Z80 at 99MHz

by snout on 09-01-2004, 12:46
Topic: Hardware
Languages:

The Z80, the core of the MSX Computer, is used for many, many other purposes and therefor the best-selling CPU ever. According to Zilog, this processor was used in over a billion end-use devices world wide. One of those devices is the Nintendo Gameboy. On this website, a Gameboy was heavily modified, adding a harddisk. After freezing both the harddisk and processor at -10 Celcius, they succeeded running the Z80 at 99MHz. Not bad for a processor from the 70's! The gameboy was still capable of running Tetris, but after pushing start things would go so fast, that the Game-over screen instantly appeared. As far as we know, this kind of overclocking has never been attempted on MSX, probably because the VDP would slow the system down anyway. There are however many MSX2 computers that run on 7 or 8 MHz, and there are some people who have upgraded their turboR to 40MHz. The latter already needs some modifications to keep the VDP working.

Relevant link: Z80 at 99MHz

Comments (16)

By BiFi

Enlighted (4348)

BiFi's picture

09-01-2004, 12:50

Talk about extreme overkill. Cooling it in the freezer part of the refridgerator. And still it works.

By jalu

Master (158)

jalu's picture

09-01-2004, 14:22

Ok, I'll consider building my tR in a fridge now, maybe then I can play MP3's with it... Smile

By mfeingol

Champion (291)

mfeingol's picture

09-01-2004, 17:29

I believe that the article is a joke. I doubt it's possible to run a 3.5 MHz CPU at 99 MHz, regardless of cooling.

By flyguille

Prophet (3028)

flyguille's picture

09-01-2004, 18:04

WOOOOOOWWW!!! I already have the cocaine and where are the girls?????

That HD without his case run after freeze??? and the humidity?

If a micro TMS can run 4 times the nominal speed without a cooling system, perhaps it can the z80 to run at 99mhz!!, but I don't believe myself that it took 4 hours in heating...... I give him 30 seconds.

That pity the impossibility of taking it to practices it daily

By flyguille

Prophet (3028)

flyguille's picture

09-01-2004, 18:11

the limitation for a chip to run faster are the following.

1 The electric loses making heat.

2 the loss of data for the residual capacities of the floodgates that compose the chip

1 ---> is the big problem.

2 ---> is a minor problem for higher freq. To more residual capacities more loses data in turbo speeds and that is more heat.

The chip afte that ¿continuos work?, because the z80 case can be cold, but the chip inside, are at higher temp everytime.

By Arjan

Paladin (742)

Arjan's picture

09-01-2004, 18:19

indeed, it's quite unbelievable! you can't just overclock something to whatever high clock-speeds, even if you could cool it enough. Timing is one very big issue (signals need time to propagate). GB components wouldn't be able to handle these high speeds either.


Note: We can not give you the Z80 to Gameboy connection schemes via internet because it could be a High Risk Military Weapon if used incorrectly (a hacker could modify it to launch missile, like a PS2)

another prove of a fake experiment.

By Grauw

Ascended (10056)

Grauw's picture

09-01-2004, 18:26

I believe that the article is a joke. I doubt it's possible to run a 3.5 MHz CPU at 99 MHz, regardless of cooling.
The Gameboy CPU is *NOT* a Z80. It is a chip developed by Nintendo, designed after the Z80 but severely stripped down (for example it does not have the IX, IY and alternate registers, nor the block instructions). Because of this the chip's design is much simpler, and therefore it can probably be overclocked much better than a real Z80 would be. So, with a grain of salt.

Btw, I also believe the 99MHz is bullocks. Chips can be overclocked, sure, but not tens of multiples of their original speed. Especially not at a mere -10 degrees celsius...

~Grauw

By Grauw

Ascended (10056)

Grauw's picture

09-01-2004, 18:27

Also, afaik, the GB CPU runs at 1 MHz (the GBC CPU has a 2MHz mode)...

By flyguille

Prophet (3028)

flyguille's picture

09-01-2004, 18:29

the signals propagations are limited by the residuals capacities of the chip (the electric speed is nextly faster as light speed), but the residuals capacities make data loses and heat and that mark the capacities of the logics ports to react fast.

But is incredible!!!!.

By flyguille

Prophet (3028)

flyguille's picture

09-01-2004, 18:35

http://www.sorgonet.com/xtreme/gas-mask/

look that at the same url

By Grauw

Ascended (10056)

Grauw's picture

09-01-2004, 18:37

And note that in the case of MSX2 computers running at 7 or 8 MHz (6 also exists, btw), that is NO case of overclocking. At least, not of the CPU. In those computers, a Z80B (up to 6MHz) or a Z80H (up to 8MHz) is placed instead of the regular Z80A (up to 4MHz). In this case the MSX-Engine is the limiting factor, as it can not handle signals faster than approximately 10MHz. That's why there are no MSX2 computers at speeds faster than 10MHz I ever heard of. Replacing the MSX-Engine is almost impossible, as there are no 'higher speed' engines available, and no designs available as far as I know. You'd have to create your own MSX-Engine in FPGA or something, which is not a trivial task.

The TurboR @ 40MHz however *is* a case of overclocking. Ofcourse, that still leaves the matter whether that is 40 real megahertzes (the R800 runs at 7.14MHz originally), or 40 'fake' megahertzes (the R800 was advertised with a speed of 28 MHz - but that is only the relative speed compared to the Z80) (also I have heard a lot of talk of the R800 being actually 14.28 MHz for a long time, which is not true).

~Grauw

By msd

Paragon (1461)

msd's picture

09-01-2004, 20:09

The oscillater in the turbo r does run on 28Mhz, The bus speed in the turbo r is 7.16Mhz.. It the r800 runs internally on 28Mhz.. That I doen't know.

By snout

Ascended (15184)

snout's picture

09-01-2004, 20:19

IT's probably a hoax indeed, but it does make one wonder... how far can a Z80 or an R800 really be pushed? And how to keep the VDP going? With strange cooling methods and minor hardware modifications, how fast could an MSX get?

By anonymous

incognito ergo sum (116)

anonymous's picture

09-01-2004, 22:01

This is DEFINITELY a joke.

First of all, the Z80 in the gameboy is modified and not 100% compatible with normal Z80's.
Second, the CPU in the gameboy is integrated with the LCD controller and sound processor, etc... It would be impossible to use an external CPU at all, let alone an incompatible one Tongue
Third, see how there are only a few lines going from each thingy to the next? Connecting a Z80 to ANYTHING would require lines to all data lines (8) and at least some address lines (16 for a 64K system like Gameboy) and then some more..

I'm kinda disappointed a hoax like this goes on the MRC frontpage as a headline... It's not april fools, is it? :/

By anonymous

incognito ergo sum (116)

anonymous's picture

09-01-2004, 22:05

The chips used in MSX are not Flip-Chip Packaged, AFAIK that means that the core of the chip is encapsulated in that black stuff, in stead of on the outside like with modern CPU's. This means cooling has less effect, although it might help somewhat...

But do we really want a noisy computer, like a PC???

By Grauw

Ascended (10056)

Grauw's picture

10-01-2004, 17:34

No! Yay and three cheers for CF!!!