8051 FAQ


This is the FAQ – Frequently Asked Questions – of Oregano Systems‘ 8051 IP Core. We received a lot of feedback and questions from users all over the world. In order to simply using our free 8051 IP Core we decided to summarize the most frequently heard questions – as well as their answers, of course.

We kindly ask you first to browse through this FAQ list prior contacting our support staff via e-mail.

Is there a license fee for the 8051 IP Core when using it in an industrial project?
No there is no license fee for using the 8051 IP Core in any project.

Where to get the most recent source code of the 8051 IP Core?
You will find the most recent version of the public available 8051 IP Core always at our web site.

What are the requirements for the FPGA target family?
The target FPGA family shall offer sufficient amount of on-chip memory blocks to embed at least all RAMs you connect to the 8051 IP core on-chip. The ROM is very often still implemented externally in a Flash device. Generally spoken it will speed up your design if you keep all memories on chip.
Beside memory blocks one needs sufficient logic resource to implement the 8051 IP core as well as other logic. Usually it does not make sense just to implement a processor in a FPGA. The resources required depend on your parameters you have choosen for the 8051 IP core. For a fist estimate just calculate approx. 3500 LUTs.

There is an error during synthesis when compiling the units mc8051_ram, mc8051_rom etc. stating the the package textio is not found?
You are trying to synthesize our sample simulation models of the memories. This leads of course to these errors. Memories are technology specific and are usually generated by special generator software like Altera’s Megafunction Wizard or Xilinx‘ Core Generator.

Which synthesis tool is recommended?
We strongly encourage to use dedicated FPGA synthesis tools like Mentor’s Leonardo and Precision or Synplicity’s Synplify. For ASIC designs we recommend to use Synopsys‘ DesignCompiler. Generlally the VHDL code of the 8051 IP core is tool independent. I.e. any standard synthesis tool shall be capable to synthesize the VHDL code to your selected target technology.

There are errors when synthesizing the 8051 IP core using FPGA vendor’s synthesis tools?
The FPGA vendor’s synthesis tools (note: not the OEM versions of dedicated synthesis tools but tools developed by FPGA vendors!) are frequently somewhat limited in their functionality compared to dedicated synthesis tools. They often do not support all VHDL constructs or end up larger but slower circuits. There are often requirements that entity and architecture have to be in the same file etc. We generally recommend to use dedicated synthesis tools for synthesizing circuits.

Why does the 8051 IP core require more resources compared to the configurable processors of Altera (Nios) and Xilinx (MicroBlaze)?
The difference is mainly the procesor’s basic architecture. The 8051 processor is a CISC processor while the FPGA vendor’s configurable processors are RISC processors. Additionally these processors have been optimized to be implemented efficiently on their specific target technology.

Do you recommend to start new products using the 8051 IP core?
We recommend to use the 8051 processor whenever the already existing software written for that processor has to be reused. For these projects one may benefit from the SOC integration using our 8051 IP core. For completely new products where also the software development starts from scratch we recommend to use another processor architecture.

You do not get a response to your email to the 8051 support email address?
You have sent a question to our contact mail adress and did not received an answer? There may be several reasons for this. We offer this service free of charge. Thus it may take some days until we are able to answer your questions because we are busy with our commercial projects. Usually you will receive the answer within two days. Frequently, emails to the 8051 support address are infected with some kind of viruses. On the average about one quarter of the emails we receive are infected. Our virus scan deletes all this messages automatically without further notice.