BUSEXTENDER--BusExtensionPortfor1108withExtendedProcessorOption(CPE)Initiallyreleased:17Sept1984MichaelHerringAuser-designeddevicecanbeattachedtoan1108withExtendedProcessorOption(CPE)throughthesameconnectorthatXerox'sPC-busandMultibusadaptersuse.Thisdocumentdescribestheprotocolforthisconnector,andbasicInterlisp-Dfunctionsforaccessingit.TheBusExtender(BX)connectorallowstheDandyTigertoread&/orwrite16-bitwordsatanyof32register-addressesontheexternaldevice.Four1-bitstatuslinescanalsoberead.Aninterruptlineisreservedforusewithfuturemicrocode.ThemaximumdatatransferratewhenthedeviceisaccessedfromtheInterlisp-Dfunctonsbelowis150Kwords/second.Bursttransferratesof2Mwords/secondcanbeachievedwithspecializedmicrocode.TheBXconnectoristheDandyTigerCPEboard'slowerD-37connectorJ1(female).Itisnotcabledtotheoutsideofthe1108.DescriptionofsignalsonconnectorBX.0-15Data.Bidirectional.BX.15leastsignificant.SUA.4-7Address(withfY.1).SUA.7leastsignificant.fY.0Direction.1=fromdevicetoprocessor.fY.1Address(withSUA.4-7).fY.2-3Deviceselect(withSelFP').SelFP'Deviceselect(withfY.2-3).Activelow.FPCLKClock.Normallyhigh(98msmin),39nslow,risingedgeactive.AlwayshighwhenSelFP'=1.FPI.0-3Statuslines.Asynchronousinputtoprocessor.Interrupt'Interrupt.Asynchronousinputtoprocessor.Activelow.Thecurrentmicrocodeversiondoesnotsupportthisexternalinterrupt,soInterrupt'mustnotbeasserted(pulleddown).SignalsareTTLactivehighexceptasstated.Sincethesearehigh-speedintra-processorbussignals,thecablemustbeshort,e.g.2feet.TheexternalBXdeviceisselectedwhenfY.2=fY.3=SelFP'=0.WritingtotheregisterwithaddressSUA.4-7=fY.1=0mustnothaveanysignificanteffect.Suchwritesaregeneratedbythecentralprocessorasasideeffectofotheroperations.Withspecialcabling,theuserdevicecouldsharetheBXconnectorwithXerox'sPC-busorMultibusadapters.Thentheregister-addresseswithSUA.4-7=2and3arereservedfortheXeroxbusadapters,asisthestatuslineFPI.1.TimingrequirementsontheBXdevicewillbeincludedinlaterversionsofthisdocumentation.Thewrite-to-devicecycleisstraightforward.TheDandyTigermicrocodeassumesthatreadsfromtheBXdevicearepipelinedovertwoBXcycles;thatis,thatthedatumreturnedfromtheBXdeviceduringareadcycleisthataddressedinthepreviousBXcycle. q?` p  q?` g_p aq arae$'+.37@IRIRa"`(-`"^Ns"^N"\"\1[t5z:j;>A[1Z59ZsZ9Z X XVqVUsI 0 &<'),/5z;f?CHHU S %t6!$=)/;1215;UA C<HvJJS R f j %V'e-.HRP}P}N #,'()Y 02Q5=8;?CDGeHJJN Mw~"+"%(,/146K99< AD'EeJJMw K J5) KJq"(%'+-12z57 >D*HIDIDJq H { h:"-#& .128J;5 A HHHGk:k $',0,3{9;@@A,BvCEJ$J$Gk E t <E De De B B Afu X##"Af ?s ? >)e  N$K'A ->) <`  g$' .< ;# "z $.% +;# 9`"Q9 8L@#8 6L@$$p(+6 5TN!D%"(*T+.2Y5q99>sAiDD533 2+ $D')> /v/|2 0  F #&( .9.25w58x=CH"H"0/ "%i*z 0g1 8 8 / v/ ;(8 .=.=/ s/ =]? D'HH/ -u-u++*okWM#m$) )e,0D2j 93BLDIKIK*o ( %+('i<#7&4'i%N-# /<2u47:F @DDH9H9% $c [$<%&)c,.1 8x$c"8q m $(s+.0Z6}9h>7BD|J1J1" !][ >#)(*T+\-.16\8k:>@FHIWIW!]  %SW !& (*J/1=439N:=K FG)IIW [!L!$M +2?7\9=k@BEI.I. Q b@ "u%'E+e04688~<@ADGIA]A [ C}+.U;>A[ Z; C}+.U;>AZ; X C}!"+.U;>AX W5 C}!"+.U;>AW5 U C}+.U;>AU T/ C}+.U;>BNT/ R C}+.U27R Q) C }+.U1PQ) O C}+.U112R22O N# N#L R z"$6)r/169 ? EL K K I I Hu H Fds FdDDvDEDsD N#%_'*,9LIBRARY>BUSEXTENDER.TEDIT;1JELLINEK 1-Dec-84 15:58:23