diff --git a/README.md b/README.md index c6be7ac40..790e5b17e 100644 --- a/README.md +++ b/README.md @@ -106,7 +106,7 @@ If you are familiar with Logisim you will recognize the wire color scheme. Logisim is a excellent and proven tool for teaching purposes, that has been actively developed until 2011. In 2013 Carl Burch has started the development of a new simulator called [Toves](http://www.toves.org/). In his [blog](http://www.toves.org/blog/) he explained why he decided to develop a new simulator instead of improving Logisim. -In short: There are weaknesses in Logisims architecture which are too difficult to overcome. +In short: In his opinion, there are weaknesses in Logisim's architecture that are too difficult to overcome. Unfortunately, the development of Toves was discontinued at a very early stage. In 2014, Carl Burch finally [discontinued](http://www.cburch.com/logisim/retire-note.html) the development of @@ -121,7 +121,7 @@ Logisim. Since Logisim was released as open source, there are a number of forks But as far as I know, these projects do not work on solving the architectural difficulties. They are more about adding features and fixing bugs. In [Logisim-Evolution](https://github.com/reds-heig/logisim-evolution), -for example, a VHDL/Verilog export was added. +for example, a VHDL/Verilog export and a really nice FPGA board integration was added. So I also decided to implement a new simulator completely from scratch and started the implementation of Digital in march 2016. In the meantime a development level has been reached which is comparable to Logisim. @@ -224,16 +224,17 @@ D flip-flops or JK flip-flops, including the generation of the state transition Note, however, that a flip-flop build of combinatorial gates is not recognized as such. The analysis of sequential circuits only works with purely combinatorial logic combined with the build-in D or JK flip-flops. -After you have created the truth table or state transition table you can create a JEDEC file for a +Once a truth table or state transition table has been created, a JEDEC file can be exported for a [GAL16v8](http://www.atmel.com/devices/ATF16V8C.aspx) or a [GAL22v10](http://www.atmel.com/devices/ATF22V10C.aspx). -After that you can simply flash this file to the appropriate GAL and test the circuit on a bred board. +After that, this file can be flashed onto a appropriate GAL. As mentioned above these GALs are quite old but with 8/10 macro-cells sufficient for beginners exercises. -If more macro-cells are required, see the PDF documentation that is included in the distribution for details -on how to set up Digital to support the [ATF1502](http://www.microchip.com/wwwproducts/en/ATF1502AS) and -[ATF1504](http://www.microchip.com/wwwproducts/en/ATF1504AS) which offer 32/64 macro-cells and In System Programming. +If more macro-cells are required, see the PDF documentation for details on how to set up Digital to support the +[ATF1502](http://www.microchip.com/wwwproducts/en/ATF1502AS) and +[ATF1504](http://www.microchip.com/wwwproducts/en/ATF1504AS) CPLDs which offer 32/64 macro-cells and In System Programming. It is also possible to export a circuit to VHDL or Verilog to run it on an FPGA. -But the HDL synthesis is a bit time-consuming and in my opinion slows down the workflow in a -lab exercise too much, especially if only very simple circuits are used. +But the necessary HDL synthesis is sometimes a bit time-consuming and in my experience slows down the workflow in a +lab exercise too much, especially if only simple circuits are required and the students change the circuit +over and over again. ## How do I get set up? ##