[Simh] [Simh-dev] pdp11/70: trap to 4 or 10

[Walter F.J. Mueller]

Hi all,

Bob Supnik answered directly to me on this. Citing the J11 microcode, the
definitive statement is: JMP,JSR for mode 0 traps to 10 on a J11, and by
extension also on a 11/70 (J11 was feature compatible with the 11/70),
as it is emulated in simh.

That answers my question. Nevertheless it might be amusing to summarize
what DEC manuals state:

  1. The 11/45 Processor Handbook (1971) p 234 {private collection}
     "Illegal and reserved instructions,... JSR R, JMP R, trap to 10"

  2. The PDP-11 Processor Handbook for  04/34a/44/60/70 (1979) p 131 {bitsavers}
     "Illegal instructions (JSR,JMP for mode 0) trap to 4"

  3. DCJJ11 Microprocessor User Guide - Preliminary (1983) p C-7 {bitsavers}
     Preliminary PDP-11/84 Technical Reference Manual (1985) p B-10 {bitsavers}
     PDP-11/94-E System User and Maintenance Manual (1990) Tab D-2 {bitsavers}
     "JMP %R or JMP %R trap to 4 on 44,45,70,J11, and trap to 10 on others"

Amazing is that the first manual from 1971 gets it right, but none of the
later ones I looked into.

	   With best regards,

		     Walter
-- 
Walter F.J. Müller    Mail:  W.F.J.Mueller at gsi.de
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