Hello,

I am new to this forum. I am F4HDK, a hobbyist from France.
I would like to present my last project that I have just completed and documented here :
https://hackaday.io/project/18206-a2z-computer

Video: https://www.youtube.com/watch?v=76hnOPgyzr0

It is called “A2Z computer”. It is a computer made from scratch. Every part is invented, designed, and built/coded by me. I have not copied/ported existing architectures or code or software library. This is a didactic project, the goal is to learn about every part of a simple computer, from low level hardware to software, compiler.

Hardware (programmed in Verilog on a small FPGA) :

• Custom CPU RISC 16bits (address bus 24 bits), with a custom instruction set, with Integer ALU, without interrupt capabilities
• SRAM 2MB
• VGA with 2 parts :
  1) Graphics 640 x 480 x 60Hz ; 256 colors; double buffering; video RAM shared with CPU
  2) Text overlaid (over graphic) 80 x 30
• PS/2 keyboard interface
• Serial port (interface with development PC)
• SPI interface with a 16MB Flash chip

Software:

• Custom basic language, with a homemade compiler
• Assembler
• Basic file system, and (very) simple OS
• A text editor
• Image viewer and map viewer
• A car game like MicroMachines

Do not hesitate to give me feedback, or ask any question!




F4HDK

Welcome! Very impressive!

Fantastic job, well done - and welcome!

I'll read through your project logs and have a look at your sources - should be very interesting.

Allo. Quite an accomplishment.

Amazing work! And welcome to the forum.

Congratulations.

Do you plan on making any upgrades?

Is this computer scalable?

Thank you all for your feedback.

Currently, no, I consider that this project is finished.
I have lots of other projects in my "to do" list.

So unless someone wants to really use this project (as an educationnal material for example), I will not work anymore on it.
If someone is really interested, I will probably change my opinion.


It depends what you mean by "scalable".

* RAM and Flash : that's the easy part. It would be very easy to add SRAM and Flash. The computer has 24 address lines, and can address 16MB or RAM (minus peripherals). I could easilly change the memory module to a module on a PCB with SRAM, exactly like yours (http://wilsonminesco.com/)

* peripherals : The easiest way to add peripherals would be to use the SPI bus (currently used only for Flash Memory). Adding a Wiznet Chip for Ethernet interface for example. There is still space on the veroboard for that.

* Software : currently, this CPU is compatible with... nothing. That's good for educational purpose : I had to code everything from scratch. "Learning by doing" is the main goal of this project.
But if you want to add a new functionnality, you need to code it!
So a major improvement for scalability would be to retarget an existing C COMPILER. That is necessary if I want to port existing code. A sofware enthousiast has already thought about it. And he has proved that the core of this CPU lacks too many things : indirect addressing, some operations in ALU, etc...

* CPU : so if I want to make this CPU really usable, and really scalable, the first thing to do is to make modifications inside the CPU, and add vital features : indirect addressing, ALU operations, interrupts, etc...

F4HDK.