8:1 data selector with 4mA output drive
The MM74HCT251N: It selects one of eight data inputs and routes it to a single output, with the select lines controlled by a three-bit address. The 4mA output high and low drive current is typical for HCT logic — enough to drive one or two standard TTL loads or a CMOS input stage directly, but not a long backplane trace without a buffer. The through-hole 16-DIP package (0.300" body width, 7.62mm pitch) is breadboard- and socket-friendly, making this part a common choice for prototyping, retrofits, and legacy board repairs where a surface-mount rework is impractical. The 16-PDIP supplier package is the same mechanical outline — no footprint ambiguity.
Temperature grade and supply rails
The single-supply requirement means no separate VCC for the select logic; the address and data lines all reference the same rail.