Path: utzoo!attcan!uunet!oddjob!uwvax!rutgers!att!ttrdc!ttrde!ttrdf!fjo From: fjo@ttrdf.UUCP (Frank Owen ) Newsgroups: comp.sys.mac Subject: Re: HP DeskJet Drivers? Message-ID: <697@ttrdf.UUCP> Date: 11 Jul 88 23:24:30 GMT References: <6443@coherent.com> Distribution: comp Organization: AT&T, Skokie, IL Lines: 93 in article <6443@coherent.com>, dplatt@coherent.com (Dave Platt) says: > > In article <694@ttrdf.UUCP> fjo@ttrdf.UUCP (Frank Owen ) writes: > >> I have begun working on such a >> beast, but have been discouraged by the lack of documentation from Apple >> on how to do it. > > Earle Horton's articles on his daisy-wheel driver, published in > MacTutor, may be useful. > I have looked at Earle's articles, and they are helpful. Thanks Earle. > Hmmm. I have a suspicion that the speed limitation may be due to the > fact that the driver must shove a _lot_ of data over a medium-speed > serial link. At 300 dots/inch, arbitrary bit-graphics (anything that > couldn't meaningfully be compressed) would require the transmission of > 90,000 bits per square inch... at 9600 baud, that's almost 9 seconds! > I don't know what the actual interface speed is, but I'd be a bit > surprised if it's >19,200 baud. At this speed, an 8-by-10 image of > arbitrary bit-graphics would require over 300 seconds (5 minutes) to > download the bits. > Nope. The DeskJet has a compression mode that is remarkably similiar to the compression used by MacPaint when it saves bitmaps. As a preliminary exercise, I wrote a program that scales up any PICT drawing by a factor of 4. (Using Quickdraw to do the drawing into offscreen bitmaps). The bitmap is saved in compressed mode along with DeskJet printer commands. The uncompressed representation of an entire page would take 900,000 bytes, however on my test runs the compression almost always brings this down to less than 100,000 bytes of data to send to the printer. (This includes the escape sequence overhead). Additionally, the printer can receive data at 19,200 baud. On a test run, a full-page graphic image that was compressed to 90,000 bytes took about 5 minutes to print. The transmit time for the 90,000 bytes (at 19,200 baud) should be about 47 seconds. So the transmit speed is clearly NOT the problem. >I haven't studied >HP-GL, but I infer that it contain support for both compressed >graphics Actually, only the DeskJet supports this. Other HP-GL printers (like the LaserJet II) don't have a compressed mode. >(e.g. handling solid areas of black, white, or a fixed >pattern), "cursor" positioning, and perhaps some object-oriented >capabilities as well (e.g. "draw a line from point (a,b) to point >(c,d)"). The DeskJet does NOT support these due to the fact that it is incapable of assembling a page of dots and then printing it. It is a "serial" printer in that it must print the page from top to bottom in one shot. No backing up. The graphics data must be sent to the printer from top to bottom, and the printer just puts the dots down on the page, and then forgets about them. >abilities, as well as the DJ's built-in fonts where applicable, and The built in fonts would be good for draft-mode printing, where the whole page would be done using the built in fonts. Mixing the builtin fonts with the graphics is a real pain. It can be done, but the limitations enforced by the DeskJet design make it impractical. Besides, you only get one builtin font that the driver could be sure is present. You'd (I'd) have to supply bit-mapped versions of those fonts. (not a job I particuliarly want to do). In addition, you don't get rotated fonts. The built-ins are pretty much useless aside from useing them for "Draft" mode. (In this case "Draft" may actually look pretty good. The builtin font of the DeskJet sort-of looks like your typical letter-quality daisy-wheel printer. >I'm seriously thinking of buying one of these puppies as soon as my >company has some money... I'd appreciate it if you'd keep me informed of >your efforts and discoveries. You're inability to find a driver in the market (did you talk to HP?) gives me a little motivation to finish mine. What I was planning on doing was producing a driver and approaching HP with it to possibly sell them the rights to it. (I'm not particuliarly keen on marketing and producing/selling/advertising my own product- don't have the time) I will probably finish my driver in any event, and if HP goes with Cricket, then mine will most likely show-up in the public domain. -- Frank Owen (fjo@ttrdf) 312-982-2182 AT&T Information Systems Computer Systems Division, 5555 Touhy Ave., Skokie, IL 60077 PATH: ...!att!ttrdf!fjo