View source for GeckOS

{{Short description|Unix type Operating System for 6502 processor}}
{{Use dmy dates|date=May 2021}}
{{Infobox OS
| name = GeckOS
| developer = André Fachat
| family = [[Unix-like]]
| source_model = [[Open-source software|Open source]]
| kernel_type = [[Microkernel]]
| logo size = 
| screenshot = [[Image:GeckOS 20.png]]
| caption = GeckOS Shell
| latest_release_version = 2.1.1
| latest_release_date = {{Start date and age|2024|01|25}}
| latest_preview_version = 2.0.9
| latest_preview_date = {{Start date and age|2013|10|06}}
| repo = {{URL|https://github.com/fachat/GeckOS-V2}}
| supported platforms = [[MOS Technology 6502]]
| license = [[GNU General Public License|GPLv2]]
| website = [http://www.6502.org/users/andre/osa/index.html <!--"GeckOS/A65 V2.0" at -->6502.org]
| working_state = Historic
| outside = 
}}
{{Portal|Free and open-source software}}
'''GeckOS''' is a multitasking [[operating system]] for [[MOS Technology 6502|MOS 6502]], and compatible processors such as the [[MOS Technology 6510|MOS 6510]].{{Sfnp|Holmer|2019c|pp=1, 8}}  The GeckOS operating system is one of the few successful attempts to implement a Unix-like operating system on the 6502 architecture.

==Overview==
The system offers some [[Unix-like]] functionality including [[pre-emptive multitasking]], [[Multithreading (software)|multithreading]], [[semaphore (programming)|semaphores]], signals, binary [[relocation (computer science)|relocation]], [[TCP/IP]] networking via SLIP, and a 6502 [[standard library]].{{Sfnp|Holmer|2019c|p=8}}{{Sfnp|Weßling|2019|loc=3.9 Betriebssyteme}}{{Sfnp|Fachat|2013}}

GeckOS includes native support for the [[Commodore PET]] (32&nbsp;KB and 96&nbsp;KB models), [[Commodore 64]] and the CS/A65 homebrew system.{{Sfnp|Fachat|2013|loc=Download, Architecture}}  Due to the platform independent nature of the kernel code, GeckOS is advertised as an extremely easy OS to port to alternative 6502 platforms.{{cn|reason=This may, or may not, be true, but a precise citation is necessary|date=May 2021}}

Binary compatibility with the LUnix operating system can be attained when the lib6502 [[shared library]] is used.{{cn|reason=This may, or may not, be true, but a precise citation is necessary|date=May 2021}}

Due to the small fixed-location [[stack (abstract data type)|stack]] of the 6502, and because an external [[memory management unit|MMU]] is rarely provided, multitasking is somewhat limited.{{Sfnp|Holmer|2019a|loc=1m}}  The OS supports a maximum of four tasks when a shared stack space is used.{{cn|reason=This may, or may not, be true, but a precise citation is necessary|date=May 2021}}  This can be increased to sixteen tasks when stack [[snapshot (computer storage)|snapshotting]] is enabled, although this is done at the expense of some system speed.{{cn|reason=This may, or may not, be true, but a precise citation is necessary|date=May 2021}}

A [[webserver]] is integrated into the [[Serial Line Internet Protocol|SLIP]] daemon.{{Sfnp|Weßling|2019|loc=3.9 Betriebssyteme}}

==Unix on 6502 architecture==
While early versions of Unix ran on for example early model [[PDP-11]] computers that were comparable to Commodore 64 in terms of memory and processor performance there were architecture differences in terms of lack of a [[kernel mode]], only 3 [[8-bit computing|8-bit]] [[processor register|registers]] versus eight [[16-bit computing|16-bit]] general registers, and a fixed stack. These architectural limitations make implementing a Unix-like operating system on the 6502 challenging.{{Sfnp|Holmer|2019b|loc=2-5m}}

The possible non-exhaustive list of other viable Unix-like implementations on 6502 are LUnix, Asterix (Chris Baird) and ACE (Chris "Polar" Baird). GeckOS arguably is more complete in some respects, with ACE being stronger in terms of standard Unix utilities but weaker in the operating system area.{{Sfnp|Holmer|2019a|loc=3m}}

==References==
===Footnotes===
{{reflist}}

===Sources===
* {{cite book|last=Weßling|first=Holger|date=2019|title=Das Bastler-Handbuch für den THEC64 Mini
      |lang=de|publisher=Andrews UK Limited|oclc=1099619858}}
* {{cite web|last=Fachat|first=André|date=13 October 2013|title=GeckOS/A65 V2.0
      |url=http://www.6502.org/users/andre/osa/index.html|access-date=15 May 2021|website=6502.org}}
* {{Cite AV media|last=Holmer|first=Glenn|date=30 September 2019a|title=GeckOS: a Unix-like 6502 operating system
      |publisher=Vintage computer Festival Midwest
      |url=https://www.youtube.com/watch?v=jtlAOdJmeDI |archive-url=https://ghostarchive.org/varchive/youtube/20211221/jtlAOdJmeDI |archive-date=2021-12-21 |url-status=live|access-date=15 May 2021|via=[[YouTube]]}}{{cbignore}}
* {{Cite speech|last=Holmer|first=Glenn|date=7 December 2019b|title=Hacking GeckOS
      |event=[[World of Commodore]]|location=[[Toronto]], Canada
      |url=https://www.lyonlabs.org/commodore/GeckOS/HackingGeckOS.mp4|access-date=15 May 2021}}
* {{Cite web|last=Holmer|first=Glenn|date=7 December 2019c|title=Hacking GeckOS
      |url=https://www.lyonlabs.org/commodore/GeckOS/GeckOS-WoC.pdf|access-date=15 May 2021}}

== External links ==
* [https://www.lyonlabs.org/commodore/GeckOS/geckos-analysis.html Analysis, building instructions]

{{Hobbyist operating systems}}
{{Unix}}

{{DEFAULTSORT:Geckos}}
[[Category:Unix variants]]
[[Category:Commodore 64 software]]
[[Category:Free software operating systems]]
[[Category:Hobbyist operating systems]]
[[Category:Lightweight Unix-like systems]]
[[Category:Discontinued operating systems]]