Clock Speed

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