Experimental Hardware
With the design of the Tiny CPU core more or less finished, I’ve started thinking about how to build a small computer around it. My goal is to create a simple machine with a keyboard input, a 4-line LCD output,…
Month April 2010
Variable Size Instructions
My analysis of the advantages of fixed-size instructions proved to be badly flawed. The improvements I saw when switching to a 16-bit fixed instruction size were not what I originally thought: the size and speed gains came from the reduction…
Tiny CPU Architecture
As promised, here’s the Tiny CPU architecture diagram. SP is the stack pointer, and is 6 bits, providing a 64-entry stack. EA is the effective address, used for data load/store from absolute or computed addresses. PC is the program counter.…
Tiny Asm
I’ve finished writing the Tiny CPU assembler, and it works. It took about four hours across two nights to get something with basic functionality. The curious can take a look at the assembler source code for details. I don’t have…
Fixed Size Instructions
I’ve finished my experiment with fixed-size instructions for Tiny CPU, and the results are encouraging. I did a straightforward conversion to a 16-bit instruction size, with the opcode in the upper 6 bits and the address (if any) in the…
Tiny CPU
I’ve got a working CPU! You can grab the Verilog source and a testbench. The instruction set and addressing modes are as I described them in my previous post, except that I shrank the stack pointer to 6 bits (64…
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