Wanted: 100 MHz Oscillator

[Brian Hoskins]

Rapid Electronics can supply a TTL Oscillator module which runs at 100Mhz, but it's in the 8-pin-DIL type package, not the 14-pin-DIL that you're talking about.  I've checked their catalouge and their 14-pin-DIL oscillator modules only go up to 64Mhz for some reason.  What you could possibly do is make yourself an 8pinDIL socket for the oscillator and interface it to the 14-pin-DIL that's on the board.  Or, I'm sure there are other electronics suppliers who can probably supply you with a 100Mhz TTL Oscillator module in the 14-pin-DIL package.

Before we delv into that though, I have serious doubts about the chances of this working.  If your accelerator has a 50Mhz clock but the 68030 on board is only being clocked at 25Mhz, then somewhere on the board there must be a 2:1 divisor for the clock frequency.  Most probably you can change that divisor to 1:1 and that would be a much better option.  However, since I am not familiar with your particular board I can't really comment on how or where this is done on the board.

The problem you've got is that you don't know what the clock is actually doing.  For example, the 50Mhz clock could be clocking bus speeds at 50Mhz for RAM access and things, but only clocking the 68030 at 25Mhz.  So, if you go and wap a 100Mhz oscillator in there, you'll be clocking the 68030 at a nice, safe 50Mhz but the bus speeds will be running in overdrive.  This is why finding the frequency divisor and changing it would be a better, safer option here.

What exactly is the Derringer? Is it an A500 accelerator? I'll see what I can find out on it for you.

Brian

[Brian Hoskins]

Ok what I've found out so far is that the Derringer A500 card had an optional FPU unit which could be clocked at different levels depending on the quality of the FPU you purchased.  There is a jumper on the board (JP1) which determines the clock speed for the FPU, 25Mhz or 50Mhz.

I don't know yet how you change the clock speed for the CPU, that information is not given in the manual because the Derringer only came in a 68030@25Mhz form.  I'll keep looking, we really need technical details on the board now.

Brian

[Brian Hoskins]

Hmmm, seems the Derringer was available in 50Mhz form:

"Motorola 68030 accelerator available in 25, 33, 40 and 50Mhz clock speeds.  Math coprocessor socket included."

Still looking...

Brian

[Brian Hoskins]

Ok then, you were right all along - you can indeed install a 100Mhz oscillator in the Derringer - it was done in the Platinum Version which included a 68030@50Mhz.

See this link and note the oscillator used:

http://www.amiga-hardware.com/derringer030_big.jpg

So what we need to do now is find you a 100Mhz TTL Oscillator in the 14-Pin-DIL format. I can supply you one in an 8-pin DIL format, because I have on here in my supplies, but not in the 14-pin.  I'll try some electronics suppliers for you.

Brian

[Brian Hoskins]

Ok check Farnell Electronics - they have a 100Mhz TTL DIL oscillator module but it doesn't say if it's the 8 or 14-pin package, you'll have to email them and ask the question.  Here's the link:

http://uk.farnell.com/jsp/catalog/viewproductdetails.jsp;jsessionid=42IFUOT0AAXB1QFIAEWSFE4AVAAS0IV3?prodId=101412

Also, if your current oscillator is not socketed (it's soldered in) then I would also recommend that you purchase a 14-pin DIL socket and solder that in place of your current oscillator module, so that you can swap oscillators easily at a later date if the procedeure doesn't work properly.  If you ask any decent electronics supplier for one they'll know exactly what you mean by "14-pin DIL socket".

Best of luck, and keep us updated on your progress.  If you want to do a little search and you find an electronics supplier who you think can supply what you want, but you'd rather check, then post the links here and I'll check the products out for you.

Hope I've been of help

Brian

[Brian Hoskins]

Ok, a little explanation is required on the oscillators then.
Most Amiga accelerators that I know of use either an 8-pin DIL TTL oscillator or a 14-pin DIL TTL oscillator.  The 8 or 14 pin actually reffers to the package type, but both only have 4 legs that are used.  So for example, the 8-pin DIL type will slot straight into an 8-pin DIL socket, but of course only four legs are actually used on the oscillator so the others would have no connection.

So when I say 8-pin DIL or 14-pin DIL, what we're talking about is the size of the oscillator.  The small square ones are the size of an 8-pin-DIL and the rectangular ones are the size of a 14-pin DIL.

I hope that explanation clears it up for you!!!

If you're emailing any Electronics suppliers you need to ask them if they've got a 100Mhz TTL Oscillator in the 14-pin DIL package type, and to provide you with a link to the relevant page of their online catalouge.

Brian

[Brian Hoskins]

You need to find someone who can do it for you? I assume the current oscillator is soldered in, then?

In that case I would definately recommend you order yourself a 14-pin DIL socket to go in there.  All you need to do is cut off the excess pins, leaving four outer pins and it'll drop straight in place on the board.  That will give you the opportunity of putting any oscillator you want in there at any time, which of course is a massive advantage.

In my travels earlier I found a website where a guy had overclocked his 50Mhz version to 66Mhz and according to him it works perfectly, so you could even try an even higher oscillator in there!

The job itself, fitting a socket in place of the oscilator, is not a hard one especially on your board.  If you're living anywhere near SWAUG (South Wales Amiga User Group) and you're wlling to bring your system down for us to look at, I'll even do the job for you myself.

Other than that, contact a local user group to you and see if anyone there has soldering skills.

Best regards,

Brian