key_scan.tan.summary

程序主要是用硬件描述语言（VHDL）实现： 4*4键盘扫描

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Timing Analyzer Summary
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Type           : Worst-case tsu
Slack          : N/A
Required Time  : None
Actual Time    : 5.400 ns
From           : p0
To             : FPGA_S51_0:inst5|latch_address[0]
From Clock     : 
To Clock       : ALE
Failed Paths   : 0

Type           : Worst-case tco
Slack          : N/A
Required Time  : None
Actual Time    : 16.600 ns
From           : Keyboard:inst|SCN[0]
To             : scan[0]
From Clock     : clock
To Clock       : 
Failed Paths   : 0

Type           : Worst-case th
Slack          : N/A
Required Time  : None
Actual Time    : 0.900 ns
From           : p7
To             : FPGA_S51_0:inst5|latch_address[7]
From Clock     : 
To Clock       : ALE
Failed Paths   : 0

Type           : Clock Setup: 'clock'
Slack          : N/A
Required Time  : None
Actual Time    : 74.07 MHz ( period = 13.500 ns )
From           : Keyboard:inst|Clock_1[5]
To             : Keyboard:inst|Clock_1[0]
From Clock     : clock
To Clock       : clock
Failed Paths   : 0

Type           : Total number of failed paths
Slack          : 
Required Time  : 
Actual Time    : 
From           : 
To             : 
From Clock     : 
To Clock       : 
Failed Paths   : 0

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