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8085A Microprocessor IP Verilog Design for Reuse Course Resources

Learning Verilog
For those unfamiliar with the Verilog language, novices, and even seasoned professionals who may need a refresher course on of some of the more arcane constructs of the language, I highly recommend

'Verilog-2001 Quick Reference Guide - Sutherland HDL, Inc.'

by Stuart Sutherland of Sutherland HDL Incorporated. Most of the device vendors also offer courses in Verilog coding. Unless you are designing integrated circuits, ASICs, or sophisticated test benches, the RTL syntax should be sufficient. Even in those cases, RTL is a good starting point.
Most device and synthesis software vendors will include a simulator with their software packages. Many times that simulator is a vendor specific version of ModelSim™. Here are a few of your choices for simulator software:
ModelSim™ by Mentor Graphics - good general purpose simulator for small to medium sized designs. ModelSim™ features a built in waveform viewer. A free student edition is available. I have observed problems with some RAM and ROM constructs. Another issue that I have encountered is that `define statements have a local, rather than global scope. The waveform viewer is a little awkward to use in larger designs when scoping deep into the hierarchy. There is also a tendency to crash when simulating very large designs or using extended simulation intervals.
VCS™ by Synopsis - This is the fastest professional simulator available. Can do min/max timing simulation. Requires code in test bench to enable waveform viewer. Requires an external waveform viewer such as Debussy™ or DAI Signalscan™. Best used on a multiprocessing platform such as a Sun™ server.
Incisive™ By Cadence - I have not used this software; however, its touted features include support for Verilog, System Verilog, VHDL, System C, PSL, and SVA, HDL analysis; and test bench generation and reuse.
Icarus Verilog™ - Free, open-source, Verilog language only, simulator that runs from the command prompt on your PC or server. This is an excellent Verilog 2001 simulator that can easily handle very large designs and extended simulation intervals. Waveform output can be viewed with the open-source GTKWAVE viewer that is included in the download package. The caveat I have noticed is that Icarus Verilog™ does not support `include statements and notes on the same line (this is a non-issue). It also does not support integer functions. We will be using Icarus Verilog™ and GTKWAVE during the lesson modules.

The major device vendors include synthesis within their design software. This software is usually optimized for that vendor's devices. External synthesizers are useful when the vendor's software does not directly support some constructs, such as reusable RAM, ROM, etc. which must be translated into EDIF files before use by the vendor's software; when certain timing constraints are unavailable or cannot be met by the vendor's software; when tracking down syntax errors that are not obvious or adequately reported within the vendor's software; when creating generic functions in EDIF for a range of applications; or when the vendor's software does not include synthesis from Verilog. Potential drawbacks to using an external synthesis tool abound however. Most third party synthesis tools use library modules, written by someone else, that may affect fitting or timing, become outdated, or may not be the most efficient use of device resources. Visual Verilog synthesizers are an especially bad choice, as the subsequent sustainment engineers must have access to the original synthesis software version and libraries for continuing maintenance.

The only synthesis software I can recommend at this time is Synplify PRO™ from Synopsis

Major Device Vendors
There are some major programmable logic vendors on the market today. This list is not intended to exclude smaller vendors or present complete product offerings.
MicroSemi - Manufacturer of anti-fuse based devices, non-volatile FPGAs, and radiation tolerant programmable logic. Produces both CPLDs and FPGAs. Also a supplier of intellectual properties.
ALTERA - An early player in the PLD market. Produces both CPLDs and FPGAs. Also a supplier of intellectual properties. New generation of CPLDs can fit extended functions such as microprocessors.
LATTICE SEMICONDUCTOR - One of the original companies in the PLD market. Produces PALs, GALs, CPLDs, FPGAs, power management, and digital crosspoints. Also a supplier of intellectual properties.
XILINX - The inventor of the FPGA. Some families are military accepted. Produces both CPLDs and FPGAs. Also a supplier of intellectual properties.
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Donald Gerard Polak
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