With the clock function it is possible to specify the clock speed of the CPU for the emulated computer in MHz:
The specified default values are the actual speed of the original computer. Note that too high values will not speed up the computer as the PC processor will not be able to handle that.
When using the COMX-35, Cidelsa, TMC 600 or PECOM 64 with sound a clock frequency change will also change the sound frequency. This as the original computer derived the sound frequency from the video chip and as such the 1802 processor speed. So when increasing the speed, all sound will get higher frequencies.
In principle the emulation of the video frequency will stay the same independently of the chosen CPU frequency (except when using the CPD1861 or CDP1864). The video frequency might change if high CPU speeds are specified.
The effective CPU clock speed and vertical video frequency can be verified on the Profiler tab. Note that the values shown are real values calculated from the current emulator speed and as such might deviate from the specified clock speed value.
Default frequencies as used in Emma 02:
| Computer | CPU Frequency (MHz) | Video Type | Video Frequency (Hz) |
| CDP18S020 Evaluation Kit | 2.0 | NA | NA |
| CDP18S600: CPU 1805, UART & PIO CDP1851 | 4.9152 | NA | NA |
| CDP18S601: CPU 1802, Q/F & PIO CDP1851 CDP18S603: CPU 1802, Q/F & PIO CDP1851 CDP18S603A: CPU 1802, Q/F & PIO CDP1851 CDP18S606: CPU 1805, Q/F & PIO CDP1851 CDP18S608: CPU 1805, Q/F & PIO CDP1851 |
2.0 | NA | NA |
| CDP18S602: CPU 1802, UART & CDP1852 CDP18S605: CPU 1802 & UART CDP18S607: CPU 1805, UART & CDP1852 CDP18S610: CPU 1805 & UART |
2.4576 | NA | NA |
| CDP18S604B: CPU 1802 & CDP1852 CDP18S609: CPU 1805 & CDP1852 |
2.0971 | NA | NA |
| CDP18S661B Video (NTSC) | NA | CDP1870 | 60 |
| CDP18S661V1 Video (NTSC) | NA | CDP1870 | 60 |
| CDP18S661V3 Video (PAL) | NA | CDP1870 | 50 |
| Cidelsa | 3.579 | CDP1870 | 50 |
| COMX-35 / COMIX-35 | 2.813 2.835 |
CDP1870 CDP1870 MC6845 |
50 (PAL) 60 (NTSC) 50 |
| Cosmac Elf | 1.76 | CDP1861 MC6845 MC6847 TMS9918 |
60 |
| Cosmac Elf 2000 | 3.5795 1.7898 |
Intel 8275 CDP1861 |
60 |
| Cosmac VIP | 1.7609 | CDP1861 | 60 |
| Cosmac VIP II | 1.7898 | CDP1861 / CDP1862 | 60 |
| Cosmicos | 1.75 | CDP1864 | 50 |
| ETI-660 | 1.773 | CDP1864 | 50 |
| FRED1 | 1.0 | 32x32, 64x16 or 64x32 pixels | 60 |
| FRED1.5 | 1.0 | 32x32, 64x16 or 64x32 pixels | 60 |
| Infinite UC1800 | 1.75 | NA | NA |
| MCDS | 2.0 | NA | NA |
| Membership Card | 1.75 | NA | NA |
| Microtutor | 1.75 | NA | NA |
| Microtutor II | 1.75 | NA | NA |
| MS2000 | 2.0 | NA | NA |
| Netronics Elf II | 1.76 | CDP1861 MC6845 MC6847 TMS9918 |
60 |
| Oscom Nano | 1.75 | CDP1864 | 50 |
| Pecom 32 / 64 | 4.0 | CDP1870 | 50 |
| Pico/Elf V2 | 2.813 | NA | NA |
| Quest Super Elf | 1.76 | CDP1861 MC6845 MC6847 TMS9918 |
60 |
| RCA Studio II | 1.76 | CDP1861 | 60 |
| RCA Studio III / Victory MPT-02 | 1.76 | CDP1864 | 50 (PAL) 60 (NTSC) |
| RCA Studio IV | 3.58 | 'Studio IV' chip, probably an improved 'CDP1864' | 50 (PAL) 60 (NTSC) |
| RCA Video Coin Arcade | 1.6 | 64x32 pixels, similar to the CDP1861 | 60 |
| Telmac TMC-600 | 3.579 | CDP1870 | 50 |
| Telmac 1800 | 1.75 | CDP1861 | 60 |
| Telmac 2000 | 1.75 | CDP1864 | 50 |
| VELF | 3.579 | CDP1861 | 60 |
| VIP2K Membership Card | 4.0 | NTSC B/W 192x192 pixel graphics video output | 50 (PAL) 60 (NTSC) |
| Visicom COM-100 | 1.76 | CDP1861 | 60 |