GE_OEC_9600_C-Arms

16 C-Arm Control
TECHNIQUE PROCESSOR PCB
Assy. #00-876737 - Sch. #00-876735
Assy. #00-877744 - Sch. #00-877742
OVERVIEW
The Technique Processor PCB (see Figures 12 and 13) is responsible for
initializing and controlling the 9600 C-Arm. Application software for the system
resides on the SRAM card located in the on-board solid state disk drive U13.
The Technique Processor PCB plugs into the Motherboard which serves as the
backplane of the card rack (see Figures 1, 9, and 10). The Analog Interface PCB
is a slave to the Technique Processor, carrying out commands received on the
PC bus.
Two versions of this PCB exist and either of these boards may be used in a
system. The difference between the two PCBs, is the communication circuitry
which is discussed in System Communications in this section.
RESET CIRCUITRY AND WATCHDOG TIMER
When power is applied to the Technique Processor, power-on reset circuitry
(U34 & U9) cause the 80C188 microprocessor (U30) to be reset. An external
reset pulse on pin 57 is also generated. This external reset pulse (RST and
*RST via U10) is sent to the real-time clock U29, Dual-Port RAM control PAL
U4, the Control Panel Processor PCB, and to the PIOs located on the Analog
Interface PCB which sets these items to a default state. Switch S2 is used to
manually reset the Technique Processor.
U34 also serves as a “Watchdog Timer” for microprocessor U30. Pin 30 (PCS4)
from the microcprocessor must reset U34 at pin 1 every 1.2 seconds or else U34
will reset the microprocessor via U9 as described above. The purpose of the
“Watchdog” is to interrupt the microprocessor from any unwanted software loops
that may occur.
CPU & BUS INTERFACE
Once reset, microprocessor U30 retrieves instructions from the Boot EPROM
U14 used to initialize the Technique Processor. This is accomplished via the
internal bus interface circuitry composed of address and I/O decoding circuits
U44 - U47 and signal buffer U36. The bus interface circuitry also enables the
Technique Processor to interface with other on-board devices such as SRAM
(U16 - U19), EEPROM (U20), and a serial communications controller U39.