I have an old IBM PC 300GL and when I tried to start it, 5 beeps comes out, (1 long, 3 short, 1 long )...

I've tried searching for some answer on Internet but I only have found 4 beeps (1 long 3 short) so far....

Any guess what is it? I think it has something to do with the motherboard...

Please Advise...

Thanks...