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3 GB switch in Windows XP?

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3 GB switch in Windows XP?

Does anyone reading this know whether MathCad can use the 3GB memory enable switch available within Windows XP Pro? A not too distant cousin to this query would be whether or not the program has been fully optimized to manage available RAM resources when running under a 64 bit OS. Thanks in advance, Scott M.
12 REPLIES 12
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RE: 3 GB switch in Windows XP?

If you didn't get a reply over on the real forums you are not that likely to get one here. I think you can safely interpret the deathly silence and the complete lack of any documentation that would indicate any support for these features as "no" in both cases. Richard
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RE: 3 GB switch in Windows XP?

My understanding is that memory is managed by the OS, not the application. Throwing the /3GB switch in your boot.ini file should allow Mathcad to request all of the memory it wants (and will subsequently leak) up to 3 GB. I know for a fact that this is the case when using Matlab. I was going to respond over on the real forum, but it appears to be down right now. I take this to mean that PTC is henceforth restricting access to the real forum to paid maintenance customers only.
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3 GB switch in Windows XP?

anonymous wrote:

Moe Szyslak said: I was going to respond over on the real forum, but it appears to be down right now. I take this to mean that PTC is henceforth restricting access to the real forum to paid maintenance customers only.

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RE: 3 GB switch in Windows XP?

"Moe Szyslak" wrote:

My understanding is that memory is managed by the OS, not the application. Throwing the /3GB switch in your boot.ini file should allow Mathcad to request all of the memory it wants (and will subsequently leak) up to 3 GB. I know for a fact that this is the case when using Matlab.

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Re: 3 GB switch in Windows XP?

"Roger L. Mansfield" wrote:

Don't think so, Moe. I'm pretty sure Collaboratory is still open to all registered users.

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3 GB Switch?

[quote="Moe Szyslak"]My understanding is that memory is managed by the OS, not the application. Reading the Microsoft KB article on the subject led me to beleive that the executable file(s) must have certain characters appearing in its file header line. I'm not a programmer myself, and so was hoping that someone with greater knowledge in this area might know for sure. Scott M.
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Re: 3 GB Switch?

"Scott Milligan" wrote:

Reading the Microsoft KB article on the subject led me to beleive that the executable file(s) must have certain characters appearing in its file header line. I'm not a programmer myself, and so was hoping that someone with greater knowledge in this area might know for sure.

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Re: 3 GB Switch?

"Moe Szyslak" wrote:

Couldn't you simply test this? Throw the /3GB switch, reboot, open Task Manager, then open Mathcad. Type something like this: NN:0;10^100 M[NN,NN:0 Look at Task Manager and see how much memory MC gobbles up (as it preallocates the array) before crashing. Or, am I being naive?

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Re: 3 GB Switch?

"Moe Szyslak" wrote:

Also, when I tried this out, MC won't let you preallocate an array if it knows beforehand that there won't be enough memory, so you'll need to write a short program and allocate element-by-element, which is excruciatingly slow, but should still answer your question....or, not.

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3 Gb Switch

Thanks to all who responded; it sounds like I just need to try it, see what happens, and report back here (or there, as many users prefer to work in depth on the old Collaboratory). Scott M
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Re: 3 Gb Switch

I used to use the /3gb switch on very large Mathcad 15 worksheets with Windows XP SP3. It worked fine. But after installing M020 on Mathcad 15 and rebooting, I still see the normal screen display instead of the VGA display, so the /3gb switch is not working. I have another posting started on this problem in the Electrical Engineering section.

Bill

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