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Difference between revisions of "/aig/ Alternative ISA General"

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(Added category and virtual processors such as DCPU-16 and the p-machine plus Symb-OS for Z-80)
(Beginning restructuring with more on ISA and example architectures, starting with 8-bit.)
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While discussion of Intel or AMD hardware is not absolutely prohibited (and even if it were, who is gonna enforce this? LOL), due to the ubiquity of x86 hardware, it is assumed that whatever concerns such architecture can be discussed in any of the other gorillion threads on the board.
 
While discussion of Intel or AMD hardware is not absolutely prohibited (and even if it were, who is gonna enforce this? LOL), due to the ubiquity of x86 hardware, it is assumed that whatever concerns such architecture can be discussed in any of the other gorillion threads on the board.
 +
 +
Old threads are available on [https://desuarchive.org/g/search/subject/aig/type/op/ Desuarchive].
  
 
== Ongoing projects ==
 
== Ongoing projects ==
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== Resources ==
 
== Resources ==
 
Anon has been kind enough to put together a small [https://mega.nz/file/0PplHSyL#eK_f2ZSc2f0E8_RLUGz9nVn40myXhyiRDMU_FhgO2wk reference library].
 
Anon has been kind enough to put together a small [https://mega.nz/file/0PplHSyL#eK_f2ZSc2f0E8_RLUGz9nVn40myXhyiRDMU_FhgO2wk reference library].
 +
 +
A collection of brief infocards for many different processors is available on [http://www.textfiles.com/programming/CARDS/ TextFiles] which also holds huge archives relating to programming and microcomputers, especially 8-bit processors.
 +
 +
 +
= ISA Overview =
 +
ISA simply means Instruction Set Architecture. This is what the programmer sees from the outside, which these days is very different from the microcode and state machines operating inside the processors, normally inaccessible for normal programmers. The mid 1970's saw a Cambrian explosion of architectures that later fossilised into what we see today. Any assembly programmer and academics such as Hennessy and Patterson agree that x86 stinks, but as usual inertia and money trumps speed, efficiency and elegance. Those three qualities are what we instead celebrate in this general.
 +
 +
The same ISA can be implemented by many different internal architectures and microcode. The ISA is the main topic but since many architectures are DIY we discuss both. The best way is to illustrate by examples of processors. An ISA is defined by a fairly large set of parameters
 +
 +
Registers: few or many. Few is good for low latency, many registers are good for lazy programmers and poor compilers. One cannot avoid noting modern processors have tons of registers but still seem sluggish.
 +
 +
Register use: accumulator based where all processing is via one (or 2, rarely more) main register; stack based where everything is performed on a stack; or register file where many registers can be used in similar ways.
 +
 +
Operands: 2-op instructions of the form A += X; or 3-op instructions of the form A = B + C. The former requires a little extra thought but 3-op is simple for lazy programmers and poor compilers. One cannot avoid noting modern processors drift towards 3-op instructions
 +
 +
Modes: Implied, immediate, absolute, absolute indexed, zeropage, zeropage indexed, stack relative, index indirect, indirect indexed, all with our without pre/post increment/decrement.
 +
 +
Much can be summarised as CISC that is complex, or RISC which is simple. The RISC definition has drifted over the decades, and changed from "simple" to register-to-register based operations with load-store memory handling.
 +
 +
 +
== Processors ==
 +
 +
=== 8 Bit Processors ===
 +
These usually have 8 bit registers and a 16 bit program counter or instruction pointer (terminologies vary) and could access 64 KB memory. Most were accumulator based which worked well since in this era memory and CPUs were equally slow.
 +
 +
==== 1802 ====
 +
This is a weird and wonderful processor implemented as bit serial architecture, which made it slow. It was still popular for games on machines such as Cosmac ELF. The fabrication made it radiation resistant and it was also popular for satellites, and is still in production.
 +
 +
==== 6502 ====
 +
The 6502 had one accumulator (A), two index registers (X and Y), a stack pointer (S) and a processor status (P), all 8 bit wide; plus a 16 bit program counter (PC). It also had a zero page that could be used as address registers. It entered the market at a much lower price than 6800 and quickly won a following. It was used in many popular computers of that era including Apple 2, BBC and Commodore 64. For all the limitations it was powerful enough in the hands of skilled programmers to power the first spreadsheet (VisiCalc) which was also the first killer application, as well as 3D space games with hidden line wireframe graphics such as Elite.
 +
 +
The 6502 still has many loyal fans, a [http://6502.org/ hugely active community] and dozens of implementations. It is still supported commercially by [https://www.westerndesigncenter.com/ The Western Design Center], founded by the original designer. An estimated 200 million chips are made annually for an installed base estimated at 2 billion. Not bad for a nearly 50 year old design. This time span also means it is proven, and is therefore used in applications such as pacemakers, where lifetime guarantees take on an entirely new meaning.
 +
 +
The 6502 has two weaknesses. First of all it is awkward for 16 bit pointer handling, which is why The Woz overcame this by making SWEET-16 virtual processor. The second is that the 6502 is not suited for stack intensive languages such as C. This has been overcome by other virtual processors such as the p-machine.
 +
 +
 +
==== 6800 ====
 +
 +
==== 6809 ====
 +
This was the peak of 8-bit architectures, and even featured an opcode for multiplication. Hitachi got a license and made the 6309 variant that includes more registers
 +
 +
==== Z-80 ====
 +
 +
  
 
== Links ==
 
== Links ==
  
 +
The following is mostly a list of bookmarks.
  
 
'''Amiga (Motorola 68k)'''
 
'''Amiga (Motorola 68k)'''

Revision as of 13:13, 20 August 2021

Alternative ISA General is a discussion thread about non x86 hardware. "Alternative" doesn't mean "unpopular" it means "alternative to x86". While there have been such threads in the past, they were usually sporadic and not very well connected with one another, which meant that whatever transpired in one thread wasn't carried over to the next one.

Due to the rise of desktop-class ARM chips, interest in alternative hardware has risen, with many Anons even coming up with projects of their own. Therefore, a centralised place was needed, where we could keep track of the development and goals of the community.

While discussion of Intel or AMD hardware is not absolutely prohibited (and even if it were, who is gonna enforce this? LOL), due to the ubiquity of x86 hardware, it is assumed that whatever concerns such architecture can be discussed in any of the other gorillion threads on the board.

Old threads are available on Desuarchive.

Ongoing projects

Anons are currently interested in porting several open source projects to the PowerPC architecture. Currently the following proposals have been made:

Grand Theft Auto III

Re3 is a homebrew engine intended to replace proprietay RenderWare with an open source implementation. Anons have been discussing making a port for the 32-bit PowerPC version of Mac OS X.

The Elder Scrolls III: Morrowind

OpenMW is a free and open source modern re-implementation of the Gamebryo engine.

Tomb Raider

OpenLara is a Classic Tomb Raider open-source engine.

Resources

Anon has been kind enough to put together a small reference library.

A collection of brief infocards for many different processors is available on TextFiles which also holds huge archives relating to programming and microcomputers, especially 8-bit processors.


ISA Overview

ISA simply means Instruction Set Architecture. This is what the programmer sees from the outside, which these days is very different from the microcode and state machines operating inside the processors, normally inaccessible for normal programmers. The mid 1970's saw a Cambrian explosion of architectures that later fossilised into what we see today. Any assembly programmer and academics such as Hennessy and Patterson agree that x86 stinks, but as usual inertia and money trumps speed, efficiency and elegance. Those three qualities are what we instead celebrate in this general.

The same ISA can be implemented by many different internal architectures and microcode. The ISA is the main topic but since many architectures are DIY we discuss both. The best way is to illustrate by examples of processors. An ISA is defined by a fairly large set of parameters

Registers: few or many. Few is good for low latency, many registers are good for lazy programmers and poor compilers. One cannot avoid noting modern processors have tons of registers but still seem sluggish.

Register use: accumulator based where all processing is via one (or 2, rarely more) main register; stack based where everything is performed on a stack; or register file where many registers can be used in similar ways.

Operands: 2-op instructions of the form A += X; or 3-op instructions of the form A = B + C. The former requires a little extra thought but 3-op is simple for lazy programmers and poor compilers. One cannot avoid noting modern processors drift towards 3-op instructions

Modes: Implied, immediate, absolute, absolute indexed, zeropage, zeropage indexed, stack relative, index indirect, indirect indexed, all with our without pre/post increment/decrement.

Much can be summarised as CISC that is complex, or RISC which is simple. The RISC definition has drifted over the decades, and changed from "simple" to register-to-register based operations with load-store memory handling.


Processors

8 Bit Processors

These usually have 8 bit registers and a 16 bit program counter or instruction pointer (terminologies vary) and could access 64 KB memory. Most were accumulator based which worked well since in this era memory and CPUs were equally slow.

1802

This is a weird and wonderful processor implemented as bit serial architecture, which made it slow. It was still popular for games on machines such as Cosmac ELF. The fabrication made it radiation resistant and it was also popular for satellites, and is still in production.

6502

The 6502 had one accumulator (A), two index registers (X and Y), a stack pointer (S) and a processor status (P), all 8 bit wide; plus a 16 bit program counter (PC). It also had a zero page that could be used as address registers. It entered the market at a much lower price than 6800 and quickly won a following. It was used in many popular computers of that era including Apple 2, BBC and Commodore 64. For all the limitations it was powerful enough in the hands of skilled programmers to power the first spreadsheet (VisiCalc) which was also the first killer application, as well as 3D space games with hidden line wireframe graphics such as Elite.

The 6502 still has many loyal fans, a hugely active community and dozens of implementations. It is still supported commercially by The Western Design Center, founded by the original designer. An estimated 200 million chips are made annually for an installed base estimated at 2 billion. Not bad for a nearly 50 year old design. This time span also means it is proven, and is therefore used in applications such as pacemakers, where lifetime guarantees take on an entirely new meaning.

The 6502 has two weaknesses. First of all it is awkward for 16 bit pointer handling, which is why The Woz overcame this by making SWEET-16 virtual processor. The second is that the 6502 is not suited for stack intensive languages such as C. This has been overcome by other virtual processors such as the p-machine.


6800

6809

This was the peak of 8-bit architectures, and even featured an opcode for multiplication. Hitachi got a license and made the 6309 variant that includes more registers

Z-80

Links

The following is mostly a list of bookmarks.

Amiga (Motorola 68k)

amigaXfer, an easy-to-use GUI tool for lightning fast disk/file transfers on the serial port with the Amiga

Amiga 3000 running PPC software on KillerNIC NPU.

Amiga Hardware Database

Amiga Wiki

Compiled list of free/open sources related to classic Commodore Amiga computers

FS-UAE (Amiga emulator) released for Apple Silicon arm architecture

Amiberry (Emulate an Amiga on on your Raspberry Pi)

Amiberry how-to


Atari (Motorola 68k)

Atari Museum

FireBee Atari-compatible computer

FreeMiNT Project Website

ARAnyM (Atari Running on Any Machine) VM Software


Other Motorola 68k Links

Motorola 68000 computer

News around Motorola 680x0 CPU computer systems

Motorola 680x0 Resources


MIPS

Emulate Windows NT 4.0 MIPS version (translated)

A guide to running IRIX 6.5.22 in MAME

IRIX Introduction

MIPS is back (translated)

Windows NT 3.50/MIPS installation on QEMU/MIPS


NMOS 6502

C64 Resources

Commodore 64 Preservation Project

Commodore 64 Resources

Commodore Computer Club - USA

Developing for the 6502 microprocessor and its relatives

The 6502 microprocessor Resource

Interactive in-browser course

"SWEET 16" Explainer

6502 ISA Code Chart


POWER/PowerPC

About Power9

Compiling for Powerpc, how to?

Evolution of PowerPC

Fixing Radeon Linux graphics on PowerPC

GNU/Linux Open Hardware PowerPC notebook

More about Spectre and the PowerPC (or why you may want to dust that G3 off)

http://bgafc.t-hosting.hu/oses4ppc.php Operating Systems for PowerPC

Power Macintosh


RISC-V

Haiku RISC-V port progress

SiFive: The Direction and Magnitude of SiFive Intelligence


SPARC

The Resurgence of SPARC/Solaris (Okamoto Rikiya)

SPARC Internacional, Inc.


SuperH

Hitachi SuperH RISC Engine (Kawasaki Ikuya et al)

SuperH RISC engine Family Features


VAX

The Computer History Simulation Project

VAX MP: SIMH VAX simulator able to execute OpenVMS (VAX/VMS)

VAX in FPGA

VAX extended to 64 bits


Z80

Sharp PC-1500 (TRS-80 PC-2) resource page

ZX Spectrum Next

Symb-OS is a multitasking windowing OS for Z-80


Hardware Reimplementation

An interesting fpga handheld is being crowdfunded, with a focus on security

FPGA-related repositories on GitHub

Homebrew Cray-1A

MiSTer wiki


Raspberry Pi (arm)

Raspberry Pi hardware


Apple Silicon (arm)

Apple M1 SoC Tech Specs

Check if an app is native Apple Silicon or not yet

Apple MacBook Air (2020, M1)

SSD wear "issue" is FUD

Apple fixes incorrect wear reporting


Virtual Processors

DCPU-16 was a virtual processor intended for the game 0x10c.

The p-code machine was a stack based virtual processor used by UCSD Pascal on Apple 2 and other machines.


Other

Developing for all sorts of CPU

ForwardCom Instruction Set

FrogFind search engine

High-energy Electron Beam Lithography for Nanoscale Fabrication

Transputer Instruction Set