richard@gryphon.UUCP (12/05/87)
In article <1790@cup.portal.com> SKIBUM@cup.portal.com writes: >So whos usin a serial interface for a printer anyway. Me. For some obscure reason, the QMS PS-800 comes serial and appletalk. No parallel. Do you know what a pain it is to ship over pages and pages of PostScript at 1200 baud serial. Arrrrg! After only six months however, I was finally able to set it to 19.2Kbaud. I only had to move the thumbwheel from '0' to '1'. See Leo, you arn't the only complete moron on the net. >What do you >do when you want to use your modem? Disconnect the printer? Yes ma'am. >Spend >a hundred bucks for a switch? When they have them just SITTING THERE at work, doing nothing ? Uh-uh. :-) -- Richard J. Sexton INTERNET: richard@gryphon.CTS.COM UUCP: {hplabs!hp-sdd, sdcsvax, ihnp4, nosc}!crash!gryphon!richard "It's too dark to put the keys in my ignition..."
peter@sugar.UUCP (Peter da Silva) (12/16/87)
richard@gryphon.CTS.COM (Richard Sexton) writes: > In article <1790@cup.portal.com> SKIBUM@cup.portal.com writes: > >So whos usin a serial interface for a printer anyway. > Me. For some obscure reason, the QMS PS-800 comes serial and appletalk. > No parallel. I'm impressed. I thought serial printers went the way of the dodo. Pity, in my opinion. Why would anyone want to waste a parallel port on something so slow as a printer. I'd much rather have 2 serial ports on this baby. Speaking of babies, mine just woke up. CIAO. -- -- Peter da Silva `-_-' ...!hoptoad!academ!uhnix1!sugar!peter -- Disclaimer: These U aren't mere opinions... these are *values*.
wtm@neoucom.UUCP (Bill Mayhew) (12/20/87)
Unfortunately, much of the work that I do must be done in the land of blue pinstripes. Curiously, serveral of the more popular word processing programs expect one to attach HP laserjets via the serail port eventhough one would presume that the parallel port would be faster. If one insists on using the parallel port by redirecting the serial port, the printer will print, but the out- put will be braindamaged with margins off, underlines goofed, etc. I could see that if the printer ruminates over its data for several seconds now and then that with the parallel port, the host might think the printer went south. I agree; I think it would be nice to see an option board for the Amiga 2000 that had 3 or 4 serail ports that could exist on the Amiga side of the machine. It would be neat to make the Amiga the brain center of my house, and string serial cables to control various goodies. --Bill
peter@sugar.UUCP (Peter da Silva) (12/28/87)
In article <864@neoucom.UUCP>, wtm@neoucom.UUCP (Bill Mayhew) writes: > Unfortunately, much of the work that I do must be done in the land > of blue pinstripes. Curiously, serveral of the more popular word > processing programs expect one to attach HP laserjets via the > serail port eventhough one would presume that the parallel port > would be faster. If one insists on using the parallel port by > redirecting the serial port, the printer will print, but the out- > put will be braindamaged with margins off, underlines goofed, etc. I can't believe this. The whole world must be totally loony-tunes. First of all, conventional printers (a slow device) typically come with a very fast interface that they can't even begin to take advantage of, but restrictes them (theoretically) to within 6 feet of the computer. Then a laser-printer (a fast device) is forced by a bunch of brain damaged programs to use the slower RS232 interface, even though it's perfectly capable of taking advantage of any data rate you care to ship it. Also, since it's usually not run unattended it wouldn't matter if it was forced to be close to the machine. I have no idea how things like this happen. It's a wonder that anything ever comes out un-fubar. -- -- Peter da Silva `-_-' ...!hoptoad!academ!uhnix1!sugar!peter -- Disclaimer: These U aren't mere opinions... these are *values*.
farren@gethen.UUCP (Michael J. Farren) (12/29/87)
In article <1325@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes: >First of all, conventional printers (a slow device) typically come with >a very fast interface that they can't even begin to take advantage of, but >restrictes them (theoretically) to within 6 feet of the computer. Which is that? I've operated Centronics parallel interfaces over 50' cables with no problem (although I admit this is stretching it a bit - 20' should be no problem whatsoever.) >Then a laser-printer (a fast device) is forced by a bunch of brain damaged >programs to use the slower RS232 interface, even though it's perfectly capable >of taking advantage of any data rate you care to ship it. Also, since it's >usually not run unattended it wouldn't matter if it was forced to be close to >the machine. The reason serial interfaces are forced is much more likely to be because the original 'affordable' laser printer, the HP LaserJet, did not HAVE a parallel interface - it was serial or nothing. Likewise, the Apple Laserwriter also is serial-only. Don't blame the software guys for something the hardware guys almost forced them to do. I do agree - it's a wonder, all right... -- Michael J. Farren | "INVESTIGATE your point of view, don't just {ucbvax, uunet, hoptoad}! | dogmatize it! Reflect on it and re-evaluate unisoft!gethen!farren | it. You may want to change your mind someday." gethen!farren@lll-winken.arpa | Tom Reingold, from alt.flame
dillon@CORY.BERKELEY.EDU (Matt Dillon) (12/30/87)
:In article <1325@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes:
:>First of all, conventional printers (a slow device) typically come with
:>a very fast interface that they can't even begin to take advantage of, but
:>restrictes them (theoretically) to within 6 feet of the computer.
:
:Which is that? I've operated Centronics parallel interfaces over 50'
:cables with no problem (although I admit this is stretching it a bit -
:20' should be no problem whatsoever.)
A couple of things to note here:
(1) Centronics is syncronous, meaning that every byte is handshaked.
At 50' it will go quite a bit slower and much less reliably than
at 5'. However, since printers are notoriously slow anyway one
usually doesn't see the difference. A similar unshielded and
undriven serial cable would not be able to go quite as fast.
(2) Beyond popular belief, serial is NOT slower than parallel! That's
right! Consider that serial is just two lines (not including
ground)... very easy to make into a twisted pair, shield, connect
to power drivers, or place on a carrier. I've seen serial over
a cable TV channel at 56KBaud, and we weren't even trying! Of
late we've had RS422 which utilizes balanced lines and can go even
faster than RS232.
Example: Bryce created a product for the C64 to speed up the
C64<->1541 interface. He simply connected an extra serial line on
an IO chip between the two running at (almost) the crystal frequency.
Without trying he almost beat out my PET<->2031 interface which was
using synced microprocessors over a parallel line (read: no
handshaking).
The moral of the story: You can make a serial interface sooo fast that
you don't even have to worry about 'waiting' for the character to be
sent... the interface is faster than the fastest you could shove it
out from a lowly 68000.
-Mattgrr@cbmvax.UUCP (George Robbins) (01/03/88)
In article <8712292114.AA22022@cory.Berkeley.EDU> dillon@CORY.BERKELEY.EDU (Matt Dillon) writes: > :In article <1325@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes: > :>First of all, conventional printers (a slow device) typically come with > :>a very fast interface that they can't even begin to take advantage of, but > :>restrictes them (theoretically) to within 6 feet of the computer. > : > :Which is that? I've operated Centronics parallel interfaces over 50' > :cables with no problem (although I admit this is stretching it a bit - > :20' should be no problem whatsoever.) > > A couple of things to note here: > > (1) Centronics is syncronous, meaning that every byte is handshaked. > At 50' it will go quite a bit slower and much less reliably than > at 5'. However, since printers are notoriously slow anyway one > usually doesn't see the difference. A similar unshielded and > undriven serial cable would not be able to go quite as fast. > > (2) Beyond popular belief, serial is NOT slower than parallel! That's > right! Consider that serial is just two lines (not including > ground)... very easy to make into a twisted pair, shield, connect > to power drivers, or place on a carrier. I've seen serial over > a cable TV channel at 56KBaud, and we weren't even trying! Of > late we've had RS422 which utilizes balanced lines and can go even > faster than RS232. EEK! More confusion in the form of true, but marginally relevant facts. You can have a "long" Centronics cable. The length is basically limited by the characteristics of the driving and receiving circuits, the cable characteristics, the number of grounds connected and the hardware/software timing. Centronics is a parallel interface. You put out the data, allow time (deskew) for all the bits to get to the receiving end, and then send a strobe telling the printer that the data is there. The printer eats the data and sends back busy/acknowledge signals. This is all spec'ed to work over maybe a 10-15 foot cable. It fails if: a) the deskew delay isn't long enough for the data to have settled b) the strobe or ack pulses are degraded by the cable characteristics c) there is a grounding problem between the two machines d) there is electrical noise or ringing on the data or strobe/ack lines "Real Computers" offer special "long lines" interfaces with appropriate timing, circuitry and cabling to avoid these problem. Micro users get the generic flavor and your milage may vary. As for whether serial or parallel is faster, remember than the following crude approximation holds: characters/sec = lines/minute = bits-second/10. For the typical serial printer (with a line buffer) anything over 2400 bps is likely to be wasted. For laser printers, especically in bit gulping graphics modes, it's a different story, but remember that your computer isn't a CRAY-7 and a 19.2Kbps serial line is probably quicker than your computer can generate (although perhaps not dump from a file) real data. Since the "centronics" interface is shoving 8 bits in parallel, you could assume a 10 microsecond best case output loop, giving the equivalent of a 1-megaBPS async serial line, but as pointed out above, this is pretty much academic... -- George Robbins - now working for, uucp: {uunet|ihnp4|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@uunet.uu.net Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)