Service manual

Storage and Transmission (Option #A05 0nly)
3-15
Flash1, Flash2
FLASH1 and FLASH2 are 1M x 16 bit flash ROMs. The gate array provides control and
timing functions required to interface these parts to the address and data bus. FLASH1 is
used for non-volatile ECG storage. FLASH2 is provided for expansion memory. It is not
normally present on the Option #A05 printed circuit assembly.
VPROG Power Supply
The VPROG power supply provides a 12V DC programming voltage to FLASH1 and
FLASH2 during erase and write operations. The source for the supply is the cardiograph
printhead supply voltage, which is turned on and off by the software. The VPROG supply
circuit contains a 12V linear regulator that drops the printhead supply voltage to the
required 12 volts for FLASH1 and FLASH2.
Dual UART
The Dual UART (Universal Asynchronous Receiver/Transmitter) contains two
independent UARTs with the following capabilities:
• modem control
• baud rate generator
• 16 byte FIFO (first-in-first-out) buffer
Each UART is used to implement an RS232 port by translating between serial and parallel
data.
18.432 MHz Oscillator
The 18.432 MHz Oscillator provides a clock for the internal functions of the Dual UART.
RS232 Drivers
The RS232 Drivers perform the voltage level translation between TTL logic level signals
from the Dual UART and the +
10 volt RS232 signals.
Serial Port Connectors 1 and 2
These connectors are 9-pin D-subminiature connectors that are located at the back panel
of the cardiograph, and provide access to the two RS232 ports. The serial port marked
RS-232 is used for ECG transmission. The other serial port is reserved for future use.
The #A10 interface board also, provides storage and transmission capability in addition to
the HP StressWriter interface.