PMAC-Lite Hardware Reference
2
Introduction
Option 2: Dual Ported RAM
Dual-ported RAM provides a high-speed communications path for bus communications with the host
computer through a bank of shared memory. DPRAM is advised if more than about 100 data items per
second are to be passed between the controller and the host computer in either direction.
Option 2
provides an on-board 8k x 16 bank of dual-ported RAM. The key component on the board is
U46. (Note that for previous versions of the PMAC-Lite, this was a separate board.)
Option 5: CPU & Memory Configurations
The standard PMAC-Lite has a 20-MHz CPU. Options 5A, 5B and 5C are available for applications
requiring more computing power. These options provide faster CPU ICs in U13 and faster SRAM ICs in
U7, U10, and U16. They are only available with flash-memory backup of the SRAM.
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Option 5A
provides a 40 MHz CPU with zero-wait-state SRAM active memory and flash backup.
•
Option 5B
provides a 60 MHz CPU with zero-wait-state SRAM active memory and flash backup.
•
Option 5C
provides an 80 MHz CPU with zero-wait-state SRAM active memory and flash backup.
Option 6: Extended Servo Algorithm
The standard PID servo algorithm with feedforward and notch filter is suitable for most applications.
Systems with difficult dynamics, especially with significant flexibility, may require a more powerful
servo algorithm, such as the Extended Servo Algorithm (ESA).
Option 6
provides firmware in the PMAC-Lite that replaces the standard PID servo algorithm with the
Extended Servo Algorithm. This option provides different firmware in the U5 flash-memory/EPROM IC.
If loaded at the factory, this IC will have a “1” suffix on the labeled and reported version number (e.g.
V1.16D1).
Option 7: Plate Mounting
If the PMAC-Lite is used as an ISA bus expansion board, the standard hardware provides for proper
mounting of the board in the bus. However, if it is not installed in an ISA expansion slot, other
provisions must be made for mounting.
Option 7
provides a mounting plate connected to the PMAC-Lite with standoffs. It is used to install the
PMAC-Lite in standalone applications.
Option 8: High-Accuracy Clock Crystal
The PMAC-Lite has a clock crystal (component Y1) of nominal frequency 19.6608 MHz (~20 MHz).
The standard crystal’s accuracy specification is +/-100 ppm. Long-term velocity accuracy is limited by
the accuracy of the crystal, unless an external time base is used.
Option 8A
provides a nominal 19.6608 MHz crystal with a +/-15 ppm accuracy specification.
Option 9: RS-422 Interface (now standard)
The RS-422 interface now comes standard with the PMAC-Lite in addition to the RS-232 interface.
There is no need to order Option 9L as before.
Option 10: Firmware Version Specification
Normally the PMAC-Lite is provided with the newest released firmware version. A label on the U5
flash-memory/EPROM IC shows the firmware version loaded at the factory.
Option 10
provides for a user-specified firmware version.
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