Agilent Technologies 35670-90066 manual Disk Controller Display Controller Frame Memory

Agilent 35670A	Circuit Descriptions
	A7 CPU

All of these assemblies appear as slaves to the IIC Controller. The IIC Controller has access to EEPROM, which allows the CPU assembly to store information such as the analyzer’s serial number. If the CPU assembly is replaced, the EEPROM integrated circuit (U27) on the faulty assembly must be removed and inserted into the new assembly (see ‘’What to do before replacing the CPU assembly’’ in chapter 6). The IIC Controller also has access to a battery backed real-time clock on the A8 Memory assembly.

The IIC bus consists of the following four signal lines:

•SCL (serial clock)

•SDA (serial data)

•SINTn (serial interrupt)

•SINTFPn (serial interrupt for A11 Keyboard Controller assembly)

Disk Controller

Display Controller Frame Memory

Pull-up resistors connect these signals to logic high (all four lines are open collector or open drain). See ‘’A8 Memory,’’ ‘’A11 Keyboard Controller,’’ and ‘’A99 Motherboard’’ in chapter 9 for descriptions of the IIC signals.

Allows the analyzer to store or retrieve data from the internal 3.5-inch flexible A100 Disk Drive assembly. It provides all the control signals necessary to operate the Disk Drive assembly. The Disk Controller performs the following functions:

•Turns on the disk drive motor

•Selects the disk drive head

•Turns on the disk drive LED

•Selects a track on the flexible disk

•Writes or reads serial data to or from the flexible disk

The Disk Controller puts data on the flexible disk in a bit stream that consists of data and clock bits. When data is read from the disk, this circuit separates the data bits from the clock bits, converts the serial data bits to an 8-bit parallel word, and puts the data word on the processor data bus. The operation is reversed when data is written to the disk.

Takes parallel data from the processor data bus and places the data in Frame Memory.

Consists of four 256K  4-bit RAM chips. One bit in Frame Memory corresponds to one pixel on the display. The data in Frame Memory is then sent to the Video Gate Array.

Video Gate Array	Continuously updates the display with the contents of Frame Memory. The Video Gate Array
	also supplies the horizontal and vertical sync signals for the display.
RS-232 Interface	Allows the analyzer to communicate with other devices such as terminals, plotters, or printers
	via Instrument Basic. See Using Instrument Basic with the Agilent 35670A for additional
	information.

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