68040 mhz

[konrad]

What is the Max mhz in cpu Motorola 68040 mask L88? Its posible 50 or more. Thanks for listen

 

[finkmac]

yeah it's possible that it's 50 or more

 

[Unknown_K]

I have a Daystar 68040/40 that was modded by somebody to do over 50Mhz, but it does have a fan on the heatsink.

 

[croissantking]

I would expect a late mask 040 to do 50mhz with ease but make sure you stick a good heatsink on it.

 

[konrad]

What tool or application is reliable for determining the actual MHz?

 

[croissantking]

What tool or application is reliable for determining the actual MHz?

Newertech's Clockometer, part of the Gauge series.

 

[zigzagjoe]

I've gotten E42K and 02E31F mask chips up to 57mhz on an accelerator. L88M/K63H around the same, 55mhz being the max I recalled. Earlier masks aren't reliable much past 33mhz under ideal conditions.

That said at these speeds the 040's bus drivers are well out of spec, there's no way you will attain anything close to these speeds on a complete system bus. If you have a normal fan and heatsink on the 040, that should be enough cooling for any speed it's able to do. Accelerators mostly have small buffered high speed busses so they can go a bit further without blowing timings. If you strapped the 040 into large buffer mode (greater drive strength) rather than the default small buffer mode you might get a hair more out of it, or removing extra RAM/ROM modules to reduce bus load.

Realistically, IMO, if you can manage a stable 45mhz on an 040 Mac I'd call it good.

For 030s, much past 60mhz gets wobbly on an unbuffered accelerator and 67mhz is the utter limit on a buffered accelerator. Same issues as the 040.

 

[konrad]

I've gotten E42K and 02E31F mask chips up to 57mhz on an accelerator. L88M/K63H around the same, 55mhz being the max I recalled. Earlier masks aren't reliable much past 33mhz under ideal conditions.

That said at these speeds the 040's bus drivers are well out of spec, there's no way you will attain anything close to these speeds on a complete system bus. If you have a normal fan and heatsink on the 040, that should be enough cooling for any speed it's able to do. Accelerators mostly have small buffered high speed busses so they can go a bit further without blowing timings. If you strapped the 040 into large buffer mode (greater drive strength) rather than the default small buffer mode you might get a hair more out of it, or removing extra RAM/ROM modules to reduce bus load.

Realistically, IMO, if you can manage a stable 45mhz on an 040 Mac I'd call it good.

For 030s, much past 60mhz gets wobbly on an unbuffered accelerator and 67mhz is the utter limit on a buffered accelerator. Same issues as the 040.

Has anyone ever achieved 50 MHz or more?

 

[croissantking]

Has anyone ever achieved 50 MHz or more?

@zigzagjoe just said that he’d successfully tested up to 55-57mhz.

 

[konrad]

What were the highest MHz overclocked speeds for the 68000 and 68020? I've read about 0.30 and 0.40. Do you think Intel had better technology than Motorola? Regards