# 2023-09-25 — Dev notes

## TODO

- [ ] Notes on possible architecture extensions to add support for a 16-bit IP
- [ ] add tape drive to mainframe

- review 8080 style io ports
    - works bc they have 2 operands per instruction, i think

## Networking - first bits of research

- [Bus network](https://en.m.wikipedia.org/wiki/Bus_network)
- [Econet](https://en.m.wikipedia.org/wiki/Econet)
- [Telnet](https://en.wikipedia.org/wiki/Telnet)
- [Adding a serial port to my 6502 computer – Mike's Software Blog](https://mike42.me/blog/2021-07-adding-a-serial-port-to-my-6502-computer)

- uxn networking — not helpful to me, i think
    - https://github.com/klardotsh/uxnyap
    - https://compudanzas.net/uxn_tutorial_day_7.html
    - https://hacklab.nilfm.cc/xrxs/about/


## 6502 vectors

https://www.masswerk.at/6502/6502_instruction_set.html

> System Vectors
> 
> $FFFA, $FFFB ... NMI (Non-Maskable Interrupt) vector, 16-bit (LB, HB)  
> $FFFC, $FFFD ... RES (Reset) vector, 16-bit (LB, HB)  
> $FFFE, $FFFF ... IRQ (Interrupt Request) vector, 16-bit (LB, HB)  

## Docs leftovers: alternative table format for instructions

| lo ↓ / hi → | 0 (G0, M0) |
|-------------|------------|
| **0**       | END        |
| **1**       | NOP        |
| **2**       |            |
| **3**       |            |
| **4**       |            |
| **5**       |            |
| **6**       |            |
| **7**       |            |
|             |            |
| **8**       |            |
| **9**       |            |
| **A**       |            |
| **B**       |            |
| **C**       |            |
| **D**       |            |
| **E**       |            |
| **F**       |            |

| lo ↓ / hi → | 5 (G1, M1) | 6 (G1, M2) |
|-------------|------------|------------|
| **0**       | LDA #      | LDA ind    |
| **1**       | STO #      | STO ind    |
| **2**       | ADD #      | ADD ind    |
| **3**       | SUB #      | SUB ind    |
| **4**       | JMP #      | JMP ind    |
| **5**       | JEQ #      | JEQ ind    |
| **6**       | JFL #      | JFL ind    |
| **7**       | FTG #      | FTG ind    |
|             |            |            |
| **8**       | MUL #      | MUL ind    |
| **9**       | DIV #      | DIV ind    |
| **A**       | JLT #      | JLT #      |
| **B**       | JGT #      | JGT #      |
| **C**       | NOT #      | NOT #      |
| **D**       | AND #      | AND #      |
| **E**       | OR  #      | OR  #      |
| **F**       | XOR #      | XOR #      |

| lo ↓ / hi → | 9 (G2, M1) | A (G2, M2) |
|-------------|------------|------------|
| **0**       | DEV #      | DEV ind    |
| **1**       | INP #      | INP ind    |
| **2**       | OUT #      | OUT ind    |
| **3**       | FED        | FED        |
| **4**       |            |            |
| **5**       |            |            |
| **6**       |            |            |
| **7**       |            |            |
|             |            |            |
| **8**       |            |            |
| **9**       |            |            |
| **A**       |            |            |
| **B**       |            |            |
| **C**       |            |            |
| **D**       |            |            |
| **E**       |            |            |
| **F**       |            |            |

| lo ↓ / hi → | F (G3, M3) |
|-------------|------------|
| **0**       |            |
| **1**       |            |
| **2**       |            |
| **3**       |            |
| **4**       |            |
| **5**       |            |
| **6**       |            |
| **7**       |            |
|             |            |
| **8**       | RSL A      |
| **9**       | RSR A      |
| **A**       | ASL A      |
| **B**       | ASR A      |
| **C**       |            |
| **D**       |            |
| **E**       |            |
| **F**       |            |