74161: Difference between revisions
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m (Created page with 'The '''74161''' is a 74-series logic 4-bit latch and upwards counter. All(?) known uses of it inside cartridges just use it as a latch. == 74161 Pinout == <pre> .--...') |
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The '''74161''' is a 74-series logic 4-bit latch and upwards counter. | The '''74161''' (common variants 74LS161, 74HC161) is a 74-series logic 4-bit latch and upwards counter. | ||
Several discrete logic [[mapper]]s use it as a latch. | |||
== 74161 Pinout == | == 74161 Pinout == | ||
<pre> | <pre> | ||
.--\/--. | .--\/--. | ||
/Clear - |01 16| - +5V | /Clear -o|01 16|-- +5V | ||
Clock - |02 15| - CarryOut | Clock --|02 15|-- CarryOut | ||
D0 - |03 14| - Q0 | D0 --|03 14|-- Q0 | ||
D1 - |04 13| - Q1 | D1 --|04 13|-- Q1 | ||
D2 - |05 12| - Q2 | D2 --|05 12|-- Q2 | ||
D3 - |06 11| - Q3 | D3 --|06 11|-- Q3 | ||
CountEnable - |07 10| - CarryIn | CountEnable --|07 10|-- CarryIn | ||
Gnd - |08 09| - /Load | Gnd --|08 09|o- /Load | ||
`------'</pre> | `------'</pre> | ||
== Signal descriptions == | == Signal descriptions == | ||
| Line 20: | Line 21: | ||
/Load causes Q to be set to the value of D on a low-to-high transition of Clock. | /Load causes Q to be set to the value of D on a low-to-high transition of Clock. | ||
[[Category:7400 series|161]] | |||
Revision as of 20:02, 5 April 2011
The 74161 (common variants 74LS161, 74HC161) is a 74-series logic 4-bit latch and upwards counter. Several discrete logic mappers use it as a latch.
74161 Pinout
.--\/--.
/Clear -o|01 16|-- +5V
Clock --|02 15|-- CarryOut
D0 --|03 14|-- Q0
D1 --|04 13|-- Q1
D2 --|05 12|-- Q2
D3 --|06 11|-- Q3
CountEnable --|07 10|-- CarryIn
Gnd --|08 09|o- /Load
`------'
Signal descriptions
While /Clear is low, Q is reset to 0.
When CountEnable and CarryIn are both high, a low-to-high transition on Clock increases the value of Q by 1, wrapping from 15 to 0.
CarryOut is high when CarryIn is high and Q is 15.
/Load causes Q to be set to the value of D on a low-to-high transition of Clock.
