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