Path: utzoo!attcan!uunet!clyde.concordia.ca!news-server.csri.toronto.edu!mailrus!iuvax!silver!herrj From: herrj@silver.ucs.indiana.edu (Jonathan R. Herr) Newsgroups: comp.sys.ibm.pc Subject: XT...Beyond 640K...How do I get there? (Summary)(LONG!) Message-ID: <38962@iuvax.cs.indiana.edu> Date: 19 Mar 90 21:04:11 GMT Sender: root@iuvax.cs.indiana.edu Reply-To: herrj@silver.ucs.indiana.edu (Jonathan R. Herr) Organization: Nonewhatsoever. Lines: 228 Last week I posted a few questions about memory beyond 640K on an XT-compatible system. Below are the responses that I received as well as a few addtitional comments by me. Thanks to all who responded! It has been most educational. THIS IS VERY LONG! Unless you are really interested, go to the next article now! ---------------------------response #1------------------------------------- From: bbesler@vela.acs.oakland.edu (Brent Besler) Message-ID: <357@vela.acs.oakland.edu> Date: 14 Mar 90 20:16:31 GMT Organization: Oakland University, Rochester MI |Things vary from board to board, but generally memory between 640K and 1024K |can't be used by DOS programs. If you want to use EMS memory on an XT there |are a number of boards that emulate it, but it is real slow on an XT. | | Brent H. Besler Your right. I was reading the book wrong(or just in a hurry!). Here is the definition given on page 7 of the user's guide for Microsoft's MS-DOS. Expanded memory is memory beyond 640 kilobytes that uses page-switching technology and that can be used in most personal computers. If you install the expanded memory-board hardware and a special program called the expanded memory manager, then -> applications that can use expanded memory gain access to this -> additional memory... _______________________________response #2____________________________________ Date: Wed, 14 Mar 90 23:24:01 EST From: gatech!mit-eddie!genrad.com!jpn (John P. Nelson) Message-Id: <9003150424.AA04295@spot.genrad.com> Organization: GenRad, Inc., Concord, Mass. ||>I have a question about the DOS 4.01 use of memory(RAM). | |Actually, your question has nothing to do with DOS 4.01: it is a PC |architecture question. | |>I have 1024K of memory on my XT mother board | |This is quite unusual, and I have no direct knowledge of your specific |hardware, so I am guessing to some degree. | |The reason this is unusual is because an XT has a total address space |of 1024K: The upper 384K of the address space is reserved for video, |ROMS and other memory mapped devices. Therefore, only 640K of your |system's ram can be addressed directly. Your system MUST have some |nonstandard hardware for accessing the additional memory. Actually, it is unusual because it didn't come installed. I put the chips from another mother board in mine. Both came with 512K. The DIP switch settings allow for up to 1024K. Obviously, though, this is irrelevant. | |>but DOS refuses to recognize it. | |Of course it does. Any version of DOS is only aware of the 1Meg |address space. 384K of your ram is hidden in some way by nonstandard |hardware. This is still somewhat unclear to me. I don't believe there is any non-standard hardware. But, I'm the one who wouldn't know. I'm not familiar with the IBM family(yet!). Is there any particular reason that you think there is non-standard hardware? Is it because the BIOS ROM sees it? | |>I realize that anything above 640K is expanded memory. | |How do you know this? See the definition in response #1. | |If true, expanded memory is a bank-switch scheme. 64K of the "reserved" |address space is used for 4 16K "banks", into which any of the available |expanded memory pages may be mapped. That's pretty much what the definition says, I believe. | |EMS (expanded memory system) is a SOFTWARE standard: The hardware that |implements it varies widely, and in fact, the address range into which |the EMS banks are mapped is not fixed. You need to load an EMS |"driver" program (it should have come on your MSDOS distribution disk) |which will allow programs that know how to USE EMS to access this |memory: without the driver program, the expanded memory is |inaccessable and useless. Right again! I guess I'll take the extra memory out and put it back in the old board. My brother-in-law is wanting to get himself a computer. I guess I'll give that one. | |> What do I have to do to get DOS to recognize the other 384K? | |I don't think there IS any way. DOS only knows about conventional |memory in the first 640K | |Oh, I'll modify that. DOS 4.0 can load it's "buffers" into expanded |memory if you have loaded an EMS drivers. In my opinion, this capability |is not really very useful. Agreed. | |> and, What will it be used for? | |If you have loaded an EMS driver, there are many programs that can use |the EMS storage as sort of a fast disk. There are ramdisk programs, |cache programs, and other applications that can use EMS memory directly |(Turbo C's integrated environment can use up to 64K of expanded memory, |and Lotus 1-2-3 can use all the available expanded memory for large |spreadsheets). | |You must realize that most applications will not be able to use the |EMS memory at all: Only programs that know how to talk to the EMS driver |can use the expanded memory. | |>I've been reading the User's Guide and Reference Guide and the book says |>that I need an EMS controller. Is this right? | |Almost. Your motherboard probably has hardware that implements EMS using |the extra 384K of ram. What you need is a program: the EMS DRIVER! Well, I get the suspicion that perhaps the the hardware is there. Is there anything specifically I can look for to confirm this? There is no card. Maybe it's on-board. Would the BIOS take care of this. I'm not exactly sure what the BIOS ROM does. Would it be "shadowing" the rest of memory? | |>I mean, the memory is |>on-board and the BIOS ROM seems to recognize it on boot-up. Why would |>it need a controller for something on-board? | |Because EMS memory does not fit into the normal address space. Without |using an EMS driver, there is no way to access this extra memory. | |>I've tried to install the |>SMARTDRV.SYS but get the error "No Expanded Memory Manager." | |This is referring to the EMS driver. If no driver is loaded, SMARTDRV.SYS |has no way to access the Expanded memory. | | |Feel free to repost or summarize my response to comp.sys.ibm.pc. Thanks. I did. |-- | john nelson | |UUCP: {decvax,mit-eddie}!genrad!jpn |smail: jpn@genrad.com --------------------------------response #3----------------------------------- Message-Id: <9003151208.AA25515@ucsd.edu> Date: Wed, 14 Mar 90 20:38:25 PST From: ames!ucsd!pnet07.cts.com!johnlee (John Wiley) |You've probably already received many replies as to the technical nature of |your problem. I'd like to add my experience with one solution. I have an XT |clone as well, and bought an AST RAMpage card. It came with 512k of RAM, |Desqview, a print spooler program, and a Ramdisk driver. I tried using it for |multitasking under Desqview and found that it does work as advertised. I can |run several programs, and switch between them, and even copy data between |them. But I find that I don't use it. The trouble is, it makes the computer |too slow. All I use my $400 investment for is a Ramdisk that doesn't use up |any of my 640k. For the money, I suggest you consider a cheap 386SX. I |tested one and found it took 4 seconds to draw a simple CAD image that takes |my XT 23 seconds. Well worth $1200, in my opinion. | |UUCP: nosc!pnet07!johnlee (John Wiley - San Diego, CA.) |ARPA: simasd!pnet07!johnlee@nosc.mil |INET: johnlee@pnet07.cts.com Thank you! I'm looking into getting a 386 later in the year. I'm hoping that the 486 might bring down the already-low price of the 386 to my range. -------------------------------response #4---------------------------------- Date: Tue, 13 Mar 90 14:58:47 pst From: "Michael D. Kersenbrock" Message-Id: <9003132258.AA20688@copper.WR.TEK.COM> To: herrj@SILVER.UCS.INDIANA.EDU Organization: Tektronix, Inc., Beaverton, OR. |Puting 1Meg on a AT backplane may get the 384K "back" by having it show |up as extended memory (above 1 Megabyte). In a XT, you are probably S.O.L., |there's no extended memory to be had. "High memory", between 640K and 1Meg |are filled with things like your display memory, Bios ROMS, and such. | |Although pieces theoretically could be mapped into free spots here and |there within "high memory", your backplane probably doesn't do it. That |384K is probably gone on a XT. If you have a hercules monochrome or a CGA |type display, you *could* add 64K or 96K (respectively) to your conventional |memory using EMS 4.0 (with EEMS type hardware). If you are using EGA |or higher modes of video, you couldn't add any more conventional memory |space anyway. Well, I'm using a hercules monochrome. But, it sounds like more of a hassle than it's worth. | |Check the forsale group later in the week for my posting. I have a |couple AST boards (RAMPAGE/2 and a SIXPAKPREMIUM) for sale that have EEMS |type hardware in their LIM EMS 4.0 implementation (they use the REMM.SYS |expanded memory manager). I used to use them with my 10Mhz XT (which is |now a 12 Mhz AT). | |Mike Kersenbrock |Tektronix Microprocessor Development Products |michaelk@copper.WR.TEK.COM |Aloha, Oregon ------------------------------------------------------------------------------- --------------------------------end of responses------------------------------- ------------------------------------------------------------------------------- Again, thanks to everyone. I hope that others may have benefitted as have I. Jonathan R. Herr|---|herrj@silver.ucs.indiana.edu|---|Standard Disclaimer|