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https://github.com/drujensen/tiny16

A custom 16 bit ISA for the TinyFPGA BX resembling risc-v and c6502.
https://github.com/drujensen/tiny16

Last synced: 10 days ago
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A custom 16 bit ISA for the TinyFPGA BX resembling risc-v and c6502.

Host: GitHub
URL: https://github.com/drujensen/tiny16
Owner: drujensen
License: apache-2.0
Created: 2023-09-04T05:19:45.000Z (over 1 year ago)
Default Branch: main
Last Pushed: 2024-02-17T05:46:28.000Z (10 months ago)
Last Synced: 2024-10-25T01:35:39.588Z (about 2 months ago)
Language: Verilog
Homepage:
Size: 285 KB
Stars: 0
Watchers: 2
Forks: 0
Open Issues: 0
Metadata Files:
- Readme: README.md
- License: LICENSE

Awesome Lists containing this project

README

        # Tiny16 Computer

The Tiny16 computer is a 16bit system built on the TinyFPGA B-Series.  The system

has similar capabilites as a C6502 8bit system.

The computer can support 128KB of RAM and has a 16bit bus and instruction set.  memory is 16bit per address location instead of 8bit. This keeps the system 16bit aligned with no special handling.  everything is 16bits.

## Instruction Set Architecture

The system has 16 base opcodes.  This is the first 4 bits of the 16bit fixed width commands.

### System Instructions

 | OPCODE (4) | FUNCT (4) | DEST (4) | SRC (4) | Description |

 |-------|-------|--------|-------|--------------|

 | 0 SYS | 0 NOP | x0:x15 | 0:x15 | No Operation |

 | 0 SYS | 1 IN  | x0:x15 | 0:x15 | input from keyboard |

 | 0 SYS | 2 OUT | x0:x15 | 0:x15 | output to display |

 | 0 SYS | 3 SET | x0:x15 | 0:x15 | set register |

 | 0 SYS | 4 CLR | x0:x15 | 0:x15 | clear register |

 | 0 SYS | 14 INT| x0:x15 | 0:x15 | interrupt handler |

 | 0 SYS | 15 HLT| x0:x15 | 0:x15 | halt cpu |

### Memory Instructions

 | OPCODE (4) | DEST (4) | VAL (8) | Description |

 |-------|---------|-------------|--------------|

 | 1 LLI |  x0:x15 | lower value | Load lower 8 bits |

 | 2 LUI |  x0:x15 | upper value | Load upper 8 bits |

 | OPCODE (4) | FUNCT (4) | DEST (4) | SRC (4) | Description |

 |-------|-------|--------|--------|--------------|

 | 3 MEM | 1 LD  | x0:x15 | x0:x15 | Load from register |

 | 3 MEM | 2 ST  | x0:x15 | x0:x15 | Store to register |

 | 3 MEM | 3 LDP | x0:x15 | x0:x15 | Load from memory |

 | 3 MEM | 4 STP | x0:x15 | x0:x15 | Store to memory |

### Arithmetic/Logic Instructions

| OPCODE (4) | FUNCT (4) | DEST (3) | SRC (4) | Description |

|------------|-----------|----------|---------|-------------|

| 4 MATH | 0 ADD | x0:x15 | x0:x15 | Add |

| 4 MATH | 1 SUB | x0:x15 | x0:x15 | Subtract |

| 4 MATH | 2 ADC | x0:x15 | x0:x15 | Add with Carry |

| 4 MATH | 3 SBC | x0:x15 | x0:x15 | Subtract with Carry |

| 5 LOGIC | 0 AND | x0:x15 | x0:x15 | And |

| 5 LOGIC | 1 OR  | x0:x15 | x0:x15 | Or |

| 5 LOGIC | 2 XOR | x0:x15 | x0:x15 | Xor |

| 5 LOGIC | 3 NOT | x0:x15 | x0:x15 | Xor |

| 6 SHIFT | 0 SLA  | x0:x15 | x0:x15 | Shift Left Arithmetic |

| 6 SHIFT | 1 SRA  | x0:x15 | x0:x15 | Shift Right Arithmetic|

| 6 SHIFT | 2 SLL  | x0:x15 | x0:x15 | Shift Left Logical |

| 6 SHIFT | 3 SRL  | x0:x15 | x0:x15 | Shift Right Logical|

| 7 MULT | 0 MLT | x0:x15 | x0:x15 | Multiply |

| 7 MULT | 1 DIV  | x0:x15 | x0:x15 | Divide |

| 7 MULT | 2 MOD | x0:x15 | x0:x15 | Modulus |

### Branch Instructions

| OPCODE (4) | FUNCT (4) | DEST (4) | SRC (4) | Description |

|--------|--------|--------|--------|--------------|

| 8 JUMP | 0 JALR | x0:x15 | x0:x15 | Jump And Link Register |

### Branch Instructions

| OPCODE (4) | FUNCT (4) | DEST (4) | SRC (4) | Description |

|--------|--------|--------|--------|--------------|

| 9 BRANCH | 0 BEQ | x0:x15 | x0:x15 | Branch if Zero Set |

| 9 BRANCH | 1 BNE | x0:x15 | x0:x15 | Branch if Zero Clear |

| 9 BRANCH | 2 BLT | x0:x15 | x0:x15 | Branch if Negative Set |

| 9 BRANCH | 3 BGE | x0:x15 | x0:x15 | Branch if Negative Clear |

| 9 BRANCH | 4 BCS | x0:x15 | x0:x15 | Branch if Carry Set |

| 9 BRANCH | 5 BCC | x0:x15 | x0:x15 | Branch if Carry Clear |

| 9 BRANCH | 6 BOS | x0:x15 | x0:x15 | Branch if Overflow Set |

| 9 BRANCH | 7 BOC | x0:x15 | x0:x15 | Branch if Overflow Clear |

### Stack Instructions

| OPCODE (4) | FUNCT (4) | DEST (4) | SRC (4) | Description |

|--------|--------|--------|--------|--------------|

| 10 STACK | 0 PUSH | x0:x15 | x0:x15 | Push Register to Stack |

| 10 STACK | 1 POP  | x0:x15 | x0:x15 | Pop Register from Stack |

## Registers:

| Register | Label | Alias | Description |

|----------|-------|-------|-------------|

| 0 | X0 | ZERO | Always Zero |

| 1 | X1 | PC | Program Counter |

| 2 | X2 | SP | Stack Pointer |

| 3 | X3 | BA | Branch Address |

| 4 | X4 | RA | Return Address (Saved) |

| 5 | X5 | S0 | Saved 0 |

| 6 | X6 | S1 | Saved 1 |

| 7 | X7 | S2 | Saved 2 |

| 8 | X8 | S3 | Saved 3 |

| 9 | X9 | S4 | Saved 4 |

| 10 | X10 | A0 | Argument 0 / Return 0 |

| 11 | X11 | A1 | Argument 1 |

| 12 | X12 | A2 | Argument 2 |

| 13 | X13 | A3 | Argument 3 |

| 14 | X14 | A4 | Argument 4 |

| 15 | X15 | A5 | Reserved |

## Alias Instructions

| Alias         | Instructions |

|---------------|--------------|

| LDI Rd 0xhhll | LUI Rd 0xhh  |

|               | LLI Rd 0xll  |

| LDI Rd :label | LUI Rd :label[15:8] |

|               | LLI Rd :label[7:0]  |

| JMP :delay    | LUI BA :label[15:8] |

|               | LLI BA :label[7:0]  |

|               | JALR X0 BA   |

| JSR :delay    | LUI BA :label[15:8] |

|               | LLI BA :label[7:0]  |

|               | JALR RA BA   |

| RET           | JALR X0 RA   |

| PSHR          | PSH S4       |

|               | PSH S3       |

|               | PSH S2       |

|               | PSH S1       |

|               | PSH S0       |

|               | PSH RA       |

| POPR          | POP RA       |

|               | POP S0       |

|               | POP S1       |

|               | POP S2       |

|               | POP S3       |

|               | POP S4       |

## Setup

Install [icestorm](http://www.clifford.at/icestorm/) for your computer once:

```sh

sudo apt-get install build-essential clang bison flex libreadline-dev \

                     gawk tcl-dev libffi-dev git mercurial graphviz   \

                     xdot pkg-config python python3 libftdi-dev

git clone https://github.com/cliffordwolf/icestorm.git icestorm

cd icestorm

make -j$(nproc)

sudo make install

cd ..

git clone https://github.com/cseed/arachne-pnr.git arachne-pnr

cd arachne-pnr

make -j$(nproc)

sudo make install

cd ..

git clone https://github.com/cliffordwolf/yosys.git yosys

cd yosys

make -j$(nproc)

sudo make install

cd ..

pip install --user tinyprog

```

## Build

Build the project:

```shell

make clean

make build

```

## Test

Run the testbench:

```shell

make test

open tiny16.vcd

```

## Install

Install on the board:

```shell

make prog

```

# Contributing

## TODO

- [ ] add .text, .data, .end sections with address

- [ ] implement uart for terminal support

- [ ] create wozman for firmware operating system

- [ ] support interrupts

- [ ] support memory mapped devices

- [ ] support flash for program storage

- [ ] create c6502 transpiler