Sol-1 is a homebrew CPU and Minicomputer built from 74HC logic. It is published here for educational purposes.
- User and Kernel privilege modes, with up to 256 processes running in parallel.
- Paged virtual memory, such that each process can have a total of 64KB RAM for itself.
- Two serial ports (16550), a real time clock(M48T02), 2 parallel ports(8255), a programmable timer(8253), an IDE hard-drive interface(2.5 Inch HDD), and a soundboard(AY-3-8910).
- 8 prioritized external interrupts
- DMA channel
- The sequencer is microcoded, with 15 ROMS operating horizontally
- 8/16-Bit MUL and DIV instructions
- Fast indexed string instructions in the spirit of x86's REP MOVSB, CMPSB, LODSB, STOSB, etc
| 16bit | 8bit | Description |
|---|---|---|
| A | AH/AL | Accumulator |
| B | BH/BL | Base Register (Secondary Counter Register) |
| C | CH/CL | Counter Register (Primary Counter) |
| D | DH/DL | Data Register / Data Pointer |
| G | GH/GL | General Register (For scratch) |
| 16bit | 8bit | Description |
|---|---|---|
| PC | Program Counter | |
| SP | Stack Pointer | |
| SSP | Supervisor Stack Pointer | |
| BP | Base Pointer (Used to manage stack frames) | |
| SI | Source Index (Source address for string operations) | |
| DI | Destination Index (Destination address for string operations) | |
| PTB | Page Table Base | |
| Status | CPU Status | |
| Flags | Arithmetic and Logic flags register | |
| TDR | TDRH/TDRL | Temporary Data Register (Internal CPU scratch register) |
- Unix-like operating system (in progress and very early)
- C compiler that generates a Sol-1 assembly output file (The output assembly is then assembled separately.)
- SystemVerilog model
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Paulo Constantino