Talk:LOADALL: Difference between revisions

Content deleted Content added

Inline

Revision as of 22:26, 27 March 2012

Please add {{WikiProject banner shell}} to this page and add the quality rating to that template instead of this project banner. See WP:PIQA for details.

Computing Start‑class Low‑importance

	This article is within the scope of WikiProject Computing, a collaborative effort to improve the coverage of computers, computing, and information technology on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.ComputingWikipedia:WikiProject ComputingTemplate:WikiProject ComputingComputing articles
Start	This article has been rated as Start-class on Wikipedia's content assessment scale.
Low	This article has been rated as Low-importance on the project's importance scale.
	This article is supported by Computer hardware task force (assessed as Low-importance).

The article does not shed light on the reasons for the presence and "undocumented" status of the LOADAL in the first place. I believe it along with (still undocumented AFAIK)pins on the 80286 has to do with supporting Intel's "in circuit emulator". In the same vein is the "undcumented undocumented" instruction code 0F 04 (on 286) which in my wildest guess is some kind of RESTORALL... or return from in circuit debugging instruction; but when executed on a normal 80286, this blocks (not even an NMI gets out, only a processor RESET does) because, in my guess again, it must be waiting for a transaction on an alternate BUS (alternate pins) which of course is unimplemented on the platform and possibly also on the CPU if it is a regular 286.

Could someone who had access to in circuit emulators provide information ?

Ninho

0F 04 opcode problem

I am interested in 0F04 problem too. I've recently updated this list with information on the 0F04 opcode which I had retrieved from Sandpile.org. It says the 0F04 opcode should be a halting sequence - at least, it was emulated on some BIOS, doing OUT to diagnostic port followed by halt. But you may be right with your guess - hope this information will help. Too bad all these undocumented and still unexplored things fade away...

intelfx

77.41.56.81 (talk) 21:34, 27 December 2010 (UTC)[reply]

I can confirm that the OF 04 opcode also halts the CPU on 386, at least Am386DX-40. I used DebugX, remapped the default INT06 handler to an INT3 breakpoint trap, but this instruction is never reached when OF 04 is executed. It should be possible to revive some old sources on ftp.gwdg.de/pub/misc/x86.org/source and eventually try it with 0F 04 and see what happens ;)

DiederikH DiederikH (talk) 22:26, 27 March 2012 (UTC)[reply]