<PAGE>

                      SECURITIES AND EXCHANGE COMMISSION
                                       
                            Washington, D.C.  20549
                                       
                                ---------------
                                       
                                   FORM 10-Q
                                ---------------

          [X]       QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)
                    OF THE SECURITIES EXCHANGE ACT OF 1934

                    For the quarterly period ended January 31, 1998

          [ ]       TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d)
                    OF THE SECURITIES EXCHANGE ACT OF 1934

                    For the transition period from _______ to _______

                                       
                        Commission file number 0-21103
                                       
                   ADVANCED DIGITAL INFORMATION CORPORATION


              Incorporated under the laws          I.R.S. Identification
              of the State of Washington           No. 91-1618616


                              10201 Willows Road
                                P.O. Box 97057
                        Redmond, Washington 98073-9757
                                       
                                (425) 881-8004
                                       

Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.

                           [X] Yes          [ ] No

The total shares of common stock without par value outstanding at the end of
the quarter reported is 9,704,699.

<PAGE>

                        PART I -- FINANCIAL INFORMATION
                                       
ITEM 1.  FINANCIAL STATEMENTS
                                       
                   ADVANCED DIGITAL INFORMATION CORPORATION
                          CONSOLIDATED BALANCE SHEETS
                     JANUARY 31, 1998 AND OCTOBER 31, 1997

<TABLE>
<CAPTION>

                                                      JANUARY 31,    OCTOBER 31,
                                                          1998          1997
                                                      -----------    -----------
                   ASSETS                             (Unaudited)
<S>                                                   <C>            <C>
Current assets:
 Cash and cash equivalents.........................   $30,816,135    $32,806,822
 Accounts receivable, net of allowances
  of $364,000 in 1998 and $324,000 in 1997.........    15,975,505     18,078,302
 Inventories, net..................................    21,868,205     16,074,787
 Prepaid expenses and other........................       773,499        714,979
 Deferred income taxes.............................       767,688        767,688
                                                      -----------    -----------
  Total current assets.............................    70,201,032     68,442,578
                                                      -----------    -----------
Property, plant and equipment, at cost:
 Machinery and equipment...........................     4,717,141      4,366,343
 Office equipment..................................       457,480        417,116
 Leasehold improvements............................       419,433        415,493
                                                      -----------    -----------
                                                        5,594,054      5,198,952
 Less: accumulated depreciation and amortization...    (2,890,940)    (2,689,685)
                                                      -----------    -----------
  Net property, plant and equipment................     2,703,114      2,509,267
                                                      -----------    -----------
Deferred income taxes..............................        89,414         89,414
                                                      -----------    -----------
Investment in Crossroads Holding Corp. and other
 assets............................................     4,117,672      4,152,634
                                                      -----------    -----------
                                                      $77,111,232    $75,193,893
                                                      -----------    -----------
                                                      -----------    -----------

   LIABILITIES AND SHAREHOLDERS' EQUITY
Current liabilities:
 Accounts payable..................................   $10,849,860    $11,237,131
 Accrued liabilities...............................     1,776,236      2,594,831
 Income taxes payable..............................     2,173,242      1,252,324
                                                      -----------    -----------
  Total current liabilities........................    14,799,338     15,084,286
                                                      -----------    -----------
Committments.......................................            --             --
Shareholders' equity:
 Preferred stock, no par value; 2,000,000 shares
  authorized; none issued
  and outstanding..................................            --             --
 Common stock, no par value; 40,000,000 shares
  authorized, 9,704,699 issued and outstanding
  (9,699,824 in 1997)..............................    45,833,113     45,808,291
 Retained earnings.................................    16,840,393     14,479,104
 Cumulative translation adjustment.................      (361,612)      (177,788)
                                                      -----------    -----------
  Total shareholders' equity.......................    62,311,894     60,109,607
                                                      -----------    -----------
                                                      $77,111,232    $75,193,893
                                                      -----------    -----------
                                                      -----------    -----------

</TABLE>

    See the accompanying notes to these consolidated financial statements.

                                      3

<PAGE>

                   ADVANCED DIGITAL INFORMATION CORPORATION
                       CONSOLIDATED STATEMENTS OF INCOME
           THREE MONTHS ENDED JANUARY 31, 1998 AND 1997 (UNAUDITED)

<TABLE>
<CAPTION>

                                                          1998           1997
                                                      -----------    -----------
<S>                                                   <C>            <C>
Net sales..........................................   $22,865,661    $20,068,602
Cost of sales......................................    15,450,792     14,097,140
                                                      -----------    -----------
 Gross profit......................................     7,414,869      5,971,462
                                                      -----------    -----------
Operating expenses:
 Selling and administrative........................     3,783,719      3,047,461
 Research and development..........................       617,599        632,015
                                                      -----------    -----------
                                                        4,401,318      3,679,476
                                                      -----------    -----------
Operating profit...................................     3,013,551      2,291,986
                                                      -----------    -----------
Other income:
 Interest income...................................       321,168        115,483
 Foreign currency transaction gains................       239,988        138,231
                                                      -----------    -----------
                                                          561,156        253,714
                                                      -----------    -----------
Income before provision for income taxes...........     3,574,707      2,545,700
Provision for income taxes.........................     1,213,418        885,162
                                                      -----------    -----------
Net income.........................................   $ 2,361,289    $ 1,660,538
                                                      -----------    -----------
                                                      -----------    -----------
Basic net income per share.........................   $      0.24    $      0.21
                                                      -----------    -----------
                                                      -----------    -----------
Diluted net income per share.......................   $      0.24    $      0.20
                                                      -----------    -----------
                                                      -----------    -----------

</TABLE>

    See the accompanying notes to these consolidated financial statements.

                                      4

<PAGE>

                   ADVANCED DIGITAL INFORMATION CORPORATION
                     CONSOLIDATED STATEMENTS OF CASH FLOWS
           THREE MONTHS ENDED JANUARY 31, 1998 AND 1997 (UNAUDITED)

<TABLE>
<CAPTION>

                                                          1998          1997
                                                      -----------    -----------
<S>                                                   <C>            <C>
CASH FLOWS FROM OPERATING ACTIVITIES:
 Net income.........................................  $ 2,361,289    $ 1,660,538
 Adjustments to reconcile net income to net cash
  used in operating activities:
   Depreciation and amortization....................      212,883        172,330
 Change in assets and liabilities:
   Accounts receivable..............................    2,084,084     (2,370,560)
   Inventories......................................   (5,921,466)    (2,155,499)
   Prepaid expenses and other.......................      (61,284)        42,178
   Other assets.....................................       27,538        (20,132)
   Accounts payable.................................     (353,270)    (1,838,213)
   Accrued liabilities..............................     (782,439)       (79,145)
   Income taxes payable.............................      975,999         78,411
                                                      -----------    -----------
Net cash used in operating activities...............   (1,456,666)    (4,510,092)
                                                      -----------    -----------
CASH FLOWS FROM INVESTING ACTIVITIES:
 Purchases of property, plant and equipment.........     (426,835)      (324,338)
                                                      -----------    -----------
CASH FLOWS FROM FINANCING ACTIVITIES:
 Proceeds from issuance of common stock for stock
  options, including tax benefit....................       24,822      1,225,534
                                                      -----------    -----------
Effect of exchange rate changes on cash.............     (132,008)       (31,973)
                                                      -----------    -----------
Net decrease in cash and cash equivalents...........   (1,990,687)    (3,640,869)
Cash and cash equivalents at beginning of period....   32,806,822     10,436,783
                                                      -----------    -----------
Cash and cash equivalents at end of period..........  $30,816,135    $ 6,795,914
                                                      -----------    -----------
                                                      -----------    -----------

</TABLE>

    See the accompanying notes to these consolidated financial statements.

                                      5

<PAGE>

              NOTES TO INTERIM CONSOLIDATED FINANCIAL STATEMENTS

                               January 31, 1998
                                  (Unaudited)

NOTE 1. BASIS OF PRESENTATION

     The accompanying condensed financial statements are unaudited and should
be read in conjunction with the Advanced Digital Information Corporation
financial statements included in the Company's Annual Report on Form 10-K for
the year ended October 31, 1997. In the opinion of management, all normal
recurring adjustments which are necessary for the fair presentation of the
results for the interim periods are reflected herein. Operating results for the
three-month period ended January 31, 1998, are not necessarily indicative of
results to be expected for a full year.

NOTE 2. EARNINGS PER SHARE

          In the first quarter of 1998, the Company adopted Statement of
Financial Accounting Standards No. 128,  "Earnings per Share" ("FAS128") which
changed the Company's presentation and calculation of earnings per share. Basic
net income per share represents net income divided by the weighted average
number of shares outstanding the period. Diluted net income per share
represents net income divided by the weighted average number of shares
outstanding including the potentially dilutive impact of stock options. Common
stock options are converted using the treasury stock method. Earnings per share
for 1997 have been restated to conform to the requirements of FAS 128. The
adoption of FAS 128 did not have a material impact on the Company's earnings
per share.

          The following table sets forth the computation of basic and diluted
net income per share for the three months ended January 31, 1998 and 1997:

<TABLE>
<CAPTION>

                                                             1998           1997
                                                          ----------     ----------
<S>                                                       <C>            <C>
Numerator:
  Net income...........................................   $2,361,289     $1,660,538
Denominator:
 Denominator for basic net income per share
  -- weighted average shares...........................    9,702,064      8,040,392
 Dilutive potential common shares from
  Team Member (employee) stock options.................      200,520        204,386
                                                          ----------     ----------
 Denominator for diluted net income per
  share -- adjusted weighted average shares
  and assumed conversions..............................    9,902,584      8,244,778
                                                          ----------     ----------
                                                          ----------     ----------
Basic net income per share.............................      $  0.24        $  0.21
                                                          ----------     ----------
                                                          ----------     ----------
Diluted net income per share...........................      $  0.24        $  0.20
                                                          ----------     ----------
                                                          ----------     ----------

</TABLE>

                                      6

<PAGE>

NOTE 3. INVENTORIES

     Inventory is comprised as follows:

<TABLE>
<CAPTION>

                                                 January 31, 1998    October 31, 1997
                                                 ----------------    ----------------
     <S>                                         <C>                 <C>
     Finished Goods                                   $ 9,506,062         $ 8,231,656
     Work-in-process                                    1,621,259           1,416,067
     Raw materials                                     12,012,790           7,557,748
                                                      -----------         -----------
                                                       23,140,111          17,205,471
     Allowance for inventory obsolescence              (1,271,906)         (1,130,684)
                                                      -----------         -----------
                                                      $21,868,205         $16,074,787
                                                      -----------         -----------
                                                      -----------         -----------

</TABLE>

ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS
        OF OPERATIONS

RESULTS OF OPERATIONS

          The following discussion and analysis may contain forward-looking
statements that involve risks and uncertainties, such as statements of the
Company's plans, objectives, expectations and intentions. The Company's actual
results could differ materially from those discussed here. Such risks are
detailed in the Company's Annual Report on Form 10-K filed with the SEC in
January 1998 and are incorporated herein by reference. Readers are cautioned
not to place undue reliance on these forward-looking statements, which speak
only as of the date hereof. The Company undertakes no obligation to publicly
release the result of any revisions to these forward-looking statements that
may be made to reflect events or circumstances after the date hereof or to
reflect the occurrence of unanticipated events.

          NET SALES.  Net sales for the three months ended January 31, 1998
increased 14% to $22.9 million from $20.1 million for the same period in fiscal
1997. The increase in net sales was primarily due to strong unit sales volume
of the Company's automated tape libraries, including the Scalar products and
reflecting, in part, the introduction of the FastStor products in the final
quarter of fiscal 1997. The growth in sales related to the library sales was
offset by lower sales of standalone tape drives from the comparable quarter of
1997 and price reductions for selected parts.

          GROSS PROFIT.  Gross profit was $7.4 million or 32% of net sales 
for the three months ended January 31, 1998 compared to $6.0 million or 30% 
of net sales for the same period in fiscal 1997. Gross profit margin for the 
current three-month period was higher than the same 

                                      7

<PAGE>

period in fiscal 1997 due to a shift in product mix toward higher-margin 
Scalar libraries and the reduction in sales of the lower-margin standalone 
products.  Gross profit margins are dependent on a number of factors, 
including customer and product mix, price competition and tape drive costs.  
If the percentage of sales representing standalone and media products 
increases in the balance of fiscal 1998, the margin percentage for the period 
is likely to decline from the margin percentage achieved in the first 
quarter. In addition, there can be no assurance that the Company can improve 
upon or maintain the current gross margin levels for a given product line, in 
that tape drives purchased from third-party suppliers are a significant 
component of the Company's product costs.

          SELLING AND ADMINISTRATIVE EXPENSES.  Selling and administrative
expenses were $3.8 million or 17% of net sales for the three months ended
January 31, 1998 compared to $3.0 million or 15% of net sales for the same
period in fiscal 1997. The dollar increase in selling and administrative
expenses in the three months ended January 31, 1998 over the comparable period
in fiscal 1997 was primarily due to increased sales personnel both in the
headquarters office and in regional offices throughout the United States.  The
Company expects that selling and administrative expenses as a percentage of net
sales may decline slightly for the fiscal year ending October 31, 1998 from the
levels experienced in the three months ended January 31, 1998.

          RESEARCH AND DEVELOPMENT EXPENSES.  Research and development 
expenses were $618,000 or 3% of net sales for the three months ended January 
31, 1998 compared to $632,000 or 3% of net sales for the same period in 
fiscal 1997. The Company expects research and development spending to stay at 
approximately 3% of net sales throughout fiscal 1998.

          OTHER INCOME.  Interest income for the three months ended January 
31, 1998 was $321,000 compared to $115,000 for the same period in fiscal 
1997. This increase is the result of investing the proceeds received from 
issuance of common stock in March 1997. Net foreign currency translation 
gains increased approximately $102,000 between the comparison periods.  
Foreign currency gains or losses arise as a result of the operation of ADIC 
Europe, the functional currency of which is French francs.  ADIC Europe buys 
products from ADIC in U.S. dollars and resells a significant majority of such 
products in U.S. dollars.  However, because francs are used as the functional 
accounting currency, all monetary assets and liabilities are translated into 
francs on ADIC Europe's financial statements.  To the extent that these 
monetary assets and liabilities do not fully offset each other and the 
franc-to-U.S.-dollar exchange rate changes, transaction gains or losses may 
result.  For large sales denominated in other currencies, the Company 
attempts to implement appropriate hedging strategies.

          PROVISION FOR INCOME TAXES.  Income tax expense for the three months
ended January 31, 1998 was $1,213,000 compared to $885,000 for the same period
in fiscal 1997.  The Company believes that the 34% effective tax rate reflected
in its most recent results, which includes taxes paid in various federal, state
and international jurisdictions, is generally indicative of the Company's
effective tax rate in future periods.

LIQUIDITY AND CAPITAL RESOURCES

                                      8

<PAGE>

          The Company's operating activities used $1.5 million of cash in the
first three months of fiscal 1998. Such cash was primarily used to fund a $5.9
million increase in inventories which was offset in part by strong net income
as well as a decrease in accounts receivable and changes in other items.

          At January 31, 1998, the Company had cash and cash equivalents of
$30.8 million. As of that date, the Company also had a $10.0 million bank line
of credit that expires at the end of fiscal 1998. Any borrowings under this
line of credit would bear interest at the bank's prime rate or adjusted LIBOR
rate. No borrowings have been made under this line of credit.

          The Company believes that its existing cash and cash equivalents and
bank line of credit, together with the results of operations, will be
sufficient to fund its working capital and capital expenditure needs for at
least the next twelve months. The Company may utilize cash to acquire or invest
in businesses, products or technologies that it believes are strategic. From
time to time, in the ordinary course of business, the Company evaluates
potential acquisitions of such businesses, products or technologies. However,
the Company has no present understanding, commitments or agreements with
respect to any material acquisition of other businesses, products or
technologies.

                                      9

<PAGE>

                          PART II -- OTHER INFORMATION

Item 1.   Legal Proceedings.

          None

Item 2.   Changes in Securities.

          None

Item 3.   Defaults Upon Senior Securities.

          None

Item 4.   Submission of Matters to a Vote of Security Holders.

          At its annual meeting on February 25, 1998, duly called and with
          proxies solicited, 9,328,602 shares were represented in person or by
          proxy constituting 96.14 percent of the outstanding shares.

     i.        The proposal to approve the Advanced Digital Information
          Corporation Amended 1997 Stock Purchase Plan received the following
          votes:

<TABLE>
<CAPTION>

                                        Votes             Percent
                                       ---------          -------
               <S>                     <C>                <C>
               For                     5,233,305           53.93%
               Against                   954,526            9.84%
               Abstain                    39,108             .40%
               Broker Non-Votes        3,101,663           31.97%

</TABLE>

          The foregoing proposal was approved.

     ii.       The proposal to amend the Advanced Digital Information
          Corporation 1996 Stock Option Plan received the following votes:

<TABLE>
<CAPTION>

                                     Votes             Percent
                                    ---------          -------
               <S>                  <C>                <C>
               For                  5,625,287           57.97%
               Against                556,721            5.74%
               Abstain                 44,931             .46%
               Broker Non-Votes     3,101,663           31.97%

</TABLE>

          The foregoing proposal was approved.

     iii. Two directors were reelected to the Board, each to hold office for a
          three-year term. Each nominee received not less than 8,512,617 votes,
          which represents 91.25 percent of the shares voted.

                                      10

<PAGE>

Item 5.   Other information.

          On February 25, 1998, the Company's Board of Directors adopted a
          resolution increasing the size of the Board to seven members, and
          elected Mr. Tom A. Alberg (age 57) to fill the resulting vacancy.
          Since January 1996, Mr. Alberg has been a principal of Madrona
          Investment Group LLC, a private merchant banking firm. Mr. Alberg was
          the President, Chief Operating Officer and a Director of LIN
          Broadcasting Corporation, a cellular telephone company, from April
          1991 to October 1995, and the Executive Vice President of AT&T
          Wireless Services, formerly McCaw Cellular Communciations, Inc. from
          July 1990 to October 1995. Prior to July 1990, Mr. Alberg was
          Chairman of the Executive Committee and a partner in the law firm of
          Perkins Coie, Seattle, Washington. Mr. Alberg is also a director of
          Active Voice Corporation, Amazon.com, Inc., Emeritus Corporation,
          MOSAIX, Inc. and Visio Corporation.

Item 6.   Exhibits and Reports on Form 8-K.

          None

                                      11

<PAGE>

                                   SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.


                                   ADVANCED DIGITAL INFORMATION CORPORATION


Dated: March 13, 1998              ----------------------------------------
                                   Peter H. van Oppen, Chairman
                                   and Chief Executive Officer


Dated: March 13, 1998              ----------------------------------------
                                   Leslie S. Rock, Treasurer
                                   and Chief Accounting Officer

                                      12