Unidirectional Parallel Ports
In early parallel ports the data lines were unidirectional (data out only) so it was not easily possible to feed data in to the computer. However, a workaround was possible by using 4 of the 5 status lines. A circuit could be constructed to split each 8-bit byte into two 4-bit nibbles which were fed in sequentially through the status lines. Each pair of nibbles was then re-combined into an 8-bit byte. This same method (with the splitting and recombining done in software) was also used to transfer data between PCs using a laplink cable.
Read more about this topic: Parallel Port
Famous quotes containing the words parallel and/or ports:
“The parallel between antifeminism and race prejudice is striking. The same underlying motives appear to be at work, namely fear, jealousy, feelings of insecurity, fear of economic competition, guilt feelings, and the like. Many of the leaders of the feminist movement in the nineteenth-century United States clearly understood the similarity of the motives at work in antifeminism and race discrimination and associated themselves with the anti slavery movement.”
—Ashley Montagu (b. 1905)
“O polished perturbation! golden care!
That keep’st the ports of slumber open wide
To many a watchful night.”
—William Shakespeare (1564–1616)