HP 1660CS-Series User Manual page 274

The Analyzer Hardware
HP 1660CS-series analyzer theory
CPU board
The microprocessor is a Motorola 68EC020 running at 25 MHz. The
microprocessor controls all of the functions of the logic analyzer including
processing and storing data, displaying data, and configuring the acquisition
ICs to obtain and store data.
System memory
The system memory is made up of both read-only memory (ROM) and
random access memory (RAM). Two types of ROM are used. A single 128Kx8
EPROM is used as a boot ROM, and four 512Kx8 Flash ROMs are configured
to provide a 512Kx32 Flash ROM space. One SIMM socket supports 2-MB,
4-MB, or 8-MB SIMMs.
On power-up, instructions in the boot ROM command the instrument to
execute its boot routine. The boot routine includes power-up operation
verification of the instrument subsystems and entering the operating system.
The CPU searches for the operating system on flash ROM. Then, if the
operating system is in flash ROM, the instrument will be initialized with the
default configuration and await front panel instructions from you. If the
operating system is not in flash ROM, the CPU accesses the disk drives to see
if the operating system is on the disks.
The DRAM stores the instrument configuration, acquired data to be
processed, and any inverse assembler loaded in the instrument by the user.
Keypad and knob interface
The front panel keypad is scanned directly from the microprocessor address
bus during the video blanking cycle of the CRT. When a front panel key is
pressed the associated address bits are fed to the data bus through the
pressed key and read by the microprocessor.
The rotary pulse generator (RPG) knob has its own interface. Pulses and
direction of rotation information are directed to the RPG interface. The
microprocessor then reads and interprets the RPG signals and performs the
desired tasks.
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