HP 16500A Service Manual page 72

System Overview Theory
The HP 16500A is the mainframe for the Logic
Analysis System. The mainframe components
include the following:
Microprocessor Board
Mother Board
Front and Rear Disk Drives
Color Module
Front Panel Board
Power Supply
The microprocessor board contains all the
interface circuitry for managing data flow between
the mainframe components and the optional
boards. The microprocessor used is a
Motorola 68000.
Located on the mother board are the intermodule
bus and the fan speed control circuit. The mother
board consists of seven card slots: five are used
for the optional acquisition and stimulus boards,
one for the microprocessor board and one for the
power supply. The only active components on the
mother board are for the fan speed control circuit.
The heat sensing thermistor for the fan speed
control circuit is located on the microprocessor
board.
The front and rear disk drives use 3.5-inch,
double-sided, double-density disks. All of the disk
drive control circuitry is located on the
microprocessor board.
To avoid the loss of your data, do not use
high-density disks in the HP 16500A.
The color module display is an eight-plane color
system. Each plane has a resolution of 576 pixels
by 368 lines. The display is non-interlacing and is
refreshed every 1/60 of a second (not
synchronized to the ac line). The horizontal and
vertical sync signals are generated by the CRT
controller located on the microprocessor board.
Color information for the display is generated on
the microprocessor board. The display RAM and
the color palette are also located on the
microprocessor board.
HP 16500A/16501A - Service
The front-panel board is based on the
Hewlett-Packard Human Interface Link (HP-HIL)
and consists of the touchscreen system, the
front-panel control knob, the optional mouse, and
the optional keyboard. All of the touchscreen and
knob circuitry of the HP-HIL is located on the
front-panel board and the controller for the link is
located on the microprocessor board.
The power supply provides the following regulated
voltages:
12.0 Vdc +5.0 Vdc
+12.0 Vdc 5.2 Vdc
+120 Vdc
The +120.0 V supply is used only by the color
module. Current limiting, overvoltage protection
and thermal shutdown are provided for all supplies.
The HP 16501A is the expansion frame for the
Logic Analysis System. The expansion frame
components include the following:
Expansion Interface Board
Mainframe Interface Board (inserts into the
HP 16500A)
Interface Cable
Mother Board
Power Supply
The HP 16501A is an extension of the backplane
of the HP 16500A mainframe. After you turn on
the mainframe, the HP 16500A microprocessor
board looks for a mainframe interface board in any
one of its five card slot. If it is present and if the
interface cable connects the two frames, the
microprocessor board establishes a link between
the backplanes of the two frames, which then are
displayed as a nine slot system.
The HP 16501A power supply is identical to the
HP 16500A power supply. When power is applied
to the HP 16500A, a relay allows the power supply
in the HP 16501A to turn on. An LED on the
front-panel indicates that the expansion frame has
turned on.
+3.5 Vdc
3.25 Vdc
6-3