James Stanley

Posts tagged 'cpu'

Front panels for SCAMP »

Sun 28 February 2021

I've put together the memory card for the SCAMP CPU, including the front panel with LEDs to show the bus contents and address register. Read more »

The SCAMP kernel »

Sat 27 February 2021

You might think it's a bit early to be working on an operating system, given that I don't have a CPU to run it on. Maybe you're right. But working on software is easy and working on hardware is time-consuming, so here we are. Read more »

A compiler for SCAMP, and machine code profiling »

Fri 19 February 2021

I've been working on a compiler for the SCAMP CPU. It compiles a language I'm calling "SLANG" (which just stands for "SCAMP Language" pending a better backronym) into SCAMP assembly language. Read more »

My second attempt at milling a PCB »

Mon 15 February 2021

The day after my first attempt at milling a PCB, my new tooling arrived (a 1 mm drill bit and a 10° engraving tool), so I had another go at making a PCB. Read more »

My first attempt at milling a PCB »

Fri 12 February 2021

I'm going to get most of the PCBs for SCAMP made by JLCPCB, but I'd like to try to mill the backplane on the CNC machine because it is both large (expensive at JLCPCB) and simple (single-sided, no vias, easy to make). Yesterday some small pieces of copper-clad board arrived and today I had a first attempt to see what would go wrong. Read more »

Making a start on the SCAMP ALU cards »

Sat 6 February 2021

I'm pretty happy with the CPU design now and am ready to proceed to making it physically exist. I am still finding the odd microcode bug, but these can be fixed at any time. I'm at least not finding any architecture-level bugs. Read more »

Designing the instruction set for my TTL CPU »

Sun 31 January 2021

I (believe I) am making good progress on designing the TTL CPU. Most of the actual CPU design is relatively stable now, and bug discoveries in the hardware design are infrequent, so now I get to move up a level and work on the instruction set. After that, it's just the bootloader, operating system, and application software. Oh, and the small matter of the physical hardware assembly... Read more »

Progress on my TTL CPU design »

Sun 24 January 2021

I want to make a CPU out of physical 74xx TTL chips. I have now implemented most of the parts using a subset of Verilog that maps directly to TTL chips, and I wanted to write a bit about the design. Read more »

Adventures in CPU design »

Fri 15 January 2021

On Graham's recommendation, I recently bought an iCE40 FPGA and have been learning a bit about how to use it. The iCE40 is good to get because there is good open-source tooling that supports it. I was originally going to get the iCEstick evaluation board, but there are other alternatives available more cheaply and with more logic elements. I ended up getting an iceFun and have found it to be quite easy to use. The example projects are helpful. Read more »