Optimal Shop 4 Digit PCI and ISA PC Computer Motherboard Analyzer Tester Diagnostic Debug POST Card External Display PCI ISA 4-Digit PC analyzer.Standard PCI & ISA interface for easy access to your desktop PC.4-Digit display. Frontal 2 digit for current error code & back 2 digit for previous error code. POST (Power On Self Test) card displays error code quickly when booting. Error code table offered makes you know the error details easily. Hexadecimal character display. S1 press button available for multi-function operation.Jumper & cable available for speakers.8 LED indicators available for +3.3V, +5V, +12V, -12V, RESET, FRAME, IRDY & CLK.Dimension: 83mmX90mm.Weight: 40g. Supports 80H, 84H & 300H port and compatible with all mainstream motherboards. Supports code search function. (While testing, press S1 button 1 second to start up search, press S1 half second to start down search till end, then press S1 1 second again to start down search and press S1 half second to search previous error code till end.) Supports motherboard bus speed test. (While down searching, press S1 button 1 second to start bus speed test function.)Supports self-check. (While bus speed testing, press S1 button 1 second to start self-check function, then press S1 half second to repeat and press S1 1 second again to return to analysis status.) Supports AMI, Award, Phoenix & Tandy 300 BIOS.