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The Rate parameterspecifieshow fast data will be arriving,measuredin
baud(namedaftertheFrenchcommunications e ngineerJean Baudot).pick
any of the followingdata transferrates:
300 baud
600 baud
1200baud
2400baud
4800 baud
9600 baud (the default)
19200baud.
Roughly, one character a second
worksoutto 11baud.
1fyou'renot sure how
fast your computer will transmit, the general rule is to cxpcrimcnt. Try
sending a page to print at the highest speed, and
workyourwaydownuntil
the pnntcr's outputlooks OK.
Serial interface: special bits
In-Serialmodeyou'llalsohave to specifyif yourcomputersendsdata bits
in groupsof seven(mostcomputerssend eight,the defaultfor a byte).
Somelimesan extra bit gets appendedto make the sum of all bits in each
characteralwaysoddor even;that'scalledparity. A paritybitcan helpspot
transmissionerrors.If yourcomputersendsthatextraparitybit,you'llhave
to say whether it produces an even or odd number of "on" bits in the
character.
You'llalsohaveto indicateif yourcomputersendstwo stopbitsto indicate
the cnd of a byte,insteadof one, the default.Theseserialintcrfaccsettings
aredcscnbedin moredetailin yourStarLaserPrinter8 Operations Manual.
Serial interface: protocol
Finally,in Serial mode your computerwill use one of three protocols to
ensure data is sent properly. Protocol (sometimes also called "handshak-
ing")means"who says what when",and is the way yourprintertells your
computerit'sreadytoreceivedata.Yourcomputerandpnntercommunicate
by sendingprotocolcontrolcodes(they'reat the frontof the ASCIItable).
Someprogrammers calltheXONand XOFFcontrolcodes"kisson andkiss
off'; otherscallthesameprotocolDC1andDC3(fordevicecontrol).Either
way,thesecodeslet yourprinterrunthe show,tellingthecomputerwhento
start and stop sendingdata. Yourprinterasksto havedata held back when
its mcmoryis nearlyfull or when it sensesan ERRORcondition.
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