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Conference 49.910::kav30

Title:VAX on VMEbus: KAV30
Notice:Could have been as fast as 68K but its a VAX!
Moderator:CSSVMS::KAV30_SUPP
Created:Thu Apr 18 1991
Last Modified:Fri Aug 02 1996
Last Successful Update:Fri Jun 06 1997
Number of topics:159
Total number of notes:645

67.0. "ROM/EPROM questions" by MLN08::CASTELLUCCI (EIS - Italy /DTN: *793-2292) Thu Sep 24 1992 16:54

	Questions coming from a TOEM utilizing Motorola hw

	1) The KAV30 can have 2 EPROMs of 16 bit:
	   is the access to them made in one or two cicles?

	2) Is KAV30 able to handle the code of the application
	   using directly the EPROM/ROM without loading the
	   code into its DRAM or is there any VAXELN constraint?

	Thanks/Aldo
T.RTitleUserPersonal
Name		DateLines
67.1GOBANG::LEMMERThu Sep 24 1992 17:3029
Hi,

	here are the answers:

	
	1) The KAV30 can have 2 EPROMs of 16 bit:
	   is the access to them made in one or two cicles?

	>> the rtVAX goes to the EPROM in one cycle


	2) Is KAV30 able to handle the code of the application
	   using directly the EPROM/ROM without loading the
	   code into its DRAM or is there any VAXELN constraint?

	>> in general the rtVAX has two possibilities:

	boot prb0 -> run the application from ROM

	boot prb1 -> copy to RAM, then run it.

	>> since the EPROM is far slower than RAM, it's not a good
	>> idea to run an application out of the EPROM. As far as I know
	>> there are additional constraints, therefore on the KAV30 you
	>> only have option two: copy to RAM and run it from there.

Regards,

	Thomas
67.2maybe 2 cycles ?PDV01::ANDREACETue Mar 02 1993 17:0410
    Hi Aldo, 
    it seems to me (experience with 68K cpus) that you can't get 32 bit in
    1 cycle when the peripheral component is giving you 16 bit at  a cycle.
    More probably the CVAX will use 2 cycles to get the same amount of info
    it can get from DRAM chips (wait state apart).
    
    
    	Regards.
    
    		Raffaele.
67.3HERR::CROSBIEWed Mar 03 1993 08:5012
    Re: .2
    
    The rtVAX 300 firmware accesses the KAV30 user roms using a single
    longword cycle.
    
    Re: .1 
    
    The B PRB1 option is the only option supported for loading the KAV30
    from the on-board ROMS (the KAV30 specific cpu data is at a fixed
    offset in the kernel and is not easily re-locatable).
    
    Graham