-- THIS FILE IS A STUB ---

01/05/2024 I'm on vacancy for refresh some ideas

Jelly revision 2.0

Jelly is a concept, a alternative computer with a diferent paradigm, not for performance but for design.

Jelly is a minimal DIY 8-bit CPU made with CMOS chips, to perform computations using sequential access tapes.

What is it ?

How make a new cpu without memory address, using only sequential access, for code, data and input/output ?

I want to learn about how old cpus are made by inside and understand about signals, gates, latches, pipelines, etc.

Jelly runs a minimal language, brainfunk, based in brainfuck, a minimal Turing-complete programming language with just eight commands.

But Jelly includes few new commands to self.

Jelly uses sequential access to two ideal infinite tapes, first for code (aka ONE) and second for data (aka TWO).

Any device could emulate a tape.

PS:

The image is from https://en.freejpg.com.ar/free/info/100024149/jelly-fish-blue-water-background-sea-ocean-animal

I know that it will be slow.

Some notes are keeped at logbook .

There are a hackday log hackio .

Ideas

Jelly is not a common cpu.

• There is no general registers, just 3-state latches to keep the data bus safe.

• There is no arithmetic logical unit (ALU), just a memory with a table of unary "math" results for increment, decrement and copy a byte, and also used to decode opcodes. Could include clear, shift right, shift left, negation.

• There is no comparator, just a flag for when a byte is zero or not.

• Uses Havard architeture, with code and data in diferent tapes.

• There is no memory address, just tapes that moves forward or backward.

• The standart input and output are instant stream devices, not tapes.

And Jelly executes a esoteric language.

Brainfunk

Jelly is really, a finite state machine, running by lookup tables and executing a extended version of language brainfuck, called brainfunk, which could have more 8 commands.

Jelly does a classical Read-Eval-Print Loop, or REPL, over bytes received from a code tape. For each byte, use a lookup table to translate into a opcode and execute actions.

Not all bytes are opcodes and mapped as NOP, do nothing instruction, to catch those and just advance the code tape.

Table of OP-CODES

opcode	ascii	action	code set	name
1	>	forward a tape one step	brainfuck	forward
2	<	backward a tape one step	brainfuck	backward
3	+	increase byte at tape	brainfuck	increase
4	-	decrease byte at tape	brainfuck	decrease
5	.	output byte from tape	brainfuck	putchar
6	,	input byte into tape	brainfuck	getchar
7	[	while loop	brainfuck	while
8	]	until loop	brainfuck	until
9	!	mark end of code	jelly	halt
0	=	do nothing	jelly	noop

• Any other ascii value is just translated as (0x0) noop.
• Opcodes 10, 11, 12, 13, 14, 15 reserved and could change.

Jelly extensions

Jelly includes: (list can grow)

• a noop, to do nothing, and moves code tape one step, forward or backward;

• a eof, to end of code and halt, to be a complete Turing Machine;

Jelly ideas

How the standart devices could be changed ?

Maybe using the bytes at first two positions of data tape, to select which port to use, as input and output, as like in many microcontrolers ?

The math could include opcodes, for clear, shifts, negation, and reverse a byte.

About loops

There are some brainfuck computers, but almost with the loop instructions while and until ([ and ]) replaced by pre-compiled jumps.

Jelly does not allow pre-compiler tricks, then need a logic to deal with loops.

The while and until loops are like the concepts of any programming language, but used together.

The while ends the loop when the actual data byte is zero, then advances to pass the corresponding until.

The until repeats the loop while the actual data byte is not zero, then must go back after the corresponding while.

The loops can be nested, using a counter that increase for begins and decrease for again, finishing the loop when counter is zero. As a 8-bit circuit, the maximum nested loops is 255;

Circuit Layout

How the Jelly circuit connects is explained in circuit design

Logic Loops

How loops are implemented in Jelly is explained in logic loops

Main frame

Jelly will be a wirewrap circuit -- work in progress

Work Bench

Jelly logic circuits needs some tests -- work in progress