DLEWIS@SCU.BITNET (08/10/90)
Here's something I thought this discussion group might find of
interest:
There's another little known DOS extender (similar in purpose to QEMM,
386^MAX, and QRAM) called LASTBYTE. Like QRAM, it takes advantage of
those motherboards that use the Chips & Technologies chipsets to load
software into the memory between 640k and 1Meg.
Unlike all other such products, however, LASTBYTE has the unique
ability to use *ALL* 384k of that memory! Physical memory that sits
"behind" the display buffer, ROM's, etc., is not accessible with other
DOS extenders, but LASTBYTE uses a "bank-switching" technique to store
data there (e.g., for a ram disk, emulated EMS memory, etc.).
LASTBYTE does NOT use any protected mode software and so is fully
compatible with Windows 3.0. Moreover, since it does not rely on the
memory mapping capability of a 386, it does NOT remap any Extended
Memory into the 640k-1M region, nor does it even require a 386 - it
works on any PC that uses the C&T chipset and has at least 1M of
physical memory. LASTBYTE also requires DOS 3.0 or higher.
In addition to software to load device drivers and TSR's into high
memory, LASTBYTE includes software to mark (and later remove) TSR's,
device drivers that use high memory to implement a ram disk, to
emulate ems memory (both LIM 3.2 and 4.0), and to provide a
programmer's interface for allocating/deallocating high memory. The
latter can also be used with 4DOS (the shareware replacement for
COMMAND.COM) to move the 4DOS command processor and master environment
into high memory. And of course there's a program to display the
contents of high memory at any time.
There are command line options to select between normal and best-fit
memory allocation, and to delete environment blocks allocated for
TSR's.
Best of all, a fully functional but memory-limited version of LASTBYTE
is available free of charge for evaluation. If you like it, then only
$29.95 buys you an access key that can be used with the accompanying
LICENSE program to acquire unlimited access to all 384k. LASTBYTE can
be downloaded from a number of bulletin boards, including Vern's BBS
at (707) 778-8944, or directly from the manufacturer:
Key Software Products
440 Ninth Avenue
Menlo Park, Calif. 94025
(415) 364-9847
Enjoy!
Dan Lewis (owner, KSP)
Bitnet: DLEWIS@SCUACCliberato@drivax.UUCP (Jimmy Liberato) (08/13/90)
DLEWIS@SCU.BITNET (Dan Lewis) writes: >... >Unlike all other such products, however, LASTBYTE has the unique >ability to use *ALL* 384k of that memory! Physical memory that sits >"behind" the display buffer, ROM's, etc., is not accessible with other >DOS extenders, but LASTBYTE uses a "bank-switching" technique to store >data there (e.g., for a ram disk, emulated EMS memory, etc.). >... What on earth does "physical memory that sits 'behind' the display buffer..." mean? I understand how rom shadowing is done on 386 and NEAT 286 machines by remapping unused extended memory onto the bios adresses and how memory managers can find vacant addreses in upper memory to map extended memory into to allow hiloading of TSRs, drivers, and even the operating system kernal but you seem to be saying that, for example, I can have an EMS page frame at the same address as my video buffer through some sort of "bank-switching" (multiplexing?). Either I am completely misreading what you are saying or your method is indeed "little-known." Please elaborate! -- Jimmy Liberato liberato%drivax@uunet.uu.net {uunet|amdahl}!drivax!liberato
poffen@sj.ate.slb.com (Russ Poffenberger) (08/16/90)
In article <R2XNQK3@drivax.UUCP> liberato%drivax@uunet.uu.net (Jimmy Liberato) writes: >DLEWIS@SCU.BITNET (Dan Lewis) writes: > >>... >>Unlike all other such products, however, LASTBYTE has the unique >>ability to use *ALL* 384k of that memory! Physical memory that sits >>"behind" the display buffer, ROM's, etc., is not accessible with other >>DOS extenders, but LASTBYTE uses a "bank-switching" technique to store >>data there (e.g., for a ram disk, emulated EMS memory, etc.). >>... > >What on earth does "physical memory that sits 'behind' the display buffer..." >mean? I understand how rom shadowing is done on 386 and NEAT 286 machines by >remapping unused extended memory onto the bios adresses and how memory managers >can find vacant addreses in upper memory to map extended memory into to allow >hiloading of TSRs, drivers, and even the operating system kernal but you seem >to be saying that, for example, I can have an EMS page frame at the same address >as my video buffer through some sort of "bank-switching" (multiplexing?). >Either I am completely misreading what you are saying or your method is indeed >"little-known." Please elaborate! > Supposedly, in the C&T chipset, if you have more than 1Meg of memory, extended memory IS NOT remapped into the 640K to 1M memory space, rather conventional memory is really there, however disabled except for rom shadowing as supported by the chipset. Russ Poffenberger DOMAIN: poffen@sj.ate.slb.com Schlumberger Technologies UUCP: {uunet,decwrl,amdahl}!sjsca4!poffen 1601 Technology Drive CIS: 72401,276 San Jose, Ca. 95110 (408)437-5254