IBM 6400 Series, Maintenance Information Manual

Page: 49 / 422

Engine Controller
49
“Cajun” Bus Interface
The “Cajun” bus interfaces the DC, the EC, and the expansion port. The EC
uses this bus to access DC resources, including the semaphore registers.
(The semaphore registers are the primary communications path between the
EC and DC.)
Ports
The VX ASIC controls the following I/O functions:
•
Interface to an IEEE** 1284 Level 2 host
•
Interface to RS-232E serial host
•
Interface to RS-422 serial host
All the circuitry required for these host types is provided on the CMX board,
except for the drivers themselves, ESD protection, and terminations.
Host I/O Drivers And Termination
Beyond the 030 processor and VX ASIC, additional support circuitry
completes the serial and parallel interfaces. These circuits include:
•
RS-232 drivers and receivers. These circuits use internal charge pumps
to eliminate the need for
±
12V power.
•
RS-422 differential drivers and receivers
•
Parallel port pull up and pull down terminating resistors are DIP-socketed
for easy removal and installation.
All interface ICs and terminations have the following characteristics:
•
Provide ESD protection to 15KV for all inputs.
•
Less than 0.05V common mode ripple, measured at the power and
ground of the interface ICs.
•
Less than 0.02V common mode ripple, measured between chassis
ground and the ground pins of the interface ICs.
•
Greater than 200V/
µ
s slew rate for all outputs.
Engine Controller
The engine controller (EC) consists of four main elements:
•
80C166 Microcontroller
•
128KB 5.0V-only FLASH program memory, organized as 64K x 16 bits.
This memory is not expandable.
•
MECA (Mechanism Engine Control ASIC)
•
Analog drive circuitry
80C166 Microprocessor
The Siemens** SAB 80C166 is a high-integration microcontroller. It has many
features that suit it extremely well to real-time control applications. This