Toolchain update 2

Last time I mentioned that LCC port required updates to the instruction set. Indeed, I decided to give up some instructions in favour of those which seemed to make more sense in view of code generation. I did a major ISA cleanup: I have removed register indirect with register offset addressing modes like in LD ...

New memory & next steps 6

New memory & next steps
I have been unable to spend much time on the project lately, so there is no important milestone to report today. Still, some time ago I soldered the new memory board, implementing the banked model described in this post, and extending the original idea. It worked at the very first attempt, so I have no ...

Yet another instruction set update

Some time ago, when fiddling with my Monitor/OS program I decided to make a few changes to the instruction set. I guess that’s the real flexibility when you build your own CPU – if you don’t like the instruction set, and you suddenly come up with a need for an instruction that is missing, you ...

Assembler and instruction set update 2

I am slowly progressing on my simplistic OS/Monitor development. It is only a little fun, mainly because I do not have a functional simulator (i.e. emulator) of the computer and I have to test every bit of assembly code on real hardware. For that I have to constantly switch from Linux (where my development toolchain ...

New instructions, final test run and Fibonacci

Just a quick summary of what I have been doing over the last few sessionsĀ in the project. New instructions Before I continue with hardware I decided to add a few instructions I should have added a long time ago but somehow never got to it. The instructions are shorter versions of some load/store instructions I ...

Instruction set

I mentioned in my last post that my intention is to design with a two-address instruction set. This means that my instructions will have zero, one or two operands. There is no important reason for this. I am familiar with 6502 (accumulator, one-address) and x86 instruction sets, and I am more used to the latter, ...