#: 20137 S12/OS9/68000 (OSK)
    17-Jul-94  10:48:36
Sb: #mm2hp
Fm: LARRY OLSON 72227,3467
To:  Bob van der Poel 76510,2203 (X)


Bob,
  I have been playing around with your mm2hp program, and have been trying
to get something like it working for my 550c.
  I don't know if you are still interested in it, but I can tell you why the
screens are truncated on the right side. It appears that the HP printers are
bit based and not byte based. In other words, if you are trying to print out
a 320 x 208 screen, each line you send is 320 bytes, or 2560 bits.
  On a 8 1/2 x 11 sheet, the printer can only print 8 inches across, and at
300 dpi, it can only print 2400 dots across those 8 inches. So on a 320 horz.
screen, it will only print 300 bytes of the 320 on the line. The same problem
shows up more pronounced when you print out a 640 horz. screen. More than
half of it will be truncated.
  So it looks like the only way to print entire screens, is to do some bit
packing. If you converted each screen byte to 7 bits, and packed them into
280 bytes, for a total of 2240 bits, you would get a 7.46 inch wide print out
of a 320 screen. On the 640 screens, you would need to represent each screen
byte with 3 bits, packed into 240 bytes, for a total of 1920 bits, which
would give a 6.4 inch print out of a 640 screen.
  I wish the manuals that I got from HP would have been more informative, and
clearer on the bit verses byte for raster graphics, it would have saved me
a lot of wasted time. 
  Now I just have to come up with a good routine for packing bytes into bits.

larry

----- Larry Olson -----

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