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  OrCAD Programmable Logic Design Tools 386+ Version 1.10 Notes
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This file contains information originally distributed with 
PLD 386+ V1.10 that is still relevant for PLD 386+ V2.00 users.

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Miscellaneous technical notes about PLD 386+ V1.10

1.  PEEL Devices - Product term-steering

PLD 386+ implements a form of product term-steering with PEEL devices
that can potentially allow an equation with 57 or more product terms
(depending on the specific PEEL device used) to fit into a single device.
See DEVICES.TXT for more information.

2.  Automatic signal pairing by the logic compiler

AUTOPAIRING is now available in PLD 386+. Now, unless pairing is user specified,
PLD 386+ will automatically pair the signals which can be paired.  See the 
sample file called PAIRING.PLD for an example of the new AUTOPAIRING feature.

3.  PLD Tool Set Configuration

When the logic compiler runs, it looks for the configuration file PLD.BCF. It
first looks in the current design (working directory).  If it doesn't find
PLD.BCF there, PLD builds a path by getting the environmental variable stored
as ORCADPROJ and adding "TEMPLATE\" to it, and then looks for the
configuration file there.  If the configuration file isn't there, then
PLD 386+ uses its built-in default settings.  The file  SWITCHES.TXT contains
a list of defaults.  

4.  User-definable Schematic Symbols

Schematic symbols in PLD 386+ are user-definable. PLD 386+ symbol definitions are 
stored in the file, SYMBOLS.SRC, which is found in the library directory.  
New definitions can be added to the file or existing ones modified.  Before 
and after making any changes to the file, be sure to make a backup, 
otherwise you risk losing your changes if the file is overwritten (such as 
when you installed an updated version of PLD 386+). For more information 
about how to build symbols, see the file SYMBOLS.SRC.  

5.  22V10, 22VP10, 26V12, and PEEL devices - Synchronous Preset

When the synchronous preset term is active it sets all registers.  PLD 386+
scans all the registered equations looking for a common product term.  If one
is found, it is factored from the equation and moved to the synchronous preset
product term.  If this feature is not desired with the 22V10, use the PAL22V10X.

6.  22V10, 22VP10, 26V12, and PEEL devices - Asynchronous Reset

When the asynchronous reset term is active it clears all registers.  This term 
is programmable through the dff() or tff() hardware functions and register
schematic symbols.  Note that the reset term is common for all registers in the
22V10. If this feature is not desired with the 22V10, use the PAL22V10X.

7. RA and EPLD devices - Reset and Preset

PLD 386+ includes keywords that control how RA and EPLD devices behave when
a reset or preset is applied to a register that is defined to use the opposite
polarity.  These new keywords are "Register clear" and "Register set".  By
default, the RA and EP devices are active low. For more information about the
new keywords, see the file DEVICES.TXT.

8. EPLD Devices - Miser bits

Set miser bits to 1 for EPLD devices. The default state of these bits is 0.
If the design fails to program these bits, unpredictable operation may result.
Use the property keyword below to ensure that the miser bits are programmed:

   | Property: "Miser:1"

9. RA devices - Output Enable

Test Logic interprets the output enable term as if it were the only enabling term
on RA devices.  Since the RA devices use a product term ANDed with an
external pin (13 on a 20R10 and 11 on a 16RA8), the external pin MUST be
enabled to generate valid test vectors.  If this pin is not specified in the
logic design, then by default Test Logic will enable this pin.

10. EP310 - Array Feedback

The EP310 supports pin, register feedback, and array feedback.  PLD 386+
supports this feature with the property keyword:

   | Property: "Array Feedback", Q0

If this feature is used, the test vectors generated by Test Logic may not be
correct because the logic simulator does not take the array feedback into account.

11. How to specify signal types in OHDL

If you have questions about how the "in", "out", and "io" keywords apply to
specific devices, consult the DEVICES.TXT file, read its introductory
comments, and keep it handy in a notebook for reference.


As new device tables are developed, they are posted on the OrCAD
electronic bulletin board, which operates 24 hours a day.  Other notes and
information about OrCAD/PLD 386+ and the rest of the OrCAD products are also
available there.  The file BBS.TXT in the directory \ORCADESP\PLD
contains the latest information on the bulletin board and how to access it.

If you have any questions regarding this product, contact OrCAD Technical
Support at (503) 671-9400 (Monday-Friday, 6 AM to 4 PM pacific time).

Thanks for your support,  

OrCAD
