gjs@inmet.inmet.com (04/07/90)
> We reccently got an IBM PS/2 486 machine and I have been > switched back to programming on the IBM after a lapse of 2 years. Can > anyone please tell me if the DOS 640 K limit has been abolished? We > have DOS 4.01 and from what I have read so far, that limit is still > there. The February and March issues of BYTE have several articles on getting past the 640K limit. For running applications, the major kinds of tools are: Expanded memory (special boards, with LIM drivers), which can be used as data space by many programs such as 123, Paradox 3, Framework III, ... Programs such as QEMM and 386-Max, which can make extended memory (above 1 Meg) look like expanded memory, and can load some device drivers, TSRs, and (in some cases) DOS FILES and BUFFERS into holes between 640K and 1M, leaving more application space. Application switchers, such as Headroom and Software Carousel, which allow you to swap applications out to expanded memory, extended memory, or disk, and later restore their state with a "hot key." Multitasking DOS systems, such as DESQview, which allow applications to run concurrently, each with a "virtual" 500K or so. I don't know whether DESQview must directly support an application to run it concurrently, or whether there are "classes" of programs it can or cannot handle. Disk caching programs (See February PC World) and RAM disks which use expanded or extended memory. These don't save space directly, but can significantly speed up database operations, compiling and linking, frequently invoked batch files, etc. With some programs that have code in an overlay file (notably Framework), you can minimize the size of the overlay buffer to effectively keep the overlay code in high memory. -- George Snyder uunet!inmet!gjs (from usenet) -- Intermetrics, Inc. gjs@inmet.inmet.com (from internet/MILnet)
akcs.reed@tronsbox.UUCP (reed) (04/12/90)
Hmm, well no-ones abolished the direct 640 Kb limit under MS-DOS, yet. The extenders ARE quite expensive, from $2400 on up if I remember correctly. And the only languages supported (by Microsoft) for OS/2 are C and assembler. Unless someone knows better than me, sounds like you're out of luck in those areas. However, all is NOT lost. There are several utility libraries that provide run-time linking, sophisticated overlay management, or virtual memory. These packages are generally linked into your program, and will usually require special instructions in your program to control them. I've never used any of these, either. Continuing on with something I've never used myself, how about Unix? Sounds like you've got the equipment to run it with, and of course it has a larger program address space as well as OS support for virtual memory. I've been told that the Microsoft compilers for Unix and DOS are source compatible. I'd be interested in hearing what you decide and how it works out. Regards, REED from HighWater Mark BBS (201-985-5486, 2400/8/n/1)
2011_552@uwovax.uwo.ca (04/12/90)
In article <2624014d:139.1comp.sys.ibm.pc;1@tronsbox.UUCP>, akcs.reed@tronsbox.UUCP (reed) writes: > Hmm, well no-ones abolished the direct 640 Kb limit under MS-DOS, yet. The > extenders ARE quite expensive, from $2400 on up if I remember correctly. And ????? > the only languages supported (by Microsoft) for OS/2 are C and assembler. > Unless someone knows better than me, sounds like you're out of luck in those > areas. Prices in US dollars (as of the April 1990 issue of _Personal_Workstations_): Phar Lap Tools (Dos-extender for 386): $495 MicroWay (Fortran, C, Pascal) : $595 each (386 dos extender versions) At least 5 other dos-extended 386 fortrans are available; at least 3 other dos-extended 386 c compilers are available. (I believe the Microway compilers are at the low-price end; as always, check to be sure that the compiler will be able to handle your tasks.) Phar Lap also makes a virtual memory extension (VMM) for their dos-extender (additional $295); VMM versions of the Microway languages are $100 extra (each). -- Terry Gaetz -- gaetz@uwovax.uwo.ca -- gaetz@uwovax.bitnet
georgf@polari.UUCP (George Forsman) (04/14/90)
In article <2624014d:139.1comp.sys.ibm.pc;1@tronsbox.UUCP> akcs.reed@tronsbox.UUCP (reed) writes: >Hmm, well no-ones abolished the direct 640 Kb limit under MS-DOS, yet. The >extenders ARE quite expensive, from $2400 on up if I remember correctly. And >the only languages supported (by Microsoft) for OS/2 are C and assembler. and Pascal, and FORTRAN, and BASIC. C is the language of choice, and thus examples are given in C. However, the other languages are supported as well. -George ...!uunet!uw-beaver!sumax!polari!georgf