We recorded inventory write-downs of $95 and $137 for the years ended December 31, 2020 and 2019, respectively. The inventory write-downs were for lower of cost or market and excess and obsolescence exposure. The inventory write-downs were offset by sales of previously written-down inventory of $29 and $35 for the years ended December 31, 2020 and 2019, respectively.


	December 31,
	2020		2019
Equipment, furniture and fixtures	$	8,889	$	8,494
Tooling	6,298		6,552
Software	5,711		6,428
Leasehold improvements	1,393		1,392
	22,291		22,866
Accumulated depreciation and amortization	(17,188)		(18,258)
Property and equipment, net	$	5,103	$	4,608

Software amortization was $1,174 and $1,320 for the years ended December 31, 2020 and 2019, respectively. Depreciation and amortization expense for equipment, furniture, fixtures, tooling and leasehold improvements was $2,227 and $2,300 for the years ended December 31, 2020 and 2019, respectively.

Other assets consist primarily of deposits, deferred tax assets and licensed technology. Amortization of licensed technology was $336 and $217 for the years ended December 31, 2020 and 2019, respectively.


	December 31,
	2020		2019
Developed technology	$	5,050	$	5,050
Customer relationships	1,270		1,270
Backlog and tradename	410		410
	6,730		6,730
Less: accumulated amortization	(5,523)		(4,026)
Acquired intangible assets, net	$	1,207	$	2,704

Intangible assets are amortized over the following estimated useful lives: developed technology and customer relationships, 3 to 5 years; tradename and backlog, 6 to 18 months. Backlog was fully amortized as of December 31, 2018 and tradename was fully amortized as of December 31, 2019.

Amortization expense for intangible assets was $1,496 for the year ended December 31, 2020, with $1,192 included in cost of revenue and $304 included in selling, general and administrative on the consolidated statements of operations. As of December 31, 2020, future estimated amortization expense is as follows:

Acquired intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Conditions that would trigger an impairment assessment include, but are not limited to, past, current, or expected cash flow or operating losses associated with the asset. There were no such triggering events requiring an impairment assessment of other intangible assets as of December 31, 2020.


	December 31,
	2020		2019
Accrued payroll and related liabilities	$	2,867	$	3,440
Operating lease liability, current	2,039		1,545
Current portion of accrued liabilities for asset financings	786		483
Accrued costs related to restructuring	630		66
Accrued commissions and royalties	474		663
Accrued interest payable	429		397
Deferred revenue	179		146

Other	2,048		1,952
Accrued liabilities and current portion of long-term liabilities	$	9,452	$	8,692

On December 21, 2010, we entered into a Loan and Security Agreement with Silicon Valley Bank (the "Bank"), which was amended on December 14, 2012, December 4, 2013, December 18, 2015, December 15, 2016, July 21, 2017, December 21, 2017, December 18, 2018, December 18, 2019, April 17, 2020 and December 14, 2020 (as amended, the "Revolving Loan Agreement"). The Revolving Loan Agreement provides a secured working capital-based revolving line of credit (the "Revolving Line") in an aggregate amount of up to the lesser of (i) $10,000, or (ii) $2,500 plus 80% of eligible domestic accounts receivable and certain foreign accounts receivable. The Revolving Line has a maturity date of March 26, 2021. In addition, the Revolving Loan Agreement provides for non-formula advances of up to $10,000 which may be made solely during the last five business days of any fiscal month or quarter and which must be repaid by the Company on or before the fifth business day after the applicable fiscal month or quarter end.

Amounts advanced under the Revolving Line bear interest at an annual rate equal to the lender's prime rate plus 0.25%. The Revolving Loan Agreement, as amended also provides an option for LIBOR advances that bear interest based on the LIBOR rate, subject to the availability of a LIBOR rate. Interest on the Revolving Line is due monthly, with the balance due on March 26, 2021, which is the scheduled maturity date for the Revolving Line.

The Revolving Loan Agreement, as amended contains customary affirmative and negative covenants, including with respect to the following: compliance with laws, provision of financial statements and periodic reports, payment of taxes, maintenance of inventory and insurance, maintenance of operating accounts at the Bank, the Bank's access to collateral, formation or acquisition of subsidiaries, incurrence of indebtedness, dispositions of assets, granting liens, changes in business, ownership or business locations, engaging in mergers and acquisitions, making investments or distributions and affiliate transactions. The covenants also require that the Company maintain a minimum ratio of qualifying financial assets to the sum of qualifying financial obligations.

The Revolving Loan Agreement, as amended also contains customary events of default, including the following: defaults with respect to covenant compliance, the occurrence of a material adverse change, the occurrence of certain bankruptcy or insolvency events, cross-defaults, judgment defaults and material misrepresentations. The occurrence of an event of default could result in the acceleration of the Company's obligations under the Revolving Loan Agreement, as amended and an increase to the applicable interest rate, and would permit the Bank to exercise remedies with respect to its security interest.

To secure the repayment of any amounts borrowed under the Revolving Loan Agreement, as amended, the Company granted to the Bank a security interest in substantially all of its assets, excluding its intellectual property assets. The Company has agreed not to pledge or otherwise encumber its intellectual property assets without prior written permission from the Bank.

On April 25, 2020, we entered into a loan with Silicon Valley Bank as the lender in an aggregate principal amount of $796 (the “Loan”) pursuant to the Paycheck Protection Program (the “PPP”) under the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”).

The Loan is evidenced by a promissory note (the “Note”) dated April 25, 2020, and matures 2 years from the disbursement date. The Note bears interest at a rate of 1.000% per annum, with the first six months of interest deferred. Principal and interest are payable monthly commencing 6 months after the disbursement date and may be prepaid by the Company at any time prior to maturity with no prepayment penalties. The Note contains customary events of default relating to, among other things, payment defaults or breaches of the terms of the Note. Upon the occurrence of an event of default, the Lender may require immediate repayment of all amounts outstanding under the Note.

Under the terms of the CARES Act, PPP loan recipients can apply for and be granted forgiveness for all or a portion of loans granted under the PPP. The Loan is subject to forgiveness to the extent proceeds are used for payroll costs, including payments required to continue group health care benefits, and certain rent, utility, and mortgage interest expenses (collectively, “Qualifying Expenses”), pursuant to the terms and limitations of the PPP. We used the Loan amount for Qualifying Expenses. During the fourth quarter of 2020, we applied for and received full forgiveness and have recorded a gain of $796 within other income in our consolidated statements of operations.