74ACT818SPC

Maximum Clock Frequency :
Supply Voltage - Max : 5.5 V
Maximum Operating Temperature : + 85 C
Logic Type : CMOS
Packaging : Tube
Number of Circuits : Single
Package / Case : PDIP-24
High Level Output Current : - 24 mA
Low Level Output Current : 24 mA
Logic Family : ACT
Propagation Delay Time : 13 ns


Features:

On-line and off-line system diagnostics
Swaps the contents of diagnostic register and output register
Diagnostic register and diagnostic testing
Cascadable for wide control words as used in microprogramming
Edge-triggered D registers
Outputs source/sink 24 mA
ACT818 has TTL-compatible inputs
ACT818 is functionally- and pin-compatible to AMD Am29818 and MMI 74S818


Application

• Register for microprogram control store
• Status register
• Data register
• Instruction register
• Interrupt mask register
• Pipeline register
• General purpose register
• Parallel-serial/serial-parallel converter


Pinout




Specifications

Supply Voltage (V_CC).................. −0.5V to +7.0V
DC Input Diode Current (I_IK)
    V_I = −0.5V ......................................... −20 mA
    V_I = VCC + 0.5V................................. +20 mA
DC Input Voltage (V_I) .........−0.5V to V_CC + 0.5V
DC Output Diode Current (I_OK)
    V_O = −0.5V........................................  −20 mA
    V_O = V_CC + 0.5V +20 mA
DC Output Voltage (V_O) ......−0.5V to V_CC + 0.5V
DC Output Source
    or Sink Current (I_O)............................ ±50 mA
DC V_CC or Ground Current
    per Output Pin (I_CC or I_GND)............... ±50 mA
Storage Temperature (T_STG)... −65°C to +150°C
Junction Temperature (T_J)
    PDIP ......................................................140°C


Description

The 74ACT818SPC 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 of the 74ACT818SPC 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 of the 74ACT818SPC 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 of the 74ACT818SPC 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.