Product Overview
Intel P8242 UPI-42 Keyboard Controller IC — AT-Bus Gate A20, 40-Pin PDIP, 5V
Condition
Single unit available. Unused NOS — recovered from legacy electronics supply chain stock. Pins are straight and show no oxidation. Evaluation: Visual inspection only. Function testing not performed.
Ships same business day from Idaho. Packed carefully.
Product Overview
Intel P8242 is a pre-programmed 8-bit UPI-42 Universal Peripheral Interface microcontroller designed as the AT-bus keyboard controller. It translates keyboard signals into data the host processor can read and controls the Gate A20 line — the hardware signal required to access memory above 1MB. Found on IBM PC/AT (80286) motherboards and AT-architecture 80386 boards. Packaged in a 40-pin plastic DIP for direct socketed installation.
Key Features
- Architecture: UPI-42 Universal Peripheral Interface, 8-bit microcomputer
- Package: 40-Pin PDIP (Plastic Dual In-line Package)
- Supply Voltage: 5V
- Clock Speed: Up to 12MHz
- Function: AT keyboard interface and Gate A20 line control
- Interface: AT/PS-2 keyboard port via AT-bus motherboard socket
- Plastic "P" prefix package — distinct from ceramic "D" variants
Applications
- Replacement keyboard controller on IBM PC/AT and AT-compatible 286 motherboards
- 80386 systems using AT-bus architecture
- Resolving keyboard error or Gate A20 error at POST on legacy systems
- CNC controllers and industrial hardware running on AT-class boards
- Vintage PC restoration and retro computing builds
Frequently Asked Questions
Is this compatible with IBM PC/XT or 8041-based motherboards?
No. The P8242 is designed for AT-bus architecture. The original IBM PC/XT uses the 8041 with a different keyboard protocol. These chips are not electrically interchangeable.
Will this work with my 286 or 386 AT-compatible motherboard?
Yes, for the large majority of AT-clone motherboards. Generic P8242 chips are broadly compatible across AT-architecture 286 and early 386 boards. If your board requires a firmware-specific version matched to a particular BIOS vendor (AMI, Phoenix, IBM), verify the original chip's markings before replacing.
What is the Gate A20 function and why does it matter?
Gate A20 is a hardware line the P8242 controls to enable access to memory above the 1MB boundary. If this line fails, DOS and early Windows environments will exhibit high-memory errors or fail to boot properly — a common symptom of a failing keyboard controller chip.
Are the pins in good condition?
Pins are straight with no visible oxidation. Evaluation: Visual inspection only. Function testing not performed — verify against datasheet before use.
The "P" prefix confirms plastic packaging. Ceramic "D" variants carry different thermal ratings but are functionally equivalent in most AT sockets. Check your socket clearance if packaging type matters for your application.
