SN74ALS870 DUAL 16-BY-4 REGISTER FILES

SDAS139A - DECEMBER 1982 - REVISED JANUARY 1995

features

• 3-State Buffer-Type Outputs Drive Bus Lines Directly
• Each Register File Has Individual Write-Enable Controls and Address Lines
• Designed Specifically for Multibus Architecture and Overlapping File Operations
• Prioritized B-Input Port Prevents Write Conflicts During Dual-Input Mode
• Package Options Include Plastic Small-Outline (DW) Packages and Standard Plastic (NT) 300-mil DIPs

description

This device features two 16-word by 4-bit register files. Eachregister file has individual write-enable (1W\, 2W\) controls andaddress lines. This device has two 4-bit data I/O ports (DQA1-DQA4and DQB1-DQB4). The data I/O ports can output to bus A and bus B,receive input from bus A and bus B, receive input from bus A andoutput to bus B, or output to bus A and receive input from bus B. Toprevent writing conflicts in the dual-input mode, the B-input porttakes priority. Two select (S0 and S1) lines control which port hasaccess to which register. S2 determines whether the A ports are inthe input or the output modes and S3 does likewise for the B ports.The address lines (1A0-1A3 or 2A0-2A3) are decoded by an internal1-of-16 decoder to select which register word is to be accessed. Alloutputs are 3-state buffer-type outputs designed specifically todrive bus lines directly.

The SN74ALS870 is characterized for operation from 0°C to70°C.

View more information about generic part numbers:SN74ALS870

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