Agilent Technologies 01664-97005 External Keyboard Interface, Centronix Interface, Disk Drive

Theory of Operation

The 1664A Logic Analyzer

External Keyboard Interface

Agilent proprietary ICs make up the external keyboard interface. The ICs establish a link with the controller IC on the external keyboard. The keyboard signals are routed through the acquisition circuit board to the CPU board. The microprocessor then reads and interprets the external keyboard and mouse information and performs the desired tasks.

Centronix Interface

The instrument parallel printer interface is compatible with industry standard Centronix protocol. The interface consists of a controller, and drivers/receivers. The controller conditions parallel data from the microprocessor for transmission. At the same time the controller also receives status information for the microprocessor. Data flow, status, and handshaking control are also provided by the controller.

Optional GPIB Interface

The instrument interfaces to GPIB as defined by IEEE Standard 488.2. The interface consists of an GPIB controller and two octal drivers/receivers. The microprocessor routes GPIB data to the controller. The controller then buffers the 8-bit GPIB data bits and generates the bus handshaking signals. The data and handshaking signals are then routed to the GPIB bus through the octal line drivers/receivers. The drivers/receivers provide data and control signal transfer between the bus and controller.

Optional RS-232C Interface

The instrument RS-232C interface is compatible with standard RS-232C protocol. The interface consists of a controller, and drivers/receivers. The controller serializes parallel data from the microprocessor for transmission. At the same time the controller also receives serial data and converts the data to parallel data characters for the microprocessor.

The controller contains a baud rate generator that can be programmed from the logic analyzer front panel for one of eight baud rates. Other RS-232C communications parameters can also be programmed from the logic analyzer front panel.

The drivers/receivers interface the instrument with data communications equipment. Slew rate control is provided on the ICs eliminating the need for external capacitors.

CRT Monitor Assembly

The CRT Monitor Assembly consists of a monochrome CRT and a monitor driver board. The monitor driver board provides the biasing and control signals for the CRT. Pixel information is stored in the display RAM on the CPU board and is routed to the monitor driver board through the acquisition board and the sweep cable.

Disk Drive

The disk drive assembly is a high density disk drive that formats double-sided, double-density or high density disks in LIF or DOS format. A disk drive controller on the CPU board controls the disk drive. Signals are routed directly to the disk drive through the disk drive cable.

Power Supply

A low voltage power supply provides all DC voltages needed to operate the logic analyzer. The power supply also provides the +5 Vdc voltage to the probe cables to power logic analyzer accessories and preprocessors.

Unfiltered voltages of +12 V, -12 V, +5 V, -5.2 V, and +3.5 V are supplied to the acquisition board where they are filtered and distributed to the CPU board, CRT Monitor Assembly, and probe cables.

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