Intel PC28F128P30T85A: A Comprehensive Technical Overview of a High-Density 128-Megabit Parallel NOR Flash Memory
The Intel PC28F128P30T85A stands as a significant component in the landscape of non-volatile memory solutions, representing a high-performance, high-density parallel NOR Flash memory device. Engineered for applications demanding robust execution-in-place (XIP) capabilities, reliability, and fast read access, this 128-megabit chip has been a cornerstone in embedded systems, networking equipment, telecommunications infrastructure, and industrial control systems.
Architectural Foundation and Core Features
At its core, the PC28F128P30T85A is organized as 16 megabytes of 8 bits each (16M x 8) or 8 megabytes of 16 bits each (8M x 16), providing design flexibility for different system bus widths. This symmetrical sector architecture is pivotal for efficient memory management. The device features uniform 128-KB sectors, each individually erasable, which allows for fine-grained control over memory space. This is critical for storing application code, boot code, and configuration data that require frequent updates without affecting the entire memory array.
A key attribute of this memory family is its asynchronous page mode operation. By accessing a "page" of memory (typically 4 or 8 words) in a burst, it significantly reduces effective read access times. While the initial access might be 85ns (as denoted by the '85' in its suffix), subsequent accesses within the same page can be as fast as 25ns, dramatically boosting system throughput.
Performance and Voltage Specifications
The device operates on a versatile voltage supply. The core logic operates at a low 1.8V VCC for reduced power consumption, while the I/O buffers can be powered by either 1.8V or 3.0V (VCCQ), enabling easy interfacing with both legacy and modern low-voltage processors and system logic without the need for level shifters.
Its performance is characterized by a fast 85ns maximum initial access time and a high-speed 54MHz burst mode frequency. This combination makes it suitable for high-performance systems where the processor can fetch code directly from the flash memory without first shadowing it into RAM.
Reliability and Endurance
Built for mission-critical environments, the PC28F128P30T85A boasts exceptional reliability metrics. It supports a minimum of 100,000 program/erase cycles per sector, ensuring long-term data retention and rewrite capability. Data integrity is further guaranteed for up to 20 years, a vital feature for systems with extended operational lifespans.
Advanced Control and Protection Mechanisms
Intel equipped this memory with a sophisticated command set for its operation, requiring specific write sequences to initiate programming, erase, or configuration functions. This protects against accidental data corruption from errant software execution or system noise.
The chip incorporates several hardware and software protection features:
Absolute Protection: A dedicated `WP` (Write Protect) pin allows the system to instantly hardware-lock the bottom or top sectors, safeguarding critical boot code.
Password Protection: A 64-bit password can be set to prevent unauthorized program or erase commands, adding a layer of security.
Persistent Sector Protection: Individual sectors can be locked or unlocked via software commands, providing flexible memory management.
Typical Applications
The combination of density, speed, and reliability made the PC28F128P30T85A ideal for a wide range of applications:
Networking Routers and Switches: Storing firmware, boot code, and configuration data.
Telecommunications Base Stations: Critical for system initialization and operation.
Industrial Automation and Control Systems: Where reliability and long-term data retention are paramount.
Automotive Systems: In-vehicle infotainment and engine control units (although newer serial flash often supersedes it in modern designs).
Legacy Computing and Embedded Systems: Serving as a reliable BIOS or firmware storage solution.
ICGOOODFIND
The Intel PC28F128P30T85A exemplifies the peak of high-density parallel NOR Flash technology. Its blend of high-speed asynchronous page-mode reading, flexible voltage operation, and robust hardware-based security features solidified its role as a trusted, high-performance solution for a generation of embedded systems requiring reliable, execute-in-place memory. While newer serial interface memories now dominate for their smaller footprint, this device remains a benchmark for performance and reliability in its class.
Keywords:
1. Parallel NOR Flash
2. Execute-in-Place (XIP)
3. Asynchronous Page Mode
4. Sector Erase Architecture
5. Hardware Write Protection
