Path: utzoo!mnetor!tmsoft!dptcdc!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!HGRRUG52.BITNET!HOESEL
From: HOESEL@HGRRUG52.BITNET
Newsgroups: comp.sys.atari.st
Subject: deskjet pageformatter
Message-ID: <8908071137.AA00916@ucbvax.Berkeley.EDU>
Date: 7 Aug 89 12:37:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 43

I have problems with understanding the pageformatter in the deskjet firmware.
I have a deskjet plus and thought that it has a 16kB input buffer and in
addition to that a large outputbuffer (propably more then 16kB). The page-
formatter is a program in the deskjet that allows to write on random
positions to the paper (the is the same principle as with laserprinters).
However the deskjet pageformatter is memory limited: as soon as memory
fills the topline in the buffer is printed. So you cannot write completely
random to the paper, but for subscripts and superscripts emulations (as done
by some wordprocessing programs) this is a good idea.

Now here comes my problem: if the pageformatter would work correctly, then
why do some programs succeed in outputting is such a way that more then the
usual amount of ink is used in some spots. For example the laserjet driver
of wordperfect 4.1 will emulate bold characters simply by overprinting them
slightly shifted (I know that I can change this driver, and I did, so bold
characters are now printed using the deskjet internal bold fonts). What
happens is that these slightly shifted characters do overlap and produce
twice the amount of ink. These seems very strange, given the pageformatter.
It also happens many time with the epson-emulation cardrige.

Also with some programs that produce text by using the graphic capabilities
of the deskjet it happens that only a very small row of dots is printed
at a time (much less then 50, the amount that could be printed in one
stroke of the printerhead).

could someone explain this?

remark on deskjet with atari: I heard from Michael Ritzer that it was
very easy to build a bufferchip inside the cable. use the 74hct645n chip.
get the power from pin 32 of the centronics port (on the printer side of
the cable). The 74hct645n is pin-compatible with the 245, but make sure
you use the 74hct645n. This one works (I use it now, build into a small
plastic box (the one used for commercial null-modem devicec. they are
very cheap)). use the B-pins as input and the A-pins as output. this is
done by connecting the pin 'dir' and the 'enable' pin both to ground.
The voltage drop on pin 32 is at the most 1Volt and the chip keeps working
at this level. btw. pin 32 is the !error output from the printer. it is
high until a fatal error occurs (which almost never happens))

greetings,
           frans

HOESEL@HGRRUG52