The main reason for using the AppleShare Print Server is to allow many users
to print documents at the same time. A print server reduces the waiting time
by allowing several users to send documents simultaneously to be printed.
When used with a LaserWriter printer, PostScript code is sent to the print
server and then to the printer. The printer then processes this PostScript
code to produce the bit-map graphics at 300 dpi.
When printing to an AppleTalk ImageWriter printer, the computer creates and
sends the bit-map image to the printer. Creating this bitmap takes processing
time from the computer. Because the computer is having to spend time creating
the bitmap, you will not see a major difference in the amount of time it
takes to send the data to the printer or the spooler.
When printing directly to a printer, the print driver runs at an even speed
with the printer due to data transmission speeds. When connected over
AppleTalk, the network runs faster than 19,000 or 9600 baud, but the driver
has not been optimized for speed. It keeps up with the speed of the printer.
At times, the computer is waiting for the printer to finish printing the
line; other times, the printer is waiting for the computer to send and
process the line. This is why the 32K option card is not recommended for
Macintosh users.
The following table shows the amount of data that is being sent to the
ImageWriter LQ printer in all three modes. The following started as a
5.5-page AppleLink document (file size 12,648 or 13K).
Amount of data transferred to the print server or the printer:
Best Mode Faster Draft
--------- ------ -----
578K 127K 43K
The increased size of the Draft is due to AppleTalk overhead (establish
session, packet overhead). The Faster file sends out a 72-dpi bitmap in
GRAPHICS mode of the ImageWriter LQ. The Best mode sends out a 216-dpi
bitmap. This takes up more space and requires more time to send the data
to the printer or spooler. If the driver could create the 578K faster, the
print server would be able to store the data faster. However, most of the
time, the print server is waiting for the computer to send out the data.