Update README.md

2022-02-12 01:33:36 +01:00
parent a36cba22ac
commit 2cd09790c6
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 # TyVM - [T]in[y] [V]irtual [M]achine
-TyVM is a 16bit VM based on the LC-3 architechture
+TyVM is a 16bit VM based on the LC-3 architechture that runs Assembly code, and could more generally run even an operating system

-### HARDWARE:
-  - 16-bit on LC-3 architecture
-  - 128kb memory
+## Resources
+https://en.wikipedia.org/wiki/Little_Computer_3
+
+### Build
+On file "preprocessor.c" define the OS where you want to run TYVM:
+
+  #define __UNIX
+
+Uncomment this line if you want to build for Unix based OS, otherwise comment it out to build for Windows
+Build using the command:
+``` 
+gcc tyvm.c -o tyvm
+```
+Or simply using makefile (optional: in makefile change binary file name wether building on Unix or Windows):
+
+``` 
+make
+```
+
+### Hardware
+TYVM is a very barebone 16-bit system on LC-3 architechture. It has:
+  - 128kb memory (65,536 memory locations)
  - 10 registers:
-    - 8 general purpose
-    - 1 program counter
-    - 1 condition register
  - 3 condition flags
+
+#### Memory
+It has 2^16(=65,536) individual memory locations
+```
+uint16_t memory[UINT16_MAX];
+```
+#### Registers
+TYVM has n.10 16-bit registers.
+    - 8 general purpose registers
+    - 1 program counter (PC)
+    - 1 conditional register (COND)
+
+```c
+enum {
+    RG_000 = 0,
+    RG_001,
+    RG_010,
+    RG_011,
+    RG_100,
+    RG_101,
+    RG_110,
+    RG_111,
+    RG_PC,
+    RG_COND,
+    RG_COUNT
+};
+uint16_t registers[R_COUNT];
+```
+#### Instruction set
+TYVM has n.16 16-bit opcodes, that instructs the machine to do some simple calculation:
+```c
+enum {           // [name, 8-bit value]
+    OP_BR = 0,      // branch, 0000
+    OP_ADD,         // add, 0001
+    OP_LD,          // load, 0010
+    OP_ST,          // store, 0011
+    OP_JSR,         // jump register, 0100
+    OP_AND,         // bitwise and, 0101
+    OP_LDR,         // load register, 0110
+    OP_STR,         // store register, 0111
+    OP_RTI,         // unused opcode
+    OP_NOT,         // bitwise not, 1001
+    OP_LDI,         // indirect load, 1010
+    OP_STI,         // indirect store, 1011
+    OP_JMP,         // jump, 1100
+    OP_RES,         // reserved opcode,
+    OP_LEA,         // load effective address, 1110
+    OP_TRAP,        // execute trap, 1111
+};
+```
+
+### Logic
+10  Load instruction from memory at program counter [RG_PC] address;
+20  Increment RG_PC;
+30  Read opcode for next instruction;
+40  Perform instruction read in 40;
+50  Goto 10;
+
+### Usage
+```bash
+./tyvm <*.asm>
+```
+
+- Below is a `hello-word` program for `TYVM`, the assembled program can be found in `asm` directory
+```shell
+.ORIG x3000
+LEA R0, HENLO_WORLD
+PUTS
+HALT
+HELLO_STR .STRINGZ "Henlo World!"
+.END
+```