F(_______________) G(________) J(__________) K(__________) M(__________) Z(__________)
The counter may be preset by entering the desired data on the DATA A, DATA B, DATA C, and DATA D inputs. When the LOAD input is taken low the data is loaded independently of either clock input. This feature allows the counter to be used as divide-by-n counters by modifying the count length with the preset inputs.
In addition the counter can also be cleared. This is accomplished by inputting a high on the CLEAR input. All 4 internal stages are set to a low level independently of either COUNT input. Both a BORROW and CARRY output are provided to enable cascading of both up and down counting functions. The BORROW output produces a negative going pulse when the counter underflows and the CARRY outputs a pulse when the counter overflows. The counter can be cascaded by connecting the CARRY and BORROW outputs of one device to the COUNT UP and COUNT DOWN inputs, respectively, of the next device.
All inputs are protected from damage due to static discharge by diodes to VCC and ground.
1.请将第一段翻译成中文。(12分)
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