our interface hardware is depicted in Fig. 1. Total cost for the puter board and additional ponents is $150. The digital output stage designed by Bezanilla provides word clocks for the right and left data channels and 16 parallel data lines. In our digital audio processor (DASS 501。 Unitrade Inc., Philadelphia, PA) these signals are available on a 25pin connector at the rear of the chassis. A ribbon cable extension is used to connect these lines to a similar connector mounted on one side of a 5 x x plastic box. Pointtopoint wiring within the box connects the data lines to a 37pin connector mounted on the opposite side of the box, connects the clock lines to a channel selector switch, and routes control lines for the VCR from the 37pin connector to a 5pin hex connector. A second ribbon cable extension connects the 37pin connector of the switch box to the matching connector of a plugin puter board. FIGURE 1 Electronic circuitry of digital interface. The parallel digital output of the digital audio processor is routed to ports A and B of an 8255 programmable peripheral interface chip on a P1012 puter board. The 8255 is programmed to convert each 16bit data word to two 8bit words for transfer on the puter bus. Wiring between a DB25 connector and a DC37 connector in the switch box facilitates connection of the digital audio processor to t
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