The Machine

T32 is small enough that we can describe the whole machine on one page. That is a lovely property for learning.

Registers and pointers

T32 has four pieces of execution state you will think about most often:

• PC: the program counter, which points at the next instruction
• A: a single 8-bit general-purpose register
• DP: a 16-bit data pointer used to access memory
• SP: a 16-bit stack pointer used by stack operations and subroutines

Memory

T32 has a 64 KiB memory tape. Programs are loaded at the start of memory, and execution begins at address $0000.

This means code and data live in the same address space. In practice, many T32 programs place instructions first and data later in the file, often after a HLT or at the bottom of the source.

Flags

The virtual machine maintains two status flags:

• Z: set when the most recent result is zero
• N: set when the most recent result is negative in signed 8-bit terms

You mainly use these with conditional jumps such as JEQ and JNG.

The machine model in one sentence

Most T32 programs follow a simple rhythm:

1. point DP at some memory
2. move bytes between memory and A
3. compute in A
4. branch using flags
5. use the stack when a value must survive across calls or temporary work

That is the whole dance.

Why this design is interesting

T32 is deliberately constrained:

• only one general-purpose register
• only 32 instructions
• 8-bit arithmetic
• explicit memory movement

These constraints make data flow visible. You can often look at a short T32 program and see exactly where every value comes from and where it goes.