// BFS.DEF structure [ wordAddr bit 12; bitAddr bit 4 ] manifest [ msb=#100000 ] manifest lFID=3 // disk data structures, transcribed from osstructures // page 1 locations manifest [ nextDiskCommand = #521 // pointer to DCB diskStatus = #522 // @DS lastDiskAddress = #523 // @DA sectorInterrupts = #524 ] // disk address structure DA[ sector bit 4 track bit 9 head bit 1 disk bit 1 restore bit 1 ] // disk header structure DH[ packId word diskAddress @DA ] // disk label. *=set by DoDiskCommand structure DL[ next word // disk address of next file // page, or eofDA previous word // disk address of previous // file page, or eofDA blank word numChars word // between 0 and charsPerPage inclusive. // ne charsPerPage only on last page pageNumber word // * leader is page 0, first data // page is page 1 fileId word lFID // * ] manifest lDL=size DL/16 // disk status word. See hardware manual for detailed definitions structure DS[ sector bit 4 done bit 4 seekFailed bit seekInProgress bit notReady bit dataLate bit noTransfer bit checksumError bit finalStatus bit 2 ] // disk command structure DC[ seal bit 8 // must be #110 headerAction bit 2 labelAction bit 2 dataAction bit 2 seekOnly bit 1 exchangeDisks bit 1 // disk controller inverts // DCB.diskAddress if this bit // is set ] manifest diskCommandSeal=#110 // possible disk actions in command word manifest [ diskRead = 0; diskCheck = 1; diskWrite = 2] // disk command block. *=set by DoDiskCommand, $=defaulted by // DoDiskCommand if 0 structure DCB[ nextCommand word // * status @DS // set when command is completed command @DC // * headerAddress word // * these are memory addresses labelAddress word // $ dataAddress word // * normalWakeups word // $ errorWakeups word // $ header @DH = [ blank word diskAddress @DA // * if DA argument ne fillInDA ] ] manifest lDCB=size DCB/16 // *=initialized by InitializeCbStorage; everything else is zeroed structure CBZ[ length word // * DAs word cleanupRoutine word currentDA word currentPage word // * set only by InitCbStorage currentNumChars word normalWakeups word errorWakeups word errorCount word errorRoutine word extra word queueHead word // * address of first entry queueTail word // * address of last entry + 1 endQueueVec word // * address of first word beyond queueVec ^ 0, 1000 word // * contains one more entry than // there are cb's in the zone ] manifest [ lCBZ=offset CBZ.queueVec/16+1 CBZqueueHead=offset CBZ.queueHead/16 CBZqueueTail=offset CBZ.queueTail/16 ] // *=initialized by InitializeCbStorage; everything else is zeroed structure CB[ // the DCB must come first @DCB // a free CB must have // status=DSgoodStatus; // initialization leaves it // that way label @DL truePageNumber word // 'variable' part of the cb ends here zone word // * retry word // * ] manifest [ lCB=size CB/16; lVarCB=offset CB.zone/16 ] // normally we want room for 3 cb's in a zone manifest CBzoneLength=lCBZ+3*(lCB+1) manifest [ DSerrorBits=msb rshift offset DS.seekFailed + msb rshift offset DS.notReady + msb rshift offset DS.dataLate + msb rshift offset DS.checksumError + (-(msb rshift (size DS.finalStatus-1))) rshift offset DS.finalStatus; DSdoneBits=(-(msb rshift (size DS.done-1))) rshift offset DS.done; DSgoodStatusMask=DSerrorBits % DSdoneBits; // good status means that all the error bits are 0 DSgoodStatus=DSdoneBits DSfreeStatus=msb rshift (offset DS.done+size DS.done-1) ] // disk command actions manifest [ DCheaderx=msb rshift (offset DC.headerAction+size DC.headerAction-1) DClabelx=msb rshift (offset DC.labelAction+size DC.labelAction-1) DCdatax=msb rshift (offset DC.dataAction+size DC.dataAction-1) ] manifest [ DCactionSeal=#321 DCaS=DCactionSeal*(msb rshift (offset DC.seal+size DC.seal-1)) ]