Subject: FPP-8/A Floating Point Processor

From: [email-masked] (Bill Haygood)
Date: 16 Jan 1994 18:02:26 GMT

If you can answer any of the following questions about the FPP-8/A,
I would appreciate a response.  Please cite a printed reference, if
possible (but, please respond anyway if not!):

	Questions:
	(1) Once the FADDM/FMULM bit gets set, does it stay set until
 		the next FPICL or does it get cleared with each new FPP
		instruction execution ?  (Presently implemented as the
		latter in my emulator.)
	(2) What do opcodes 5100-5177 do ?  (Presently implemented as
		Unknown OpCodes causing an exit from the emulator.)
	(3) What do opcodes 6000-6177 and 7000-7177 do ?  I think they
		they refer to the mnemonics IMUL, IMULI, LEA and LEAI.
		What format do they use and what should an instance of
		execution produce ?  (Presently implemented in my
		emulator as my GUESS--and when I guess, I frequently
		get it wrong!)
	(4) The OS/8 Handbook, page 5-9 states that TRAP3 acts as a
		JMP to PDP8 mode and that TRAP4 acts as a JMS to PDP8
		mode.  Any ideas what this means ?

--Bill Haygood