The **7140LA55PG** is a high-speed, low-power **Dual-Port Static RAM (SRAM)** integrated circuit. It is designed to allow two independent processors or buses to access the same memory space simultaneously without interference, making it ideal for communication between CPUs or as a buffer for data processing. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Memory Capacity** | 8K (1024 x 8-bit) | | **Access Time** | 55 ns (Nanoseconds) | | **Interface** | Parallel (Dual-Port) | | **Technology** | CMOS (Low Power) | | **Package Type** | CPGA-48 (Ceramic Pin Grid Array) | | **Voltage Supply** | 5.0V ± 10% | | **Operating Current** | 160 mA (Active), 5 mA (Standby) | --- ### 2. Functional Description The device provides two separate ports (Left and Right) with independent control, address, and I/O pins. This allows for: * **Asynchronous Operation:** The two ports can operate at different speeds. * **Busy Logic:** It includes hardware "Busy" flags to prevent data contention if both ports try to write to the same memory location at the exact same time. * **Interrupt Logic:** It features "Mailbox" interrupt capabilities to signal between processors that data has been updated. --- ### 3. Pinout and Internal Logic The **CPGA-48** package is a high-reliability ceramic housing often used in industrial or legacy computing environments. Key pin groupings include: * **A0L - A9L / A0R - A9R:** Address inputs for Left and Right ports. * **I/O0L - I/O7L / I/O0R - I/O7R:** Data Input/Output lines. * **CE (Chip Enable):** Enables the specific port. * **OE (Output Enable):** Controls the data output buffers. * **R/W (Read/Write):** Determines the direction of data flow. * **BUSY:** Output signal indicating a port access conflict. --- ### 4. Common Applications Due to its dual-port nature, this chip is typically found in: 1. **Shared Memory Systems:** Connecting two different microcontrollers. 2. **Digital Signal Processing (DSP):** Buffering data between a sensor and a processor. 3. **Communication Controllers:** Acting as a bridge between a local CPU and a network interface. 4. **Legacy Industrial Equipment:** Often used in older PLC (Programmable Logic Controller) boards. --- ### 5. Part Number Breakdown * **7140:** Basic part number for a 1K x 8 Dual-Port RAM. * **L / LA:** Low Power version. * **55:** Speed rating (55ns access time). * **PG:** Package identifier (Ceramic Pin Grid Array). ---