Does anyone here know how much is the clock speed?
It is supposed to have versatility for a lot of applications and games ...

Any good idea about the VDP clock of MSX computers?
I want specific frequencies ...

It's twenty-some megahertz, iirc 6x the Z80's speed...

Well, at least I got a reply ...

Afaik the Z80 is clocked at 3.579MHz, making the VDP run at ~21.47 Mhz..

Are you talking about the MSX2 VDP?

Now, I got TWO replies ...

Wasn't the MSX 2 VDP like 21 Mhz and the MSX 2+ and Turbo R VDP(MSX2+) supposed to be something like 28 Mhz? This was the information that I got ...

As far as I know the V9938 and V9958 run on the same clock speed for all MSX models. It's always 6x the NTSC subcarrier frequency (same as the Z80 clock for most MSX models), so roughly 21.5MHz. The '28MHz' you heard of is probably the supposed R800 frequency.

When the turboR was released, there was little technical information available. People noticed the R800 was a *lot* faster than the Z80, and crude timing tests would show it to be anywhere from 5-10x as fast as the Z80. Since the turboR mainboard had a 28MHz chystal on it, fairly close to the R800, people assumed the R800 must therefor have a clockspeed of 28MHz.

I would guess that the 28MHz figure you heard of refers to that. I have never done any tests to see if the V9958 runs at a higher clockspeed, but I do know commands execute at the same speed as they do on MSX2 models. (In fact, they seem to execute ***slightly*** slower) If commands execute at the same speed, I guess it would be safe to assume that the clockspeed is also the same.

Quote:

When the turboR was released, there was little technical information available. People noticed the R800 was a *lot* faster than the Z80, and crude timing tests would show it to be anywhere from 5-10x as fast as the Z80. Since the turboR mainboard had a 28MHz chystal on it, fairly close to the R800, people assumed the R800 must therefor have a clockspeed of 28MHz.

What is that Crystal?
There was pictures of it ...

Check this document on expanding an ST to 1MB. You can clearly see the chrystal just above the R800.

Weird ...

OK, how do we know that the R800 runs on 7.16Mhz, internally?

According to the service manual, the chip has several clock pins:

XTAL1 is a clock (no freq given), and an OUTPUT pin
XTAL0 seems to have 28MHz, and is an INPUT pin
VCLK seems to have 14.3 MHz, and is an OUTPUT pin
SYSCLK has 7.16MHz and is an OUTPUT pin.

Which is used for what and what is the internal clock frequency?

And how is the fact that changing XTAL0 to 40MHz increases R800 speed? I guess the XTAL0 is used to drive the R800 CPU, but it's 28MHz. How do we know that it runs on 7.16 MHz then?

Also note that the turboR's service manual says that the R800 is a 16bit CPU

XTAL0 is internally devided by 4. I have one 32Mhz xtal and one 40Mhz xtal connected with a switch because the 28Mhz one broke. Both increased the speed. With 32Mhz it's devided down to 8Mhz, 40MHz is devided down to 10MHz, which also the benchmark numbers show. 40MHz gives some graphics issues on my tbr in Z80 mode.

manuel: "A CPU can be classified on the basis of the data it can access in a single operation", according to wikipedia. The ALU in R800 is 16bits, making it an 16 bit CPU. If "a single operation" is meant to be "a single assembly instruction" then even the Z80 is a 16 bit CPU