Blizzard 1220 4mb

[paul1981]

Can somebody tells me how this fpu fits in the socket on the pic above, when this chip
 
http://www.ebay.de/itm/68882-CoPro-PLCC-FPU-Commodore-Amiga-Blizzard-Atari-/220846013303?pt=Klassische_Computer&hash=item336b72bb77
 
has many legs and the socket on the blizzard has just 4 holes?

The socket with the 4 holes is for fitting an oscillator for the FPU (for clocking the FPU at frequencies other than 14 or 28MHz). The socket above the oscillator is the FPU socket, and the PLCC FPU just slots into there (has many pins as you can see).

So for instance, the FPU you have linked to is rated at 25MHz, so you would use the jumper on the card to set the config to 28MHz.  If you wanted to push the FPU a little faster, you would have to buy a 33MHz oscillator, fit it, and jumper the card to use the oscillator you have fitted instead.

Your card should work anyway, even without the oscillator and FPU, so it's not looking good from my perspective unfortunately.
Hopefully though you will.

[paul1981]

Hi yep got it, thanks for clearing that up paul.
 
So i look at my card i have an fpu m888.. 33, so i suppose that's 33mhz. If i can get hold of an oscillator it needs to be between 33-40mhz and it will have 4 legs to fit in that socket ? The crystal is within the oscillator? (does more crystals mean more time in the crystal dome :roflmao:)
 
I am asking jacks legacy to see if they can source me one, as all they have is 50mhz, i suppose my next option would be farnell?

Just checked and amigakit stock the oscillator you need:
http://amigakit.leamancomputing.com/catalog/product_info.php?cPath=45&products_id=906

The crystal and the oscillator are the same thing, I suppose the correct name for them is Crystal Oscillator, but people tend to call them one or the other. If you do buy an oscillator, make sure you fit it the correct way, because fitting it the wrong way could easily destroy your card and the oscillator.  Same goes for the FPU.

But if you have an FPU installed already, it should still work despite their being no oscillator, PROVIDING you have the jumper set to the correct position (JUMPER D for 28MHz, or JUMPER C for 14MHz) (those frequencies are derived from the A1200 motherboard).
So set the jumper to the "D" position and see if it works.  If it doesn't work, I would try removing the FPU and see if you can get the card working without it (it's not required anyway, and used in few applications).

[paul1981]

ok thanks ,
 
so i'm waiting for the 33mhz crystal to arrive....
 
in the mean time these crystals are available:
 
http://www.amibay.com/showthread.php?t=19827
 
do you think i should get one of these 40mhz crystals as i think the blizzard 1220 can take upto 40mhz crystal oscillators.
 
Can you use a 40mhz crystal with a 33mhz fpu? Is this overclocking?
 
(incidentally i managed to track down the add4 for £29 last week so will fit that when it arrives - probably knocking out my pcmcia at the same time, ah well)

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.

Yes, 40MHz would also work for the FPU, but nothing higher. I couldn't find a 40MHz oscillator anywhere so that's why I directed you to the 33MHz one.

Please do make sure that you fit the oscillator correctly though or you are likely to see blue smoke.  Also make sure that you set the jumper correctly so that the FPU will use your new oscillator.

[paul1981]

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...

Absolutely, I'm still not entirely sure whether Snoozy got the card working without the jumpers and FPU and oscillator, he mentioned it earlier in the thread but was very vague about it.  But yes, the card should work without those parts regardless.

As for the oscillator, I've found the instruction manual for the 1220/4:
http://phase5.a1k.org/filearchive/blizzard1220_4_de_en.pdf

I've found the relevant section and quoted from the manual:

"The coprocessor can either be operated with a 14 or 28 MHz clock rate or up to 40 MHz if you use an additional oscillator. If you want to operate a coprocessor with 14 or 28 MHz then either the 14M or 28M jumper must be set (see Diagram 4).
If you want to operate a coprocessor with an asynchronous clock you must also fit a suitable quartz oscillator in a DIL-8 housing in the empty socket below the coprocessor (sec Diagrams 3 and 4). The marking on pin 1 of the oscillator must be in the bottom left comer. The EXTCLK jumper must also be set.
ATTENTION!
Only one of the jumpers 14M, 28M or EXTCLK may be set at anyone time! If two of these jumpers are set simultaneously this will cause damage to the hardware. Never set two of these three jumpers at the same time!"

So the oscillator socket is definitely for the FPU alone.  You can overclock the FPU on this card but not the CPU.

Hope this clears things up Snoozy.

[paul1981]

So I do need the 8 dil housing after all :roflmao: So does it matter which way the crystal is placed in the 8 dil socket?
 
The 1220 (without crystal but with fpu) will not work on my 1200 unless i have the jumper cover over B. Jumpers C and D i can't really get to as they look semi-blocked off?!
 
So i am thinking when i install the crystal oscillator i will leave jumpers A and B open (or jumper cover over A?) and the card should work with fpu at 33mhz and cpu 28mhz, i don't think i can change jumpers C and D, if you look at the photo earlier in the thread are jumpers C and D also look partially blocked off?

If you read the manual for the 1220/4 they don't label the jumpers anything at all, they're not labelled ABCD, they're just labelled as to their function.  Look at page 5 of the manual, you need the EXTCLK jumper connected only, no others...it's simple to see which connection you need to bridge with the jumper.
To make things simple, lets look at the photo from earlier in the thread, and label them ABCD from left to right...

What you need to do is install the oscillator correctly as per the instruction guide, make sure the FPU is seated correctly, and then use ONE SINGLE jumper in position C (next to the one that's partially blocked...the 3rd from the left if looking at the picture of the card). All jumpers do is to connect pins together...they make a circuit.

Let's clarify a bit more...
Regarding jumpers, if you look at the picture from earlier in the thread of your card, you will see that there are 2 rows of 4 pins (ABCD).
You should have 2 jumpers with your card.  The one that you say is "partially blocked" is the one on the right side (D)...well because it's only over the top pin and not the one below it as well then it is not actually doing anything - it is not making the circuit, it is not making the connection between the top right pin (D) and the bottom right pin (D)...so therefore it's OPEN, ie the jumper might as well not be there.  Infact this jumper is the DISABLE jumper and if you bridge that connection then it will turn off your card (as if the card wasn't plugged in at all)...and there's little point to that so either remove that right had jumper or just leave it over the one pin as per the picture (which is the same really as removing it).

Right, there should be another jumper.  This needs to be in position C (vertical orientation) so third from the left connecting the top and bottom rows together in column C.  That's it.
If you're still unsure Snoozy, before power on maybe you could take a photo of your card for us so that we can check that everything is okay before you power on. I wouldn't like to see the card damaged if it can be helped.

[paul1981]

So the only thing that was confusing me was the 8 dil socket, the way i read the instructions is that an 8 dil socket is used aswell as the oscillator and the 8dil socket/crystal combo is inserted into the empty socket of the 1220 with the notches in alignment. Daedalus had said that the 8 dil socket wasn't used :confused:

The socket is used for clocking the FPU (not CPU) at a frequency other that 14 or 28 MHz. You only need to put an oscillator into the socket if you want to use other (higher) frequencies than 14 or 28 MHz for the FPU (not CPU).  You have an MC68882FN33A FPU I believe, and because it's rated at 33 MHz then quite rightly you have purchased a 33MHz oscillator and yes you should use it and jumper the card accordingly to make use of your oscillator (single jumper in position C only).

I wouldn't bother overclocking the FPU because the speed increase will not be that great, the performance will still be poor when compared to the FPU built into an 040 or 060 processor, so it's not really worth buying a faster oscillator. If you do though I wouldn't go above 40 MHz, it's just not worth damaging the FPU.  Saying that though, a 33MHz rated FPU will happily run at 40MHz without problems, but it's a negligable speed increase, and of course only for applications which make use of an FPU.

Have you got the card working then?

[paul1981]

hi, but does the crystal oscillator insert directly into the 1220 empty socket OR do i insert the crystal oscillator into an 8 dil socket and then insert this 8dil socket/crystal combo into the empty 1220 socket??
 
ah just seen your reply aswell TCMSLP, so you also believe the 8 dil socket is not needed, so why does it mention using an 8 dil socket inserted into the empty socket in the instructions that Paul1981 linked to..
 
(Yep the card works fine at the moment with a jumper over B)
 
Edit: OK fitted crystal without extra 8 dil socket on consensus of opinion here and looks to be working well, let me see, sys info:
 
cpu: 68EC020 31.6mhz
fpu: 68882
comment: cowabunga
 
!!!

If you look at the speed comparison chart in sysinfo, you should be approximately twice the speed of an A2500(14MHz 68020).

You can fit the 8 PIN DIL oscillator into the 8 PIN DIL socket into the 8 PIN DIL socket already on the board if you like, but the only benefit would be that the trapdoor cover probably won't fit on any more.