*.dwg file size curiosity.

[austim]

Hi, all.

This is not an earth-shattering deeply technical problem, but it has the potential to keep me awake at night. I am hoping that someone can give me a logical explanation for something I observed just now.

I opened a drawing - call it "Rev1.dwg". Win Explorer tells me it is 270 kB.

Without altering anything on it, I immediately saved it as "Rev2.dwg" via the "Save as" button. At that stage Win Explorer told me it was now 272 kB.

I reopened "Rev2.dwg" and immediately saved it as "Rev2.dwg" again (overwriting the existing file). Win Explorer now tells me it is 274 kB.

ie it appears that every time I go through the "Save as" routine, I add 2 kB to the file.

Why would that be??

 

[Qshake]

Well, I'm not one hundred percent sure, but when I began to lose the ink and join the computer revolution I took a class on CAD (CADKEY, I seem to recall) and all the commands were key entry on one screen and the drawing was done on another....to make a long story short...I beleive that the "commands" were saved as part of the drawing file. Today those icons or buttons are just a way to envoke a line of commands so what is probably happening is that those "save as" commands are being processed and stored within the file.

Anyone else??

 

[kmacsys]

I also notice the same thing when I open and close dwgs. When you do a "saveas" the filename gets changed, and since a hard drive has "sectors" typically the filesize will change when you save it under a new name. If you save it under the same name, it probably will also add 2-4K due to the "time keeper" in ACAD (type in "status" at the ACAD command prompt and you will see the total time on a dwg, this changes EVERY time you open and close a dwg). Also, if you change the zoom and then save it will change the filesize as the file retains the zoom parameters in the CADD file. Remember to use the "Purge" command to clean out files and minimize filesize by erasing unnecessary fonts, layers, blocks, and dimension styles. DON'T LOSE SLEEP OVER THIS ONE...for life is too short...

 

[AJUK]

I think its a throwback from DOS. Most other CAD systems, designed specifically for Windows, do not carry such baggage and generally have much smaller file sizes than AC for the same drawing.

 

[austim]

Qshake, kmacsys, AJUK,

Thank you all for your help. I don't use ACAD very often, and had been presuming that I was doing something stupid. (That still remains another possibility, of course).

It just seems to me that adding 2kB each new "save as" is a bit excessive. I will try the purge command - that sounds very promising.

Having started my computing days well before DOS, today's gross use of memory still offends me. I recall doing useful stuff (eg analysis of a general 2D arch under variable local loads) with a machine that had a total of 120 bytes of addressable memory. We had to give that up when we couldn't get the rubber drive bands any more.