CDP1851E

Specialized Overview

The CDP1851E is a CMOS programmable two-port I/O interface designed for general-purpose peripheral control. It features 20 programmable I/O lines and operates directly with CDP1800-series microprocessors at maximum clock frequencies. The device supports four operational modes: input, output, bidirectional, and bit-programmable. Port A allows bidirectional configuration with handshaking, while Port B functions as an 8-bit output with handshaking or bit-programmable mode. The E suffix indicates a 40-lead dual-in-line plastic package. The supply voltage range is specified from 4V to 10.5V.

Specialized Feature Summary

• Supports byte-I/O and bit-programmable modes for flexible peripheral interfacing
• Provides independent handshaking control lines (RDY and STROBE) for bus access management
• Allows individual line designation as input or output within each port

Specialized Applications

• Interfacing with printer peripherals
• Connecting keyboard interfaces
• General-purpose microprocessor system communication

Specialized Procurement Notes

Verify the manufacturer origin, as Harris Corporation assets were acquired by Renesas Electronics. Confirm the specific suffix 'E' corresponds to the 40-lead DIP plastic package in official datasheets. Check RoHS compliance status, as original Harris components may not meet modern environmental standards. Ensure compatibility with the target CDP1800-series processor clock speeds.

Specialized Selection Notes

Select the CDP1851E when direct compatibility with CDP1800-series processors is required. Choose this component over standard parallel interfaces if programmable bit-level control or handshaking signals are necessary. Verify that the 4V to 10.5V operating voltage range aligns with the system power supply design constraints.

Specialized Part Context

The CDP1851 belongs to the CDP1800 series of CMOS microcomputer components originally developed by Harris Semiconductor. This series was widely used in embedded systems during the late 1970s and 1980s. The CDP1851 specifically addresses the need for flexible I/O expansion without requiring complex external logic gates.

Specialized Replacement Considerations

Renesas Electronics is the current successor to Harris Semiconductor's microcontroller portfolio. Verify if Renesas offers a direct pin-compatible replacement or updated documentation for legacy support.