Shareware Overload/ShartewareOverload.cdr/progm/assemutl.zip/MEMDRV.ASM

Assembly Source File | 1985-05-11 | 10KB | 356 lines

title    ramdvr 01-01-84        [01-01-84]
;-------------------------------------------------------------------------------
; RAMDVR.SYS -- Modification to Dan O'Brien's excellent program by
;        Tom Perry, CIS 70455,751 or FORUM ][ 305/772-4444.
;
;        This modified version performs the same function described
;        below.    The only difference is that it runs as a "device
;        driver" on DOS 2.0 and up.  This means not only that it gets
;        control earlier and thus works faster, but also that it will
;        not cripple the system if you want to install a device that
;        takes a fair amount of memory.    For instance, I had a virtual
;        disk driver that uses 180K.  With switches set for 64K, it
;        could not be installed.  To get around this with MORRAM.COM,
;        you have to put logic in AUTOEXEC.BAT to switch between two
;        CONFIG.SYS files; it can be done (I did it for a while), but
;        it's messy and takes more disk space -- a LOT more if you're
;        working with a hard file with its large allocation unit.
;
;        To use this version, simply create a file on your boot disk
;        named CONFIG.SYS containing the line DEVICE=RAMDVR.SYS
;        and copy RAMDVR.SYS onto the boot disk.  If you already have
;        a CONFIG file, enter DEVICE=RAMDVR.SYS as its first line.
;        Set your switches for 64K, turn on the machine, and notice
;        the difference.  To learn how it works, read Dan's description
;        below.
;
;        There IS a penalty for doing it this way: Part of the program
;        remains permanently installed in the system as a device driver,
;        eating up a few bytes of precious RAM.    I have left enough to
;        keep the system from crashing if the device driver is driven
;        again (for instance, by a MODE RAMCHECK command).  More bytes
;        could be saved if you're willing to take that slight risk;
;        probably the minimum you'd need to keep is the four bytes
;        constituting the device driver chain at label "next_dev";
;        uncomment the indicated line if you want to try this.


; MORERAM.COM - by Daniel M. O'Brien (v 1.0) 21 Dec 1983
;
;          - freely adapted from a PC-WORLD User-to-User column program
;        of the same name (object disassembled using ASMGEN) and from
;        a program shown in a DR. DOBBS Journal article
;        (16 bit Toolkit) called MEMSIZE.
;
; This program has two (or three) purposes.
;
;    1) Allow a PC to use more memory than is allowed via the motherboard
;    memory switches (544 K bytes for the 64K motherboard and 640 K bytes
;    for the newer 256K motherboard). And because of 1)...
;
;    2) Allow faster power-up sequence by setting the motherboard memory
;    switch settings to 64 K bytes installed.
;
;    And as long as we are in the neighborhood...
;
;    3) Patch the ROM BIOS data area to indicate that this PC has four
;    floppy diskettes installed (instead of the normal two). This is for
;    ram disk emulation programs that require the motherboard equipment
;    options switch to be set to include the number of ram disks.
;    This is most notably required by the AST RESEARCH ramdisk program
;    called SUPERDRV. This code is commented out. To use it you must
;    uncomment out the code and reassemble. Search for the string:
;
;            ;stub***
;
; Using MORERAM.
;
;    First, copy MORERAM.COM to your boot device (floppy or fixed).
;    Next, create or edit your AUTOEXEC.BAT file found on your
;    boot device to include MORERAM as the **FIRST** program that
;    will be executed. This is important as results are not guaranteed
;    if MORERAM is not the first command executed at boot time.
;    Next, open the covers of your PC and set the memory switches
;    to indicate that your PC only has 64K.
;
;    Now try rebooting your PC using the Alt-Ctrl-Del sequence.
;
;    MORERAM will first display a hello banner and the amount of
;    memory DOS thinks your PC has (should be 64K). Next, MORERAM
;    will pause a second or two while it determines how much memory
;    your PC really has. (It also clears this memory in the process
;    to eliminate PARITY 2 errors later).
;    Once the physical memory limit is determined, MORERAM will display
;    that amount and then automatically re-boot. (Don't get excited,
;    this won't loop indefinitely, because...) The next time MORERAM
;    is again executed from your AUTOEXEC.BAT it will find that the amount
;    of memory DOS thinks you have will be the same as that installed, and
;    a reboot will be avoided!
;
; I use this program on my PC that has 576K (64K + 512K) worth of memory.
; Also, I have successfully tested it with 704K (64K + 512K + 128K) of memory,
; but this requires placing memory into the semi-forbidden zone (segment A000)
; designated by IBM as "reserved". But that's ok, as long as you don't install
; memory beyond this into the B000 segment where monochrome and graphics display
; memory live!
;
; Questions or comments should be left for me (DAN OBRIEN) on Gene Plantz'
; BBS in Chicago, IL (312-882-4227). I will attempt to fix bugs that may
; crop up, but I make no guarantees. You use this at your own risk (just like
; I do!). If you break something valuable, it's your own fault.
;
;-------------------------------------------------------------------------------


lf    equ    0ah
cr    equ    0dh
;
;initial values :    cs:ip    0000:0100
;            ss:sp    0000:ffff

s0000    segment
    assume ds:s0000, ss:s0000 ,cs:s0000 ,es:s0000
    org    $+0000h
;
;    device driver header and logic added 1-1-84 by Tom Perry.
;
next_dev    dd    -1
        dw    8000h           ;char device
strategy    dw    dstrategy
interrupt    dw    dinterrupt
whatcall    db    'RAMCHECK'      ;name

dstrategy    proc    far

    mov    cs:rh_seg,es
    mov    cs:rh_off,bx        ;save ptr to request header
    ret

dstrategy    endp

rh_off    dw    0
rh_seg    dw    0

dinterrupt    proc    far

    cld
    push    ds
    push    es
    push    ax
    push    bx
    push    cx
    push    dx
    push    di
    push    si

    mov    al,switch
    cmp    al,0ffh
    je    continue
    mov    al,0ffh
    mov    switch,al

    call    memdrvr

    mov    bx,rh_off
    mov    ax,rh_seg
    mov    es,ax        ;pt to req hdr
    mov    ds,ax
    mov    ax,offset last_place
;*risk    mov    ax,offset strategy ;USE THIS LINE TO SAVE RAM AT SOME RISK!
    mov    14[bx],ax    ;set ending address
    mov    ax,cs
    mov    16[bx],ax    ; including segment
continue:
    mov    ax,0100h
    or    3[bx],ax    ;set device status as DONE with NO ERROR

    pop    si
    pop    di
    pop    dx
    pop    cx
    pop    bx
    pop    ax
    pop    es
    pop    ds

    ret

switch    db    0,0,0        ;one time switch & bug protection
last_place db    'LAST PLACE'

dinterrupt    endp


memdrvr proc    near

;    end of device driver modifications by Tom Perry
;    (except as noted below).

start:    jmp    begin

hello    db    "Device driver to use MORE RAM than switches (v 1.1) ",cr,lf
    db    "by Daniel M. O'Brien and Tom Perry (1 Jan 1984)",cr,lf,lf,'$'
inmem    db    " Current memory is $"
kbytes    db    " K bytes. $"
findmem db    cr,lf," Physical memory is $"
analyze db    " Analyzing & Clearing...$"
reboot    db    " Re-Booting...",cr,lf,'$'
done    db    cr,lf," Memory size is set correctly.",cr,lf,'$'

begin:
    mov    dx,offset hello     ; say hello
    mov    ah,9
    int    21h

    mov    dx,offset inmem     ; how much memory?
    mov    ah,9
    int    21h

; next 3 lines of code added 1-1-84 by Tom Perry for device driver environment.

    int    12h        ; ask bios how much memory
    mov    cl,6
    shl    ax,cl        ;shift left 6 times to look like PSP+2

;    mov    ax,ds:2     ; get top segment number from program prefix

    push    ds        ; save ds for later

    push    ax        ; save top segment number for later
    mov    cl,6        ; convert to K bytes
    shr    ax,cl
    call    decout        ; and display

    mov    dx,offset kbytes    ; display "K bytes"
    mov    ah,9
    int    21h

    mov    dx,offset analyze    ; display analyzing message
    mov    ah,9
    int    21h

    xor    ax,ax        ; stop parity errors while we poke around
    out    0a0h,al

    pop    ax        ; recover top segment number

loop:    mov    bx,0        ; look into this 16 byte "segment"
;    cmp    ax,0a000h    ; is ax = beginning of "reserved" addrs?
                ; stop at display memory instead!
    cmp    ax,0b000h    ; is ax = beginning of "reserved" addrs?
    je    ramend        ; yes, so end of ram
    mov    ds,ax        ; no, so use this as segment
    mov    [bx],ax     ; write contents of ax to ds:bx...
    mov    cx,[bx]     ;... and read it back to cx
    cmp    ax,cx        ; does data read = data written?
    jne    ramend        ; if it not, then ran out of ram!

    mov    cx,8        ;    else - reset this 16 byte area
    mov    es,ax
    xor    ax,ax        ;      reset means 0000h
    xor    di,di
    rep    stosw        ;    to prevent parity errors when used

    mov    ax,ds        ; copy ds to ax...
    inc    ax        ;... increment it...
    jmp    loop        ;... and loop

ramend:
    mov    bx,ax        ; found real end of ram - save it

    mov    al,80h        ; enable parity errors for the future
    out    0a0h,al

    mov    ax,bx        ; convert segments to K bytes
    mov    cl,6
    shr    ax,cl

    mov    bx,40h        ; point to bios data area
    mov    ds,bx
    mov    bx,13h        ; and to memory size word in particular

    cmp    [bx],ax     ; same size?
    je    exit        ; yes-then we must have done this before

    mov    [bx],ax     ; else - update and
    push    ax

; remove comments to patch equipment flag to indicate 4 floppies attached.
; especially useful for AST RESEARCH's SUPERDRV.

;stub** mov    bx,10h        ; point to equipment flag
;stub** mov    ax,[bx]     ; get equipment flag
;stub** or    ax,00c0h    ; set installed floppy count to 4
;stub** mov    [bx],ax     ; and restore to proper spot

    pop    ax        ; get ds back but save ax on stack
    pop    ds
    push    ax

    mov    dx,offset findmem    ; tell how much memory we found
    mov    ah,9
    int    21h

    pop    ax        ; get K byte count
    call    decout

    mov    dx,offset kbytes
    mov    ah,9
    int    21h

    mov    dx,offset reboot    ; tell them about reboot
    mov    ah,9
    int    21h

    int    19h        ; re-boot

exit:
    pop    ds
    mov    dx,offset done
    mov    ah,9
    int    21h

; exit via return to caller instead of int 20h exit to DOS.
; changed 1-1-84 by Tom Perry for device driver environment.

    ret


; quick and probably dirty - display decimal in ax routine

decout:
    push    ax
    push    bx
    push    cx
    push    dx

    xor    cx,cx        ;counter of digits
    mov    bx,10        ;divide by 10 for conversion

decimal$loop:
    xor    dx,dx        ;clear for divide
    div    bx        ;get remainder and quotient
    add    dx,'00'         ;make remainder ascii
    push    dx        ;save it
    inc    cx        ;and count it
    or    ax,ax        ;out of digits?
    jnz    decimal$loop    ;no-loop on the decimal

decimal$out:
    pop    dx        ;get digit
    mov    ah,2        ;print digit
    int    21h
    loop    decimal$out    ;and loop

    pop    dx
    pop    cx
    pop    bx
    pop    ax
    ret

memdrvr endp

s0000    ends

    end