Path: utzoo!attcan!uunet!mcsun!unido!gmdzi!strobl From: strobl@gmdzi.UUCP (Wolfgang Strobl) Newsgroups: comp.sys.mac.misc Subject: Re: Windows/Mac flame war fuel Message-ID: <3040@gmdzi.UUCP> Date: 5 Jul 90 14:07:51 GMT References: <8974@goofy.Apple.COM> <2988@gmdzi.UUCP> <7729@jarthur.Claremont.EDU> Organization: GMD, Sankt Augustin, F. R. Germany Lines: 44 wilkins@jarthur.Claremont.EDU (Mark Wilkins) writes: >In article <2988@gmdzi.UUCP> strobl@gmdzi.UUCP (Wolfgang Strobl) writes: >>This either implies that the printer driver can query the printer about >>the resources (memory, fonts, resolution, paper size, ...) it has >>available - which is not possible on monodirectional links -, or it >>restricts the printer driver to worst case asumptions. > Actually, printers on the Mac are connected to a serial port which is >bidirectional. If the printer is out of paper, for example, the Mac itself >alerts the user that the printer is not ready to print and that perhaps >paper has not been loaded. > Are one-way printer connections the norm in the MS-DOS world? In a way. The most popular interface is the Centronics type parallel interface. It is faster than the usual serial links, because it transports data a byte at a time, not a bit at a time. It has a monodirectional 8-bit data channel, and control lines in both directions. There is a reset line going to the printer, and the printer can report out of paper, busy and general error conditions back to the computer on separate lines. The whole design is quite bulletproof, cheap and requires nearly no protocol between printer and computer. Its disadvantages are: limited cable length and no data channel back to the computer. (On IBM's PS/2 machines the parallel port is bidirecitonal, but I don't know any printers which have a bidirectional Centronics type interface). So this interface can do what you gave as examples of a bidirectional link, too. But it is not possible for a printer to report things like "I don't have font yxz" or "I have the following fonts installed" back to the computer. Let me restate my question. Does a Macintosh printer driver query the printer about such things, i.e. what font cartriges are installed, whether the paper is in to upper or in the lower reservoir, how much memory it has installed, which paper size is loaded ...? If not, how does a printer driver get this information, if there is no configuration necessary? Wolfgang Strobl #include