SN74ALS870NT

双16 ×4寄存器文件 DUAL 16-BY-4 REGISTER FILES

description

This device features two 16-word by 4-bit register files. Each register file has individual write-enable 1W, 2W controls and address lines. This device has two 4-bit data I/O ports DQA1–DQA4 and 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 and output to bus B, or output to bus A and receive input from bus B. To prevent writing conflicts in the dual-input mode, the B-input port takes priority. Two select S0 and S1 lines control which port has access to which register. S2 determines whether the A ports are in the 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 internal 1-of-16 decoder to select which register word is to be accessed. All outputs are 3-state buffer-type outputs designed specifically to drive bus lines directly.

The SN74ALS870 is characterized for operation from 0°C to 70°C.

• 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