Xerxes a écrit : ↑28 nov. 2017 14:02This is pretty fast for 640 kHz and a precision of 64 bit.
I've checked the service manual of the 71B for more details about the CPU clock speed. If I'm not mistaken, the frequency
of 640 kHz refers to the internal machine cycle, that consists of 4 clock cycles. So if we want to compare different CPUs,
it's better to use the clock cycles and not the machine cycles, because some CPUs have varying machine cycle length.
The correct frequency of the 71B should be 2.4-2.6 MHz normally, that gives a machine cycle speed of 600-650 kHz.
Some examples of the needed clock cycles for one machine cycle:
Zilog Z80 3-6
HP Saturn 4
CASIO HD61700 2-3 (PB-1000)
SHARP SC61860 3 (PC-1360)
SHARP SC62015 3 (PC-E500)
A comparison of the BCD performance using the execution time of a 16 digit addition command:
SHARP SC61860 93 cycles @ 768 kHz = 8258/s
CASIO HD61700 47 cycles @ 910 kHz = 19362/s
HP Saturn 82 cycles @ 2.5 MHz = 30488/s
SHARP SC62015 63 cycles @ 2.3 MHz = 36508/s