| 摘要 |
<p>An encoder is provided for encoding fixed length binary words into (VWL) encoded serial data in which each non-zero word comprises a start bit and an end bit of one state and a number of intervening bits of a different state, the number of such bits representing the magnitude of the word. In a preferred embodiment the coder comprises a multiplexer (10), a PROM (12) and a flip-flop (14). The PROM (12) provides a feedback signal comprising three parts - a control signal, a binary word representing the magnitude of the input word, and an output signal having either of two states. The feedback signal is repeatedly applied to the PROM (12) by the multiplexer(10). The PROM (12) responds by reducing the magnitude part of the feedback signal by one. Each time the cycle repeats, another bit appears at the output (22) of the coder as the output signal. Accordingly, the number of such output bits corresponds to the magnitude of the input word. Eventually, when the magnitude has been reduced to zero, the multiplexer selects a new word to apply to the PROM (12).</p> |
