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Electrical Skew Adjustment Technique

IP.com Disclosure Number: IPCOM000080232D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Sorensen, WD: AUTHOR [+2]

Abstract

Data records on computer tape typically have bits arranged in parallel bytes across the tape using 7 or 9 tracks, with successive bytes in a block of data spaced 100 microseconds apart when the tape is traveling at the operating speed. In a device having display of 7 element light-emitting diode (LED) units, electrical skew may be adjusted without an oscilloscope.

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Electrical Skew Adjustment Technique

Data records on computer tape typically have bits arranged in parallel bytes across the tape using 7 or 9 tracks, with successive bytes in a block of data spaced 100 microseconds apart when the tape is traveling at the operating speed. In a device having display of 7 element light-emitting diode (LED) units, electrical skew may be adjusted without an oscilloscope.

Adjustment is first made for read skew using a master skew tape having bits precision recorded in each track in each byte position of a data block, and thereafter the write skew adjustment is effected.

To adjust for read electrical skew, the master skew tape is read to determine the duration of the single-shot on the center track. Raw data is sampled to determine the rise time or the occurrance of a transition, as indicated by point A of Fig. 1. When this is determined, the program delays to point B whereupon consecutive reads are taken. The single-shot duration, which may vary from 3 to 33 microseconds, is adjusted to a midrange value of 16 to 20 microseconds. This adjustment is accomplished by adjusting the potentiometer indicated by the LED display, shown at Fig. 2, until the indicated data pulse duration is within the desired midrange value.

Thereafter each of the other tracks are adjusted to correspond to the reference, center track. As shown in Fig. 3, each track is adjusted to align the fall of the pulse being adjusted with the fall of the center track pulse, as indicated at point C. This is accomplished using the LED display as shown in Fig. 4. The numeral at the left side of the display indicates the potentiometer to adjust. The bars of the three LED 7 bar...