Purely conjecture on my part, but I think last quarters bad performance (for the entire tech industry) was only a contributing factor, not a primary one. Here's why:
AMD was forced to write down Llano because it has launched Trinity and made its stock obsolete overnight. Think about it for a second... the LLano chips are NOT worthless, they just lost most of their estimated book value. Now what was the average Llano selling price? Llano launched between $50 and $130. Assuming they wrote the value down by HALF, how many $90 dollar Llano chips would it take to reach $100 million in value? How about a freaking TON.
Even if AMD zeroed out their value of Llano inventory, that is still a considerable amount of Llano silicon processors, equivalent to a years supply worth than a single quarter. $100 million write-down divided by an average $90 valuation gives an estimated 1,111,111 Llano chips... if you assume they didn't zero-out the value, then it would be even higher. This also assumes they didn't write down the value previously since launch, because hey AMD did drop Llano prices multiple times.