Neoarcheon computer

_{Neoarcheon means "The new dawn of ancient times". It comes from "Neo", a prefix for "New", and "Eoarchean", the era in which life began.}

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Summary

1. Aims and challenges
2. Design
   1. Core architecture
   2. Registers and memory map
   3. The instruction set

Aims and challenges

Make a turing complete computer from scratch.

At first every part of the computer will be the "industrial" version :

• The CPU from logic gates.
• The RAM a SRAM chip (UM61256BK-20 from 1993)
• The ROM another chip (D27C010 from 1986 !)

Then the aim is to replace them with made from scratch versions. For the moment only the RAM is meant to be replaced with homemade magnetic core RAM.

NOT ANY SORTS OF AI WILL BE USED IN THIS PROJECT.

Why ?

People in the 70s got someone on the moon with their brain, and made him come back. AI is useful for medicine, protein research or other deep research subjects. I do not need a LLM to understand and make a computer.

Design

The design is inspired of great people hard work :

• Ben Eater's 8 bits breadboard computer
• Mattbatwings's Minecraft computer tutorial

The core architecture is inspired of the legendary Intel's MCS-51 microcontroller series.

The computer is in 8 bits. The target frequency of the processor is 10mHz

Core architecture

_{Made with Drawio.}

Registers and memory map

Name	Long Name	Description
IR	Instruction Register	Running instruction storage.
A	A Register	ALU first input register.
B	B Register	ALU second input register.
PSW	Program Status Word	Status flags.
MAR	Memory Address Register	RAM heap access address.
SP	Stack pointer	RAM stack access pointer.

PSW Structure

Bit	Name	Description
0

The instruction set

Every instruction is 1 to 3 bytes long. First is the opcode, and the optionnal 2 bytes are the operands. Operands can be an data (1B), address (1B), or full address (2B).

These are only real instructions. Pseudoinstruction will be defined later.

Mnemonic	Description	Pseudocode