Editing Varvara (section)

=== Memory ===
Memory in a uxn computer consists in four separate areas: Main RAM with 64kb, 256 bytes each of: I/O memory, working stack, and return stack. Programs can move stacks into addressable range to allow reading and writing directly into stack memory. In this way, peripherals such as a controller, mouse, and keyboard can be addressed.

{| class="wikitable" 
|- style="vertical-align:top;"
! Memory
| RAM
| Data
| 64kb
|- style="vertical-align:top;"
!rowspan="6"|Stacks
|rowspan="3"|Working Stack
| Data
| 254 bytes
|-
| Error
| 1 byte
|-
| Pointer
| 1 byte
|- style="vertical-align:top;"
|rowspan="3"|Return Stack
| Data
| 254 bytes
|-
| Error
| 1 byte
|-
| Pointer
| 1 byte
|-
! I/O
| Devices
| Data
| 256 bytes
|}

Each byte in main memory has an address of 16 bits (2 bytes) in size, while each byte in the i/o memory has an address of 8 bits (1 byte) in size. Both can be accessed randomly.

The first 256 bytes of the main memory constitute a section called the "zero page". this section can be addressed by a single byte and it is meant for data storage during runtime. The main memory stores the program to be executed starting at the 257th byte, or 0x100. This byte is the 0100 starting memory address for a Uxntal program.