Internal Memo XEROX To From June87 Interest Rick Barth PARC-CSL Subject Date June87 Logic Diagrams July 24, 1986 Introduction This document describes the structure of the machine above the responsibility of individual designers. Issues Arbitration My theory on arbitration is that there is a line which does more or less the same thing as a data line which says no new memory requests. It is generally only pulled by a memory module when its FIFO might fill up. No more start packets may be issued while this line is asserted. The request/grant lines are statically allocated to the board slots. 4 to io/display, 4 to memory and 8 apiece to the other three slots. One io/display is lowest priority, one is highest priority, all the others are round robin in between. Serial Debug Bus What should such a bus look like? Presumably we are now constrained by what the EU and IFU implement. Bipolar and ECL Why aren't the bus interface and buffer chips bipolar gate arrays using ECL levels? Then we could probably put the clock generator in the bus interface chip and the miscellaneous buffers in the bus buffer chip. Power Processor - 40 + Terminators - 15 => 55 /processor board Backplane termination => 10 Memory board => 100 Disk drive => 25 I/O board => 35 Display controller => 20 Fans => 10 Basic board set total - 260 Another processor board => 55 Another memory board => 100 Total - 415 @ 70% power supply efficiency => 600 Plus 200 watt color monitor. bStyleDefBeginStyle (Cedar) AttachStyle (firstHeadersAfterPage) {0} .cvx .def (root) "format for root nodes" { FontPrefix docStandard 36 pt topMargin 36 pt headerMargin .5 in footerMargin .5 in bottomMargin 1.75 in leftMargin 1.5 in rightMargin 5.25 in lineLength 24 pt topIndent 24 pt topLeading 0 leftIndent 10 pt rightIndent } StyleRule (positionInternalMemoLogo) "Xerox logo: screen" { docStandard 1 pt leading 1 pt topLeading 1 pt bottomLeading } ScreenRule (positionInternalMemoLogo) "for Xerox logo" { docStandard 1 pt leading 1 pt topLeading -28 pt bottomLeading -1.5 in leftIndent } PrintRule (internalMemoLogo) "Xerox logo: screen" { "Logo" family 18 bp size 20 pt topLeading 20 pt bottomLeading } ScreenRule (internalMemoLogo) "for Xerox logo" { "Logo" family 18 pt size 12 pt leading -28 pt topLeading 36 pt bottomLeading -1.5 in leftIndent } PrintRule (memoHead) "for the To, From, Subject nodes at front of memos" { docStandard AlternateFontFamily 240 pt tabStops } StyleRule EndStyleIblockMark insideHeaderbox IpositioninternalmemologoIinternalmemologomemoheadsNt N NNNNN N##NNhead Ibodyf PPPfPP8PPPPPP PPPP P$P *