Varvara - Revision history

Pixelbath: formatting

2022-11-28T04:46:37Z

formatting

← Older revision		Revision as of 23:46, 27 November 2022
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	{{stub}}		{{stub}}

	'''Varvara''' is a fantasy computer system that uses runs a stack-based virtual machine called '''Uxn'''. Its main programming language is a Forth-like language called Uxntal.		'''Varvara''' is a fantasy computer system that uses runs a stack-based virtual machine called '''Uxn'''. Its main programming language is a Forth-like assembly language called '''Uxntal'''.

	== Uxn ==		== Uxn ==

Pixelbath: a little more cpu info

2022-11-28T04:27:03Z

a little more cpu info

← Older revision		Revision as of 23:27, 27 November 2022
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	=== Memory ===		=== Memory ===
	~~The Uxn virtual CPU can address~~ 64kb of memory~~; 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.		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"		{\| class="wikitable"
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	\| 256 bytes		\| 256 bytes
	\|}		\|}
	~~Uxn is~~ a single~~-page virtual machine with 32 opcodes~~. This ~~system has no registers, and instead uses~~ a ~~127-level stack~~.
			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.

	== Devices ==		== Devices ==
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	\| a b>>c8l<<c8h		\| a b>>c8l<<c8h
	\|}		\|}

			The Uxn CPU reads one byte at a time from the main memory starting at 0100. The program counter is a 16-bit word that indicates the address of the byte to read next. Each byte read corresponds to an opcode which may cause a change in the stack(s) or the normal flow of the program counter; instead of pointing to the next byte in memory, it can be made to point elsewhere, "jumping" from one place in memory to another.


	[[Category: Fantasy computers]]		[[Category: Fantasy computers]]

Pixelbath: +uxntal

2022-11-28T03:55:25Z

+uxntal

← Older revision		Revision as of 22:55, 27 November 2022
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	The two reserved devices can be used for implementation specific features that do not need to be part of the specs, or other Uxn/Varvara instances.		The two reserved devices can be used for implementation specific features that do not need to be part of the specs, or other Uxn/Varvara instances.

			== Uxntal ==

			According to the implentation spec, "Tal is the programming language for the Uxn virtual machine." Tal, commonly referred to as '''Uxntal''', is a unique flavor of assembly language. Uxntal source files are assembled from human-readable source files into Uxn-compatible ROM files with the .tal extension.

			The language itself works similarly to Forth, another stack-based language.

			=== Opcodes ===

			Uxn can perform 32 different operations, and each operation has 3 possible modes. The items in the following table include the Program Counter(PC), Memory(M), Devices(D) and Return Stack(rs).

			{\| class="wikitable"
			\|-
			!colspan="2"\|Stack
			!colspan="2"\|Memory
			\|-
			\| '''BRK/LIT''' - Literal
			\| a b c M[PC+1]
			\| '''LDZ''' - Load Zeropage
			\| a b M[c8]
			\|-
			\| '''INC''' - Increment
			\| a b c+1
			\| '''STZ''' - Save Zeropage
			\| a {M[c8]=b}
			\|-
			\| '''POP''' - Pop
			\| a b
			\| '''LDR''' - Load Rel
			\| a b M[PC+c8]
			\|-
			\| '''NIP''' - Nip
			\| a c
			\| '''STR''' - Save Rel
			\| a {M[PC+c8]=b}
			\|-
			\| '''SWP''' - Swap
			\| a c b
			\| '''LDA''' - Load Abs
			\| a b M[c16]
			\|-
			\| '''ROT''' - Rotate
			\| c b a
			\| '''STA''' - Save Abs
			\| a {M[c16]=b}
			\|-
			\| '''DUP''' - Duplicate
			\| a b c c
			\| '''DEI''' - Device In
			\| a b D[c8]
			\|-
			\| '''OVR''' - Over
			\| a b c b
			\| '''DEO''' - Device Out
			\| a {D[c8]=b}
			\|-
			!colspan="2"\|Logic
			!colspan="2"\|Arithmetic
			\|-
			\| '''EQU''' - Equal
			\| a b?c
			\| '''ADD''' - Add
			\| a b+c
			\|-
			\| '''NEQ''' - Not Equal
			\| a b!c
			\| '''SUB''' - Subtract
			\| a b-c
			\|-
			\| '''GTH''' - Greater
			\| a b>c
			\| '''MUL''' - Multiply
			\| a b*c
			\|-
			\| '''LTH''' - Lesser
			\| a b<c
			\| '''DIV''' - Divide
			\| a b/c<br />
			\|-
			\| '''JMP''' - Jump<br />
			\| a b {PC+=c}
			\| '''AND''' - And
			\| a b&c
			\|-
			\| '''JCN''' - JumpCond
			\| a {(b8)PC+=c}
			\| '''ORA''' - Or
			\| <nowiki>a b\|c</nowiki>
			\|-
			\| '''JSR''' - JumpStash
			\| a b {rs.PC PC+=c}
			\| '''EOR''' - ExclusiveOr
			\| a b^c
			\|-
			\| '''STH''' - Stash
			\| a b {rs.c}
			\| '''SFT''' - Shift
			\| a b>>c8l<<c8h
			\|}

	[[Category: Fantasy computers]]		[[Category: Fantasy computers]]

Pixelbath: fixed category again

2022-11-28T02:06:31Z

fixed category again

← Older revision		Revision as of 21:06, 27 November 2022
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	[[Category: Fantasy ~~Computers~~]]		[[Category: Fantasy computers]]

Pixelbath: fixed category

2022-11-28T02:06:08Z

fixed category

← Older revision		Revision as of 21:06, 27 November 2022
Line 63:		Line 63:


	[Category: Fantasy Computers]		[[Category: Fantasy Computers]]

Pixelbath: initial page; incomplete

2022-11-28T02:05:37Z

initial page; incomplete

New page

{{stub}}

'''Varvara''' is a fantasy computer system that uses runs a stack-based virtual machine called '''Uxn'''. Its main programming language is a Forth-like language called Uxntal.

== Uxn ==

=== Memory ===
The Uxn virtual CPU can address 64kb of memory; 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
|}
Uxn is a single-page virtual machine with 32 opcodes. This system has no registers, and instead uses a 127-level stack.

== Devices ==

Devices are external systems connected to the Uxn CPU, such as the screen, the mouse and the keyboard. Each device has 16 bytes, also called ports, of I/O memory. Vectors are ports holding an address in memory to evaluate when a device event is triggered, such as when the mouse is moved, or a key is pressed.

* 00 - System device
* 10 - Console device
* 20 - Screen device
* 30, 40, 50, 60 - Audio device
* 70 - MIDI device
* 80 - Controller
* 90 - Mouse
* a0, b0 - File
* c0 - Datetime
* d0 - Unused
* e0, f0 - Reserved

The two reserved devices can be used for implementation specific features that do not need to be part of the specs, or other Uxn/Varvara instances.

[Category: Fantasy Computers]