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Hi, give me somebody an explanation? I simulate DS89c420 device on XTAL Freq 27MHz. After reset CPU clock is 6.75MHz and single cycle instuction's time is 148ns. I supposed 1 internal clock per 1 xtal clock. Thank you Petr
You need to read the "Ultra-High-Speed Flash Microcontroller User's Guide" http://pdfserv.maxim-ic.com/arpdf/Design/89c420_userguide.pdf Page 40 discusses instruction timing. Table 5-1 on p50 compares the instruction timings against a "standard" 8051. Section 14 gives full instruction set details, including timings.
I think I know timing of DS89c420. Default condition is one external oscillator clock per system slock and in case of internal program code memory cycle is SYSCLK/1. But when I tried to simulate this chip, timing seems to be more like High Speed Microcontroler (for example DS87c520), not like Ultra HSM. So I think this part is not fully simulated today.
You're right - UV2 currently does not simulate DS89C420 core - default Dallas high-speed core is used instead. Also, be carefull with DPTR auto increment/decrement and swap, as this also works as on DS80C320... regards Dejan