My CPU

Fun CPU is a seven bit homebrew processor with unique, unconventional design to natively support functional programming in machine language. FunCPU employs a tagged architecture, but does not have registers, of which contents are exposed to the programmer. Sure, it has some internal registers, but…

The picture below depicts the overall architecture of the FunCPU. It employs a 8 bit wide databus and a 9 bit wide address bus. Please recall, that although the databus is 8 bits wide, due to the nature of the tagged architecture only 7 out of 8 bits can be used externally (i.e. by the program), and…

The ALU module is very simple and straightforward. It is mounted together with the control board encoding logic on a single board. It performs a simple addition operation on the two operands as described in the following table. The two selector bits define the two input sources. ALU…

Ok, here is a photo of the real control panel. It is a little bit different from the original design. It does not look that  spectacular, but has decent functionality.  The upper section includes 8 LEDs and 8 toggle switches. These are used for data entry as indicated by the label in between.…

It is high time I had gone to look for a suitable box to be the case of the FunCPU. I have decided on the one below. It is quite ugly and girlish actually, but it was the cheapest option. At least this will be the choice for CPU-case of my first attempt to build the CPU.  I expect to implement…

The FunCPU (in its current version) supports only numerical computation, more precisely, operations with integers. Functional languages, such as Lisp, Clean, etc. come with a richer set of data types and also have some kind of type construct capability. For example, Lisp as its name suggests mainly…

It is high time we turned our attention to a complex mathematical problem. Namely, how FunCPU computes:1+1=? Please recall that the definition of "add" is stored at 00 (referenced by 81) is as follows:add(x,y):=   FD 7F 7E FC 81 7E FE 7F FF The following is an extract from the FunCPU…

Let us have a look at some elementary functions and predicates to have a better look and feel how FunCPU works. The definitions of these objects will be suppmented with their assembly code counterparts written directly in FunCPU machine code. In the subsequent section, the following encoding is…