The Microchip/Microsemi/Symmetricom 86-8000 XLi CPU Board is the processing core of the XLi Time and Frequency System, delivering precision timing and synchronization intelligence for demanding applications. Built on a Modified Harvard architecture with 16-bit data path and 24-bit instructions, this board executes C-compiler-optimized code primarily on 1-word/1-cycle operations. It addresses up to 4M instruction words of program memory and 64 Kbytes of data memory, supported by sixteen 16-bit general-purpose registers and flexible indirect addressing modes.
The board achieves UTC accuracy better than 30 nanoseconds RMS and frequency accuracy better than 1×10⁻¹² when paired with a GPS receiver. It accepts Primary and Secondary Reference Inputs including GPS, IRIG A/B time code, IEEE 1344, NASA36 (AM or DC formats), and 1PPS signals. An auxiliary reference input enables lock to external cesium for enhanced holdover performance. Standard outputs include 1PPS (20 µs ±1µs pulse width, TTL levels into 50Ω), programmable pulse rates, and open-collector alarm output.
Technical Specifications
• CPU: Modified Harvard architecture, 16-bit data path, 24-bit instructions
• Memory: 4M instruction words (program), 64 Kbytes data memory
• Registers: Sixteen 16-bit general-purpose registers
• Instruction Set: C compiler optimized; primarily 1-word/1-cycle execution
• Operating System: vxWorks
• Network Interface: 10/100 Base-T Ethernet (RJ-45)
• Serial Ports: RS-232/422 (Telnet, CLI support)
• Protocols: HTTP, Telnet, SNMP (enterprise MIB), FTP, optional NTP/SNTP
• Management: HTML web interface, plug-and-play configuration, remote firmware updates
• UTC Accuracy: Better than 30 nanoseconds RMS (with GPS)
• Frequency Accuracy: Better than 1×10⁻¹² (with GPS)
• 1PPS Output: 20 µs ±1µs pulse width, TTL into 50Ω
• Time Code Support: IRIG A/B, IEEE 1344, NASA36 (AM and DCLS formats)
• Stratum 1 NTP Server: Available with NTS option
– Key Features
• Modular architecture supporting up to ten option modules for customization
• Flexible reference input configuration (GPS, time code, 1PPS, external cesium)
• Programmable output pulse rates and alarm signaling
• Remote management via web interface, Telnet, and SNMP
– Typical Applications
Precision synchronization and timing distribution in telecommunications, power grid monitoring, financial networks, and scientific research environments requiring holdover stability and UTC traceability.
– Compatibility & Integration
Designed as the control element for the XLi Time and Frequency System platform, with plug-and-play module recognition and extensible architecture.
