Hi!

I will receive in two weeks some Z84C0006PEC ICs. That is what we call a Z80B, a Z80 in 40 pin package (dual-in-line, DIP format). It is pin-by-pin compatible with the good old Z80A from the MSX/MSX2/MSX2+(some models) system.

With this CPU you will be able to push your MSX up to 6,14 MHz (maximum speed supported by this CPU). You will need to change the original Z80 for this one and then change the clock signal. Further details about the different process can be seen in http://www.hansotten.com

If you are interested, please contact me by e-mail at this address:
eduardo AT robsy DOT net

Regards,

Why did you not order the Z80H?

Because Z80B had an excellent price. In addition, MSX1 computers cannot handle Z80H maximum speed clock. Z80B is bundled in Panasonic MSX2+ computers and its users would tell you wonders about it.

Perfect to make an improved upgrade from MSX2 to MSX2+.

Wonders like Z80B at 6 Mhz is 1.69 times as fast then a Z80A at 3.58 Mhz?

It is easier to switch from 3.54 to 7.16Mhz. The panasonic doesn't have a z80B, it has a chip which has an build in z80 (same chip as used in the turbo r)

You mean a S1990, msd? That's what we call, the MSX-engine, right?

no not the s1990, another chip. Don't know the number. Almost all speed up kids for the msx are 7.16Mhz, but it can be higher. 8Mhz shouldn't be a problem, but you need the right circuit to switch between them

Quote:

It is easier to switch from 3.54 to 7.16Mhz. The panasonic doesn't have a z80B, it has a chip which has an build in z80 (same chip as used in the turbo r)

Are you sure? Take a look to the description of the Panasonic models here. It says clearly that they have a Z80B.

hmm... I will look it up again. I remember that some people boosted such a 2+ computer to even a higher freq. Something of 9Mhz, this can not be done with a z80b

It's a standalone CPU, but I can't tell the model, because it is covered with a passive heatsink.

in argentina the z80B cost u$s0.33 !!!!

that price is because is too much used in old telephone things.

One time a seller offerme a lot of 10 units, at that price and i refused that. I not want to eat z80B, i preffer z80H... up to 10mhz

I am kind of looking interested at a new 8-bit computer from Russia:

http://www.eng.petersplus.ru/sprinter/

It runs Z80C at 21MHz

It is a very cool project to convert all good MSX games for this new computer. This will help it's sales to more customers.

*perfectly happy with his 7.14MHz Z80H *

But, I must say, I really can't live without it anymore (especially when using DOS2, LHEXT, and some CPU intensive demo's/games such as Illusion City and GEM). So I'd recommend the upgrade to everyone.

Btw, I don't know if you can actually use a Z80B at 6MHz. It seems more likely, or at least more simple, that you have to use them at 5,36 MHz (like the Panasonic computers do), which is a 'multiplier' of 1.5... But, there is the Turbo circuit by (I believe, correct me if I'm wrong) Alwin Henseler, which can afaik change the speed on a smooth scale, so it should also be able to do 6MHz.

Another thing, in the past, many people in the Netherlands actually used Z80B's for 7MHz circuits by overclocking them. However it didn't work with all Z80B chips, only ones from certain series. You'll have to experiment to see whether the chips from this series can be overclocked well, and ofcourse I can't say anything about the lifespan when doing that (but I think it's ok, and you can always easily replace it if you put it in a socket).

Also, Pitpan, you say "In addition, MSX1 computers cannot handle Z80H maximum speed clock." Are you referring to 7.14MHz there or to 8MHz? Because in practice even though the Z80H's can reach 8MHz they're always used at 7.14... Also, maybe it differs per machine...?


~Grauw

Quote:

It is a very cool project to convert all good MSX games for this new computer. This will help it's sales to more customers.

I'd rather have a one-chip-MSX, produced in a small professional casing .

~Grauw