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SPECIFICTION
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Clock Signal

github.com

Free plan macOSLinux
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Spec score 7.8 #8 of 25 in Sega Master System Emulators

What it is

Clock Signal is a free emulator for running classic software on Linux and macOS without first having to learn the original machine or emulator controls. It supports systems including the BBC Micro, Apple II, Atari 2600, Commodore Vic-20, early Macintosh, MSX, Sega Master System and ZX Spectrum. When you provide disk, tape or ROM media, it can identify and configure a machine, issue the commands needed to start the software, and speed up loading where possible. It does not import or take ownership of your files. The emulator processes video signals such as composite video and generates audio at the emulated machine’s source rate before filtering it for host output. Its README gives typical audio latency as 5–10 ms; display latency depends on host hardware. It aims for cycle-accurate emulation, which it says it achieves in some cases. Acorn Archimedes, Commodore Amiga and early PC compatible emulation is less complete than for the other listed systems. A BIOS is required. The project is MIT licensed, with macOS releases using Cocoa and Metal and Linux builds available through Qt, OpenGL or SDL options.

Spec sheet

Purpose
Clock Signal is an emulator designed to let users launch classic software directly without first learning how to use an emulator or the original machines.Read 9 Oct 2026 · github.com
License
The GitHub repository identifies the project as MIT licensed.Read 9 Oct 2026 · github.com
Accuracy
CLK attempts cycle-accurate emulation of all supported machines, and its README says this succeeds in some cases.Read 9 Oct 2026 · github.com
Emulation status
The README describes Acorn Archimedes, Commodore Amiga and early PC compatible emulation as less rounded than the other listed systems.Read 9 Oct 2026 · github.com
File handling
The README says CLK does not take ownership of users’ files and has no import procedure.Read 9 Oct 2026 · github.com
Latency
The README says audio latency is generally 5–10 ms and display latency is dictated by host hardware.Read 9 Oct 2026 · github.com
Linux and Unix builds
A Qt-based Linux build is available as a Snap, and the README says Linux, BSD and other Unix-like systems can use OpenGL with Qt or SDL builds.Read 9 Oct 2026 · github.com
macOS build
The macOS application is native Cocoa and Metal, and macOS releases are hosted on GitHub.Read 9 Oct 2026 · github.com
Recent release
The GitHub releases page lists 2026-07-23 as the latest release and describes a fix for OpenGL output affecting several emulated systems on Qt and SDL targets.Read 9 Oct 2026 · github.com
Signal processing
CLK processes video signals such as composite video and generates audio at the emulated machine’s source rate before filtering it for host output.Read 9 Oct 2026 · github.com
Single-step loading
CLK analyzes disk, tape or ROM media to select and configure a machine, issue required commands and accelerate loading where feasible.Read 9 Oct 2026 · github.com
Supported machines
It emulates numerous classic systems, including the BBC Micro, Apple II, Atari 2600, Commodore Vic-20, early Macintosh, MSX, Sega Master System and ZX Spectrum.Read 9 Oct 2026 · github.com

Plans and prices

Clock Signal Free Open-source emulator · macOS and Linux builds, plus source releases Read 9 Oct 2026 · github.com

Every Clock Signal plan and price →

Strong points and limits

Strong points

  • Identifies and configures machines from disk, tape or ROM media
  • Supports numerous classic computers and consoles
  • Does not take ownership of user files
  • Audio latency is generally 5–10 ms
  • Free and MIT licensed

Limits

  • Requires a BIOS
  • No Android support
  • Some listed machine emulation is less rounded
  • Display latency depends on host hardware

Who it suits

Clock Signal suits people who want to run classic software on Linux or macOS without managing a separate import process. Its supported systems span several well-known home computers and consoles, though emulation is less rounded for some listed systems.

Verdict

Clock Signal automates much of the setup involved in launching classic software, across a broad set of systems. Check the status of your specific machine and the BIOS requirement before choosing it.

Where Specifiction places it

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