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74ACT818

Fairchild Semiconductor
Part Number 74ACT818
Manufacturer Fairchild Semiconductor
Description 8-Bit Diagnostic Register
Published Apr 3, 2005
Detailed Description 74ACT818 8-Bit Diagnostic Register July 1988 Revised September 2000 74ACT818 8-Bit Diagnostic Register General Descrip...
Datasheet PDF File 74ACT818 PDF File

74ACT818
74ACT818

Overview
74ACT818 8-Bit Diagnostic Register July 1988 Revised September 2000 74ACT818 8-Bit Diagnostic Register General Description The ACT818 is a high-speed, general-purpose pipeline register with an on-board diagnostic register for performing serial diagnostics and/or writable control store loading.
The D-to-Y path provides an 8-bit parallel data path pipeline register for normal system operation.
The diagnostic register can load parallel data to or from the pipeline register and can output data through the D input port (as in WCS loading).
The 8-bit diagnostic register has multiplexer inputs that select parallel inputs from the Y-port or adjacent bits in the diagnostic register to operate as a right-shift-only register.
This register can then participate in a serial loop throughout the system where normal data, address, status and control registers are replaced with ACT818 diagnostic pipeline registers.
The loop can be used to scan in a complete test routine starting point (Data, Address, etc.
).
Then after a specified number of machine cycles it scans out the results to be inspected for the expected results.
WCS loading can be accomplished using the same technique.
An instruction word can be serially shifted into the shadow register and written into the WCS RAM by enabling the D output.
Features s On-line and off-line system diagnostics s Swaps the contents of diagnostic register and output register s Diagnostic register and diagnostic testing s Cascadable for wide control words as used in microprogramming s Edge-triggered D registers s Outputs source/sink 24 mA s ACT818 has TTL-compatible inputs s ACT818 is functionally- and pin-compatible to AMD Am29818 and MMI 74S818 Applications • Register for microprogram control store • Status register • Data register • Instruction register • Interrupt mask register • Pipeline register • General purpose register • Parallel-serial/serial-parallel converter Ordering Code: Order Number 74ACT818SPC Order Package N24C Package Descr...


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