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`{ r`i]'+.37@IJ"`("^Ns`X\1[t`F5r:b;>~1Z5s`X XVq`{Us`XA ( &4')w,/z5r;^?CH S l.!$5)/312)5;MAC4HnJ} R ^ b %N']-P}N#$' )Q 02I558;?CDG]HJ Mwv"#"{%(,{/146C99<ADE]J K B-! Jq" %'+-)2r57 >D"GI< H s `2 "%#& .128B;- A HGk2c $',0$3s9;8@A$BnCEJ E l 4 DeBAfu`i P# ?s`X>)]  F$C'9 <X  _$' ;# r $&% 9X 8D8 6D8$$h( 5LF!<%(*L+.2Q5i9|9>kAaD3 2#{ $<')6 /n 0  > "&y' .1.25o58p= CH/ "%a*r 0_1 8v; 8.{<./ s=U?DH-u+*ocOE#e$))],0<2b 9+BDDIC ( }#~'i4#/&%Fw%# /42m47:> @DDH1 $c S$4%&)[,.1 "0zi e $(k+. 0R6u9`>/BDtJ) !]S 6#!(*L+T-.1 6T8c:>@FHIO  KW y!&(*B/154+9F:=C FG!I S!D!$E +277T9=c@BEI& Q Z8 "m% '=+]03608v<@ADGI4  0aK   q?`2PinList--fortheCPEboard'slowerD-37connectorJ1(female).1SUA.711FPI.221BX.1431BX.52SUA.612FPI.122BX.1332BX.43SUA.513FPI.023BX.1233BX.34SUA.4145volt(1amp)24BX.1134BX.25fY.3155volt(1amp)25BX.1035BX.16fY.216FPCLK26BX.936BX.07fY.117GND27BX.837GND8fY.018GND28SelFP'9Interrupt'19GND29BX.710FPI.320BX.1530BX.6(Thepinnumbersonpage38oftheCPE-FPschematicof12/16/83aremistakenlyreversed.)Interlisp-DaccessAnaddresshereisaninteger,takenasthefivebitsSUA.4,..,SUA.7,fY.1(leastsignificant).(BX.INPUTaddress)readsa16-bitdatumfromtheaddress,returningitasaninteger.(BX.OUTPUTdatumaddress)writestheleastsignificant16bitsofdatumtotheaddress.(BX.READSTATUS)returnsthefourstatusbitsFPI.0,..,FPI.3(leastsignificant)asaninteger.NotethatBX.READSTATUSaccessestheParallelPort. fs`X hsp` bs`X`~u`i s`X:Iz) $*5u`i+s`Xu`i^s`X ]A ;u*.M;> [ ;u*.M;> Z; ;u*.M;> X ;u!"*.M;> W5 ;u!"*.M;> U ;u*.M;> T/ ;u*.M;> R ;u*.M Q) ; u*.M O ;u*.M112J2 N#LJ r!$.)j/169 ? KIHu`i  Fds`XDvs F#%W'*,8INTERMEZZO>LIBRARY>BUSEXTENDER.PRESS;2JELLINEK12-Apr-85 14:49:48