7495: Shift Register, 4 Bits (Parallel In, Parallel Out)

This is a 4-bit shift register with outputs and inputs on all stages. Depending on how you use it, you can parallel load data or shift information to the right. By making external feedback connections, you can also shift information to the left.

To use this chip as a parallel-load, right-shift-only device, hold SLT pin 8 low. Data may be entered on the A, B, C, D inputs when the Mode control pin 6 is made high. Data is immediately entered asynchronously.

Data will be shifted to the right if the Mode control pin 6 is made low. Shifting takes place on the positive to ground (negative edge) transition of SRT, pin 9.

During the right shift mode, informatlon at the serial A_in input is entered into the first register stage (Stage A). On a shift right, the contents of A_in go to QA. The contents of QA go to QB; the contents of QB go to QC; and the contents of QC go to QD. The contents of QD are destroyed or passed onto a following package.

You can convert this into a shift-right-shift-left register by making external connections from QD to C; from QC to B; from QB to A and from QA to the serial input. In this mode, if you make the Mode control pin 6 high and provide a positive to ground transition on the SLT input pin 8, the information shifts to the left. Making the Mode control low and providing a positive to ground transition on the SRT input shifts data to the right.

Thus, with the external connections, the chip acts as a two-clock right/left register. Without the external connections, the chip acts as a parallel load, shift right only, parallel out register.

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