SOTE - Introduction

State of the Emulator: Known Unknowns

The following is a list of the outstanding unanswered questions about the the emulators correctness with respect to the original hardware. These questions arise from incomplete, incorrect or contradictory documentation.

  • Is ITP/ITS the end of the indirect chain?
  • formatDecimal(),formatDecimalDIV(): What happens if we try to write a negative number to an unsigned field?
  • formatDecimal()formatDecimalDIV(): Adjusted length is too small; what do we fill in?
  • getMFReg18(): Correct handling of DU.
  • EISWriteIdx()/EISWiriteCache(): Write cycle on every bit.
  • mvne(): Temp hack to get MOP to work.
  • btd(): "illegal eis modifier"
  • doFault: Proper state of CU and FR for double fault.
  • interruptL66(): Negative ACK of unimplemented function.
  • doFNPFault unimplmented.
  • Read(): went appending in BAR mode?
  • executeInstruction(): Correct subFault value for attempted execution of privileged instruction.
  • executeInstruction(): Correct subFault value for instruction not allowed in XED/XEC.
  • executeInstruction(): Correct subFault value for instruction not allowed in RPT.
  • executeInstruction(): Missing check for RPL.
  • executeInstruction(): Is stiTally implemented correctly.
  • Should integer division be rounded towards 0 or -infinity.
  • RTCD: does SDW-R1 refer to the SDW of the target segment? (ticket #16)
  • buildAUXPTWaddress() are bits 16 and 17 OR'd or added?
  • send_general_interrupt(): Should the SCU unit number be calculated from the Port Configuration Address Assignment switches or the CPU configuration switches?
  • ABSA.
  • RPL
  • T&D absolute mode bit.
  • Under what conditions should doFault set cu.rfi?
  • Verify that RTCD ACV is handled correctly.
  • Verify the MIF set logic.


  • History registers.
  • RPL instruction.

The following are questions about the behavior of the emulator's operation independent of the actual H/W.

  • If the emulator detects an internal failure, should it crash, or attempt to signal Multics that there is a 'hardware' issue?


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