Description:

Lot of 5 logic ICs marked 74FCT240AP (FCT family). This is an octal inverting buffer/line driver with 3-state outputs, commonly used to isolate buses, increase drive strength, and provide clean digital buffering in 5V TTL/CMOS systems. Through-hole PDIP-20 package—great for retro computing, industrial control repairs, and breadboard/prototyping.

Features & Specifications:

- Part number: 74FCT240AP

- Function: Octal inverting buffer / line driver

- Outputs: 3-state (tri-state)

- Channels: 8

- Control: Two output-enable pins (OE\) controlling 4 outputs each (active-low)

- Logic family: FCT (Fast CMOS, TTL-compatible levels at 5V)

- Supply voltage: 5V nominal (typ. 4.5V–5.5V for FCT logic—verify if critical)

- Package: PDIP-20 (through-hole)

- Markings seen: “210AP”, “9424P” (likely lot/date codes)

Modern uses:

- Bus buffering/isolation for retro CPUs and memory/address/data buses

- Line driving for ribbon-cable / backplane / longer traces on 5V logic systems

- General-purpose inverting buffer in prototypes, test fixtures, and TTL interfacing

Applications:

- Vintage computers, arcade boards, instrumentation, telecom, industrial controllers

- Glue logic / address decoding support circuits

- Signal conditioning and fan-out buffering

Compatibility note:

Often a functional pin-compatible substitute for 74xx240 variants in 5V systems (e.g., 74LS240/74ALS240/74F240/74HC240/74HCT240), but confirm you need the INVERTING “240” function (not “244”), verify OE\ pin behavior (two enables), and ensure your design is truly 5V-tolerant—FCT parts are generally intended for 5V logic.