Blizzard 1220 4mb

[Daedalus]

A quick look at the Amiga Hardware site shows that jumper B is for switching between internal and external oscillators. That being the case, unless you have an external oscillator on the board (usually a square or rectangular shiny metal block with the frequency written on it) then it won't work with that setting.

The Amiga-Hardware website is a great resource, but it uses frames which make it tricky to link to information. Looking at the photo though, it appears there's an empty socket in the centre of the board for the crystal, just above and to the left of the clock battery. Does your board have this too?

[Daedalus]

But that makes sense when you think about it. With the cover over B it's using the motherboard clock to run the CPU, with the jumper open, it's trying to use the oscillator on the card - but there's none there, just an empty socket. With no oscillator clock signal the CPU simply cannot run, giving you the errors you're seeing. You could buy a crystal from an electronics supplier and use it, but I doubt it's worth your while...

[Daedalus]

Just for clarity: Without the crystal, and with the jumper set to take the clock signal from the motherboard, the CPU should still work on the Blizzard. Fitting the crystal and using it instead will make the CPU (and FPU) run at the crystal's frequency instead. As Paul pointed out, be very careful of fitting it around the correct way. The FPU should only fit one way, but the oscillator can fit 4 ways, and only one is right. It should just plug into the socket though, you won't need to solder it.

Edit: The orientation should be marked on the board, you can't assume it's just upright. There will be one corner on the crystal that's different to the other 3 - sometimes it has a dot printed on the case, sometimes a different shape of the metal container on that corner. This corner should be marked on the board some way or another. If it's not, I would say that the marked corner goes with the notched corner of the socket (pin 1) which can be seen to the lower left of the socket in the photo further up in this thread. Hope that makes sense!

Also, just for pedantics, the crystal oscillator is actually a small circuit, containing the crystal itself and some other components needed to make a clean, square-wave clock signal.

[Daedalus]

Sorry, I think there's still a little bit of confusion here... The oscillator/crystal combo is all-in-one, so you just have to get that module and put it in the socket on the board. There aren't any other sockets involved. It'll look something like this:



You can see the dot printed on the top at the bottom left corner - this is the "pin 1" which tells you what way around to put it. Just plug it into the socket on your board (the right way around!) and you're done. Sorry if I made things a bit more confusing there

[Daedalus]

The sockets they sell are for adding to a board which doesn't already have one... Most accelerators use their own crystal oscillator instead of the motherboard one, and so have the crystal permanently soldered in place. If you have the skill and tools, you can desolder the crystal and solder one of those sockets in its place, thus allowing you to change crystals more easily. This means you can overclock your CPU simply by swapping out the crystal.

Your board is a little different, in that the crystal is optional, and therefore came with a socket from the factory instead. I don't know how much it's worth upgrading, but the crystals are relatively cheap so no harm in trying it out. To max out the RAM you need the custom memory add-on - I've never seen one and I'd imagine they're fairly rare (and therefore expensive). Unless you find you need it, I wouldn't worry about it. You could probably do just fine without it.

[Daedalus]

Yeah, it'll most likely make the PCMCIA unusable alright, but no harm to have for that price really - it's not as expensive as I thought it'd be. Yes, using a faster crystal than that which the chip is designed for is overclocking. Be careful with that, too much overclocking can shorten the lifespan of the chips or result in an unstable computer. Since the CPU on that board is rated for 28MHz, I'd imagine 33 would be fine, but 40MHz is probably pushing it a bit. By all means give it a try, chances are you wouldn't do any permanent damage with a short test, but be aware of the risks and keep an eye on the chips to make sure they don't get too hot.

[Daedalus]

Surely the oscillator if fitted is just for use by the FPU and not the CPU?  That's how it works on standard ram expansion cards with FPU's.  In that case all you would be doing is overclocking the FPU, so once you fit your 33MHz oscillator the FPU will be clocked at 33MHz whilst the CPU always remains at 28MHz.

But then why won't the card run when there's no oscillator installed? If the CPU ran off the motherboard clock then surely it wouldn't matter which way the FPU was set when there's no FPU installed? The memory's gonna run off the CPU's clock anyway - it doesn't need it's own clock...