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6 page 
PC COMMUNICATION Copyright Semtech, 1997-2001 DOC5-FJL-DS-106 www.semtech.com 6 The UR5HCFJL implements all the standard functions of communication with a BIOS- compatible PC/XT or AT/PS/2 host system. Two lines, KC and KD, provide bi-directional clock and data signals. In addition, the UR5HCFJL supports all commands from and to the system, as described in the IBM Technical Reference Manuals. The following table shows the commands that the system may send and their values in hex. Command Hex Value Set/Reset Status ED Indicators Echo EE Invalid Command EF Select Alternate F0 Scan Codes Invalid Command F1 Read ID F2 Set Typematic F3 Rate/Delay Enable F4 Default Disable F5 Set Default F6 Set All Keys Typematic F7 Make/Break F8 Make F9 Typematic/Make/Break FA Set Key Type Typematic FB Make/Break FC Make FD Resend FE Reset FF Table 2: Keyboard Commands from the System (AT/PS/2 protocol) These commands are supported in the AT/PS/2 protocol and can be sent to the keyboard at any time. The following table shows the commands that the keyboard may send to the system. Command Hex Value Key Detection 00* Error/Overrun Keyboard ID 83AB BAT Completion Code AA BAT Failure Code FC Echo EE Acknowledge (Ack) FA Resend FE Key Detection Error/Overrun FF** *Code Sets 2 and 3 **Code Set 1 Table 3: Keyboard Commands to the System (AT/PS/2 protocol) When an external keyboard is connected, commands from the system will also be directed to the external keyboard. Presence or absence of an external device will not effect the normal operation of the GreenCoderTM. |
