23031_676@uwovax.uwo.ca (01/13/90)
The technical report is fine for hackers, but please try to answer this more
elementary question: Like many others, I have purchased a 1 mb system (NEC
286), yet it is not clear that the extra 360 can be used for anything. Modal
response is yes/no(!) DesQ and other software manuals speak about use of
extended memory over 1 mb, but not between 640 and 1 mb. Is there any way,
for any kinds of software, of getting any use out of this memory?
.
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Ben Singer Department of Sociology
University of Western Ontario
Singer@uwo.ca London, Ontario
Singer@uwovax.bitnet N6A 5C2
(519) 660-0671 (home)
(519) 679-2111 Ext 5137davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr) (01/15/90)
In article <4668.25aed7f2@uwovax.uwo.ca> 23031_676@uwovax.uwo.ca writes: | The technical report is fine for hackers, but please try to answer this more | elementary question: Like many others, I have purchased a 1 mb system (NEC | 286), yet it is not clear that the extra 360 can be used for anything. The answer is, on *most* systems the extra 384k shopws up as extended memory above 1MB. This can be used as RAMdisk. On some systems the BIOS takes part of it to keep copies of the BIOS, etc, in fast memory. I suggest you look at your screen when booting and see how much memory is reported by POST. That's what you have. There are also some programs around which will allow using the extended memory for print spooling. Unless you do some modestly tricky things you can't use the memory from 640k-1MB for regular systems memory, and most 286 systems don't map the extra memory there, anyway. -- bill davidsen (davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen) "Stupidity, like virtue, is its own reward" -me
johne@hpvcfs1.HP.COM (John Eaton) (01/24/90)
<<<< $How would things have worked out if IBM had put this 384k block at the bottom $of the memory (0-384). That would have left no constrictions on upward $expansion except the 8088. And that problem would have been remedied by $the 80286. -ted- ---------- You still need 1K of RAM at 0000:0000 for the Interrupt vector table. They might have had an easier time expanding if they had allowed for other processors with differing sizes of segments. Instead of fixing it at 4 bits you could have gone to 5,6,7 etc. In order to understand some of the limitations of the PC you must remember how the 8086 came to be. Intel was on a roll with the 4004/8008/8080 and decided to go all out and design a micro that really had some POWER. It was to be something that could challenge the minis and become the chip of the 80's. I believe it was originally called the "432". But they still needed to keep business coming in the door until this wonder chip was ready so they decided to do a quick and dirty enhancement of the 8080. This was the 8086. It's only purpose was to keep the 8080 family alive until Intel could deliver its real processor. Its hard to fault the designers for any design decisions that were appropriate for it's expected lifespan. John Eaton !hpvcfs1!johne
mcdonald@aries.scs.uiuc.edu (Doug McDonald) (01/25/90)
In article <21990004@hpvcfs1.HP.COM> johne@hpvcfs1.HP.COM (John Eaton) writes: >In order to understand some of the limitations of the PC you must remember >how the 8086 came to be. Intel was on a roll with the 4004/8008/8080 and >decided to go all out and design a micro that really had some POWER. It >was to be something that could challenge the minis and become the chip >of the 80's. I believe it was originally called the "432". But they still >needed to keep business coming in the door until this wonder chip was ready >so they decided to do a quick and dirty enhancement of the 8080. This was the >8086. It's only purpose was to keep the 8080 family alive until Intel could >deliver its real processor. Its hard to fault the designers for any design >decisions that were appropriate for it's expected lifespan. > Yes, but why did they have to botch it? One tiny, simple change in it, that would not increase (it probably would DECREASE) the gate count, and it would have been MUCH better: make the segment registers a simple extension of the address - that is, the 8086 would have used only 4 bits of the segment registers, but the 80286 would use 8 and the 80386 all 16. A second change to the 8086, that would have added two instructions, would have been to add "add carry to segment register" and "subtract carry from segment register" instructions. IT would still get flamed for segments, but at least the 80286 would have been able to run 8086 code directly. Doug McDonald