yes, folks - there are still dialup users out there, and designing your pages for them is a challenge.
here are some basic rules for you to follow, and how to configure your adobe dreamweaver so that it shows the page load speed for dialup users, which is your worst-case scenario.
configuring Dreamweaver to show page download time over dialup
- start dreamweaver
- Edit, Preferences, Status Bar
- change kilobits (kbps) per second to:
- optional to include dynamically-related files (cs5 and above):
- setup a test server
- configure your dw site for a test http-ONLY server:
- edit the site in the site manager
- click on servers
- click the + to add a server
- change name to test
- change type to local/directory if server is on same machine
- set the directory by clicking on it and clicking select if it's same directory your site is in
- click advanced
- uncheck the maintain synchronization checkbox. I don't think you want it making lock files.
- change testing server to "PHP Mysql"
- click OK/DONE/whatever until you see a remote server added with the name "test".
- set "test" checkbox CHECKED and remote UNchecked ( you have to do this manually, it's the opposite by default)
- click save
- click done
- avoid the connect, get and put buttons (the plug with dot indicator, and up and down buttons)
- edit page in either code, design, or split mode and look in status bar to see "60 sec" or whatever value. this page here is 23 sec.
Emulating dialup using ethernet-style speed calculations:
the calculation to get the number 21 is as follows to translate dialup kbps to ethernet kbps:
dialup because of SS7 and fiber multiplexing is commonly going to be no more than 26.4kbps. also, 8-bit data is being converted to 10 transmission bits really, I will show you why: this is being convertted to RS-232 protocol, which differs from straight ethernet, in that the transmission is commonly 8 data bits per byte, no parity, 1 start bit, and 1 stop bit (usually people ignore the start bit and just call it 8 none 1).
8bits+1bit+1bit=10 transmission bits. this means you have 2 extra bits of overhead for every byte.
to factor in the overhead, you multiply the gross data rate (26.4kbps) by the number of data bits per byte (8) and divide by the number of transmission bits (10). you can see this 2 ways:
21.12kbps=26.4kbps×8bits/10bits or 21.12=26.4*8/10 or
some rules/guidelines for designing for dialup:
- avoid using images as much as possible.
- if you are going to use images, use a PNG with a palette or a gif, it has better compression, or a jpeg, not a PNG if you canhelp it, and use the highest compression you can and still keep jpeg lossy compression artifacts like the red/greed squares or blockiness out. png is lossless compression but by default it uses 32 or 24 bits I think and also its compression doesn't make as small a file, therefore it downloads slower.
- use CSS/CSS3+HTML5 to make your page look good.
- avoid jquery if you can, it's large. jquery is 260KiB which comes out to 260*2^10*8*10/8/26400/60=1.68 minutes worst case just to load jquery, best case is the 32kiB compressed version which comes out to 32*2^10*8*10/8/26400=12.412 seconds
calculations done with ttcalc.