### Dave Northey's Blog

• #### Issue in Excel 2007 (and Excel Services 2007) involving calculation of numbers around 65,535

Yesterday we were alerted to an issue in Excel 2007 (and Excel Services 2007) involving calculation of numbers around 65,535.  The Excel team would like to provide a description of the issue and explain what we're doing about it.

Background
Yesterday evening we were alerted to an issue in Excel 2007 (and Excel Services 2007) involving calculation of numbers around 65,535.  The first example that we heard about was =77.1*850, but it became clear from our testing as well as additional reports that this was just one instance where Excel 2007 would return a value of 100,000 instead of 65,535.  The majority of these additional reports were focused on multiplication (ex. =5.1*12850; =10.2*6425; =20.4*3212.5 ), but our testing showed that this really didn't have anything do to with multiplication - it manifested itself with many but not all calculations in Excel that should have resulted in 65,535 (=65535*1 and =16383.75*4 worked for instance).  Further testing showed a similar phenomenon with 65,536 as well.  This issue only exists in Excel 2007, not previous versions.

The Problem
This issue was introduced when we were making changes to the Excel calculation logic in the Office 2007 time frame.  Specifically, Excel incorrectly displays the result of a calculation in 12 very specific cases (outlined below).  The key here is that the issue is actually not in the calculation itself (the result of the calculation stored in Excel's memory is correct), but only in the result that is shown in the sheet.  Said another way, =850*77.1 will display an incorrect value, but if you then multiply the result by 2, you will get the correct answer (i.e. if A1 contains "=850*77.1", and A2 contains "=A1*2", A2 will return the correct answer of 131,070).

So what, specifically, are the values that cause this display problem?  Of the 9.214*10^18 different floating point numbers (floating point on wikipedia) that Excel 2007 can store, there are 6 floating point numbers (using binary representation) between 65534.99999999995 and 65535, and 6 between 65535.99999999995 and 65536 that cause this problem.  You can't actually enter these numbers into Excel directly (since Excel will round to 15 digits on entry), but any calculation returning one of those results will display this issue if the results of the calculation are displayed in a cell.  All other calculation results are not affected.

The Solution
We take calculation in Excel very seriously and we do everything we can in order to ensure that calculation is correct for all cases.  We've come up with a fix for this issue and are in the final phases of a broad test pass in order to ensure that the fix works and doesn't introduce any additional issues - especially any other calculation issues.  This fix then needs to make its way through our official build lab and onto a download site - which we expect to happen very soon.  We'll add another post once that's taken place with a link to the download.

Dave

• #### Windows Server 2008 RC0

So, yesterday at the re-delivery of August's Longhorn Academy (and at lest weeks session) I mentioned that we'd be shipping Release Candidate Zero (RC0) of Windows Server 2008 soon.  Well soon=today.

Enjoy,

Dave.

• #### My actions from yesterday's Longhorn Academy

Firstly, thank you to all who attended - I really enjoyed the event (even the feedback)!

I'm getting ALL the PowerPoints from ALL the sessions posted to one place (they're currently all over the place).  I'll email a link to them (and post it here) when I have it.

All the Hands on Labs are here (TechNet Virtual Labs).

I'm going to send you all an email to see if you're interested in some "online noise".

And lastly, to get EasyPrint working for XP, you need this (beta) download.  You actually need the RDP 6.0 cliend ant version 3.0 of the .NET framework.  XP Service Pack 3 will be the only supported solution when we ship.

Thanks again, and expect an email from me early next week..

Dave.

• #### IT Pro Security Training Event (Dublin)

Microsoft Ireland is running a day of Security training for IT Professionals on October 11th.  You can find out more and register for it here.

We're also running a day or Security training for Developers on October 12th.  You can find out more and register for it here.

I've got a 90 minute slot in the morning of the 11th - covering off a potted history of Microsoft and Security and explaining our progress and where we're up to.  I'll also get do do a few demos of security features in both Windows Vista and Server 2008.

Hope to see you there,

Dave.

• #### Windows Server Virtualisation (Public Technology Preview).

I've been talking about and showing you Windows Server Virtualisation (WSV) for a good while now (it's our new Hypervisor based Virtualisation solution coming out with Windows Server 2008).

Well, the cat's out of the bag now - you'll all be ably to 'play' with it as soon as the next public beta of Windows Server 2008 ships (Release Candidate Zero is due out very soon) - it will include the first public technology preview of Windows Server Virtualisation.

Inside Microsoft, we've all known this for a while and have been asked to keep it quiet.  Larry Orecklin (general manager of marketing for System Center at Microsoft) let it slip in an interview he had on Presspass the other day.

I have to give all credit for highlighting this to my friends over in Canada, who got there first yesterday on their IT Pro Connection blog.

Since then, I've been beaten to it yet again by Keith Combs - who has managed to get a 10 minute screen cast (showing off WSV) up on his site before me.  Ah well..

Enjoy,

Dave.

• #### IT Pro Momentum

I've had a few questions about the IT Pro Momentum offer I called out the other day.

Send me an email if you're interested in learning about Windows Server 2008 and/or SQL Server 2008 (and you're based in Ireland).  As long as you 'fit the bill' I'll get you an invite to the IT Pro Momentum portal (that we'll be launching soon).  You'll get to profile yourself and your project (evaluating Windows Server 2008?).  As your project moves along from Evaluate, through Plan and Pilot, you'll get the free support detailed below:

And as soon as you're ready to share your experiences with the wider community, let me know and I can help you make that happen (include you in our TechNet newsletter, post details about you on my blog, help you find an attentive audience to listen to you, whatever).

Thanks,

Dave.

• #### BSS events this Wednesday and Thursday

There was a lot of interest in the video I showed yesterday in Dublin and on Wednesday in Belfast.  You can find the video online here.

If you're interested in 'playing' with some of the technologies shown, you can find PhotoSynth here (there's a little application to install) and it works in both IE and Firefox.  You need to be running Windows XP SP2 or Windows Vista and you need a fairly decent graphics card (one that's capable of running DirectX 9).

You can play with loads of Interactive Visual Media examples here - including the High Definition Gigapixel Panoramas.  Have a look at the 3.7 GPix picture of Downtown Seattle and see if you can find the Owl (I finally found it whilst looking for the links for this post - probably couldn't find it again though)!

Have fun,

Dave.

• #### Friday's Security Nugget.

So today I'm trying something a bit different.  Working in the Developer and Platform Group, I'm surrounded by developers - and they really like Silverlight (a framework for developing high-quality, cross-platform, cross-browser, media-enabled rich interactive web applications).

If you like this format, I'll do a lot more (it was actually good fun putting this together).

So, I've been running something called the 'Longhorn Academy' for the last four months - 130 IT Pros in a room for half a day, once a month to learn Longhorn (Windows Server 2008).  One of the topics included a detailed, deep-dive into Network Access Protection (NAP), something that I think is probably one of the best new features coming with Windows Server 2008.

NAP enables IT administrators to enforce network access policies.  It's not really a security product, as you could use it to enforce an un-secure network, but combined with very secure policies it will help greatly with security.

At a very high level, NAP lets me decide what a compliant PC 'looks like' (must have a firewall turned on, must have an up-to-date anti-virus product installed, etc).  Then it only allows full network access to those PCs that are compliant with that policy.  Any machine that is not compliant will either be kicked off of the network, or given limited access to a part of the network where they can fix the problem (get an up-to-date anti-virus signature, download a patch, etc).

Methods of NAP include DHCP, 802.1x, VPN and IPSec.  This demo is IPSec, but they all offer the same basic functionality.

Enjoy

I've posted this on youtube as well (just incase you're running Linux & can't run Silverlight - yet).

Dave.

• #### System Center Virtual Machine Manager 2007 is here

OK, looks like I was just a bit premature.  All the official sites are now up-to-date.  SCVMM pages on Microsoft,com and the official Windows Virtualisation blog.

We've announced four things:

1. Public availability and general availability in October.
2. Pricing and Licensing
3. A Workgroup edition
4. Future directions for SCVMM

Number 4 is interesting - obviously we'll be adding support for Windows Server Virtualisation (when it ships), but we're also adding support for VMWare and Xen.

Dave.