jimb@athertn.Atherton.COM (Jim Burke) (07/15/89)
I recently bought a PC with AMI bios that supports bios memory shadowing.
The system was sold as a 1 Mb system. When I boot, the machine goes
through a memory check of 1Mb. However, when I use Norton SI, it can
only find 640Kb of memory. I contacted the company I bought the system
from and they said the other 384Kb is used by the system for system stuff
like bios shadowing, etc. My question is this: is this a reasonable
explaination? Does bios shadowing actually capture main memory and make
it transparent to DOS? What other system features use main memory this
way? Seems to me that I didn't get a 1Mb machine, but rather a 640Kb
machine.
--
Jim Burke (408) 734-9822 (temp) | I'll stop posting when they pry my
jimb@Atherton.COM | cold, dead fingers from the smoking
{decwrl,sun,hpda,pyramid}!athertn!jimb | keyboard.mcdonald@uxe.cso.uiuc.edu (07/16/89)
>I recently bought a PC with AMI bios that supports bios memory shadowing. >The system was sold as a 1 Mb system. When I boot, the machine goes >through a memory check of 1Mb. However, when I use Norton SI, it can >only find 640Kb of memory. I contacted the company I bought the system >from and they said the other 384Kb is used by the system for system stuff >like bios shadowing, etc. My question is this: is this a reasonable >explaination? Does bios shadowing actually capture main memory and make >it transparent to DOS? What other system features use main memory this >way? Seems to me that I didn't get a 1Mb machine, but rather a 640Kb >machine. I got bit by the same syndrome, on a Dell 310. Yes, you really got only a 640K machine, and yes, they should not advertise them as 1 meg systems. Nor the 4meg-384K systems as 4 meg systems. If they advertise them as 4 meg systems, and I have a program that REQUIRES 4 whole megs (as I do), they are in trouble. Doug McDonald
joel@peora.ccur.com (Joel Upchurch) (07/17/89)
In article <6541@athertn.Atherton.COM>, jimb@athertn.Atherton.COM (Jim Burke) writes: > only find 640Kb of memory. I contacted the company I bought the system > from and they said the other 384Kb is used by the system for system stuff > like bios shadowing, etc. My question is this: is this a reasonable > explaination? Does bios shadowing actually capture main memory and make > it transparent to DOS? What other system features use main memory this > way? Seems to me that I didn't get a 1Mb machine, but rather a 640Kb > machine. My computer is a 16 MHz 286 using the NEAT chipset and the AMI BIOS. It will let the 384kb either be configured as extended memory or be used for ROM shadowing. It won't let it be configured as expanded memory though, which is what I have the other 3 megs configured as. -- Joel Upchurch/Concurrent Computer Corp/2486 Sand Lake Rd/Orlando, FL 32809 joel@peora.ccur.com {uiucuxc,hoptoad,petsd,ucf-cs}!peora!joel Telephone: (407) 850-1040 Fax: (407) 857-0713
jwi@lzfme.att.com (Jim Winer @ AT&T, Middletown, NJ) (07/18/89)
| |Somebody writes: | | | |I recently bought a PC with AMI bios that supports bios memory shadowing. | |The system was sold as a 1 Mb system. When I boot, the machine goes | |through a memory check of 1Mb. However, when I use Norton SI, it can | |only find 640Kb of memory. I contacted the company I bought the system | |from and they said the other 384Kb is used by the system for system stuff | |like bios shadowing, etc. My question is this: is this a reasonable | |explaination? Does bios shadowing actually capture main memory and make | |it transparent to DOS? What other system features use main memory this | |way? Seems to me that I didn't get a 1Mb machine, but rather a 640Kb | |machine. | | Doug McDonald writes: | | I got bit by the same syndrome, on a Dell 310. Yes, you really got | only a 640K machine, and yes, they should not advertise them | as 1 meg systems. Nor the 4meg-384K systems as 4 meg systems. | If they advertise them as 4 meg systems, and I have a program that | REQUIRES 4 whole megs (as I do), they are in trouble. On my DELL (220) you can shut off the shadowing of BIOS and use the other 384KB as extended memory. RTFM on your setup program and see if you can do it too. On the AMI bias, you're probably out of luck. Jim Winer ..!lzfme!jwi (Usually unable to reply to email outside AT&T) Those persons who advocate censorship offend my religion. Upuaut: a wolf-headed Egyptian deity | Voodoo: the art of sticking ideas assigned as Guidance System | into people and watching for the Barque of Ra. | them bleed. The opinions expressed here are not necessarily
mcdonald@uxe.cso.uiuc.edu (07/19/89)
>On my DELL (220) you can shut off the shadowing of BIOS and use the >other 384KB as extended memory. RTFM on your setup program and see >if you can do it too. The documentation is completely silent on this. There is no real FM on the setup program. But Dell tech support, which appears to be quite knowledgeable, says you can't. You CAN turn off the shawdow RAM, for sure - it is right there in the setup options list, and if you do it runs slower. But apparently you can't use the freed 384 K. At least nobody has told me how. Doug McDonald
jbh@trsvax.UUCP (07/19/89)
To Doug McDonald, I also have a Dell 310. I believe you can switch off ROM shadowing in setup. I am not sure what the problem is. I LOVE my 310, and would recommend it to anyone. Brad
jimb@athertn.Atherton.COM (Jim Burke) (07/20/89)
In article <1491@lzfme.att.com> jwi@lzfme.att.com (Jim Winer @ AT&T, Middletown, NJ) writes: >On my DELL (220) you can shut off the shadowing of BIOS and use the >other 384KB as extended memory. RTFM on your setup program and see >if you can do it too. >On the AMI bias, you're probably out of luck. Yep, I've verified that I am s**t out of luck with the AMI bios. Even if I disable shadowing, which I can, I still can't get back the 384k for extended memory or vdisk or whatever. It's just gone. But, I do have 1Mb of memory chips so technically, I have to admit it is a 1Mb machine. I was not thorough enough to ask whether I could actually USE 1Mb before I bought the machine - silly me, what a ridiculous assumption. (not that it's that big a deal) The dealer did offer to sell me a 1Mb upgrade at their cost which I have accepted. Live and learn... -- Jim Burke (408) 734-9822 (temp) | I'll stop posting when they pry my jimb@Atherton.COM | cold, dead fingers from the smoking {decwrl,sun,hpda,pyramid}!athertn!jimb | keyboard.
stenstro@algol.crd.ge.com (Ross Stenstrom) (07/21/89)
So, what IS shadowing anyway. Somebody must have come up with it for a
reason, you would think... ?
Ross Stenstrom
stenstro@algol.crd.ge.com (no m!) uunet!crdgw1.ge.com!stenstromWilliam.Cummins@bigtime.fidonet.org (William Cummins) (07/21/89)
Is the board a NEAT 286 by chance the board also has a AMI Bios and the
board will say the same thing with the shado ram enabled the board dose
have the memory in it ( providing it sayes that the shado ram is
inabled when you boot the machine after it ticks off the 640 ) the
memory can be releaced from the shado ram use on the neat board by the
setup 2 but it will slow it down if the memory is used for some thing
ie shado ram or disk chaching above 640 the norton si can't seem to
find it! William Cummins
--
William Cummins
Domain: William.Cummins@bigtime.fidonet.org
UUCP: ...!{tektronix, hplabs!hp-pcd}!orstcs!bigtime!William.Cummins
via Big Time Television (bigtime.fidonet.org, 1:152/201)jms@vpnet.UUCP (Jon Schattke) (07/22/89)
>From: stenstro@algol.crd.ge.com [Ross Stenstrom] >So, what IS shadowing anyway. Somebody must have come up with it for a >reason, you would think... ? Shadowing refers to the process of copying the ROMs into DRAM at boot-up. It effectively makes things from ROM run about 1.5-2 times faster (because it's very difficult to get EPROMs below about 200ns access, while DRAM at 80ns isn't _too_ expensive). Shadowing is especially important for 32bit systems (80386), because then the system can have only an 8-bit wide ROM (and cost less). Ain't ya glad you asked? --- Jonathan Mark Schattke There is _always_ one more bug. jms@vpnet.UUCP If u cn rd ths, u 2 cn bcum a prgrmr & mk bg $. VPNET is a free-to-users public-access system in a Chicago Suburb.
kiy@pte.UUCP (Kevin Young) (07/25/89)
In article <1288@crdgw1.crd.ge.com> stenstro@algol.crd.ge.com (Ross Stenstrom) writes: >So, what IS shadowing anyway... >Ross Stenstrom > stenstro@algol.crd.ge.com (no m!) uunet!crdgw1.ge.com!stenstrom Ross, Shadowing is a technique that increases the effective memory access speed of software sitting in ROM/EPROM by moving it to DRAM and then executing it there. EPROM technology is inherently slower than DRAM technology and typically requires 2 to 3 wait states per access depending on system clock speed whereas DRAM takes 0 to 1 wait states. The shadow RAM itself sits at the same memory location as the BIOS EPROM/ROM and is switched by hardware on the CPU card. The initialization procedure is to first copy the contents of the EPROM to low memory, switch the select bit to enable the shadow DRAM, and then move the copy in low memory back into the shadow DRAM. Finally, the write-enable to the shadow DRAM is disabled, preventing errant programs from erasing its contents. Shadowing is relatively easy to implement in a PC when using 1MB memory chips because the memory needed for shadowing is already available. It is simply hidden behind the BIOS chips by the address decoder. Hope this helps! Kevin -- >|< Kevin I Young uunet!edsews!pte!kiy Precise Technology & Electronics, Inc. Custom Automated Test and Measurement Equipment for Industry Old Saying: "If you can't do it in real time, then don't do it at all" - me