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Percom Data Company, Inc.
Garland, Texas     1976-1985

10 June 2023

Harold Mauch, Percom Data Company, Inc, Texas, 1976-1985 Click images for larger view

Percom Data Co was a small tech company in Garland Texas formed in the mid-70s by Harold Mauch and wife Lucy. Percom built cassette interfaces, disk drives, various adapters, video boards and SS50 bus products. This site is a remembrance of the company, its products, and its people.

This site is also an archive of Percom product information.


Percom Website Index

On this page you'll find a company history, product history, time line, Kansas City Standard info, buildings, acquisitions, trade shows, people and more.

See this index of all Percom information on this website including hardware and software product archives.

Help us if you can

This Percom preservation project is looking for products, software and manuals to document. If you have something you're willing to share contact us at ROGER at ARRICK dot COM

Thanks to Frank Wilson for donating a well-preserved CIS-30+ cassette interface complete with documentation.

Thanks to Wayne Smith for donating Doubler prototypes.

Connect with us

This website is maintained by Margo and Roger Arrick with help from others who cherish these old memories about a great company with great people in an amazing time. Thank you Lucy and Harold who worked so hard to make it all happen.

We're always excited to hear about those who worked at Percom back in the day. At one point there were 150 employees so there are many of you out there. Contact Roger or Margo Mauch Arrick at ROGER at ARRICK dot COM.

Percom has a Facebook group at

Percom logo

History of Percom

Sole-Proprietorship: March 1976
Incorporation: 23 January 1978 in Texas
Dissolution: 31 October 1985

Harold (AKA Hal) graduated from John Brown University in Arkansas with an electrical engineering degree. He worked at a radio station in Nebraska for a while then moved the family (wife and a small daughter) to Garland Texas in 1966. He did design work for Collins radio, then Texas instruments, then International Computer Products until 1972 when he switched to consulting work.

Harold was an electronics tinkerer and followed the hobby computer market through a local computer club and trade magazines. In 1976 Byte Magazine sponsored a gathering of technical people to define a standard for exchanging data on cassettes between small computers. Harold attended, along with Bill Gates and others - this became known as the Kansas City Cassette Standard - see below.

Later in 1976 Harold decided to start a small company to build cassette interfaces and Percom Data was born. He put a small building in the back yard for his office and to start production. Lucy did accounting and order processing while she worked full time at Xerox.

See this newspaper article with Margo in 1977. This picture was shot in the backyard building.

The cassette interfaces were a hit and in their 2nd year they sold about $90k worth of product. In 1977 Percom moved to a small building on Barnes Street and Percom incorporated.

During this time Harold was looking to the next step for personal computer storage and that was mini-floppy disk drives. Regular floppy disks of the time were 8" and mini-floppy disks were 5.25". He started out by making a disk drive system for SS50 hobby computers then in 1978 Percom started offering disk drives for the Tandy/Radio Shack TRS-80 computer. This was another hit and in 1979 Percom was approved for a modest $66k SBA loan and moved to a larger 10,000 square foot building a little further down the road. Sales were just over $500k.

Percom hired people to do order processing, engineering and sales, and Lucy went full time running the accounting department and overseeing the company financials and payroll.

After more growth in 1980 and 1981 sales went to 7 digits, and in 1982 Percom moved to a giant 27,000 square foot building just over the border in Dallas. Harold pursued engineering of hard drive systems for personal computers. In the middle of 1981 the employee count stood at approximately 65.

Access Unlimited was created as a retail and mail-order front for Percom's products outside of their normal dealer network. There were 2 stores, one on Central Expressway in Dallas.

During this time, very rapid growth resulted in a lot of financial pressure as receivables and payables and inventory ballooned. It was decided at that point to seek outside investments and John Adel purchased part of Percom. Adel added several to top management and courted additional investment to fund the growth.

In late summer of 1982 Harold became sick, received a diagnosis of leukemia, and passed at the end of August. Naturally this was a shock for everyone at Percom, his family, and a multitude of friends and business acquaintances who flooded the mailbox with cards.

1982 finished off at just over $3m in sales with 104 employees. This was a very fast-moving time in the tech industry with a lot of consolidation and companies going out of business as the IBM PC completely changed the market landscape.

In 1983 Percom sales were approaching $10m with Atari and IBM drives. Private placement efforts were launched with the ultimate plan of going public. Total employees were 160 as of April. Percom acquired 40% of Lantech, writers of the uNETix operating system for the PC to go along with Percom's new network hardware.

In 1984 sales took a downturn as part of the video game crash which you can read more about at Wikipedia. There was also a general upheaval in the personal computer market as tech switched towards the IBM PC and their clones. It was sort-of a market melt-up. At that time Percom was relying on Atari disk systems sales and the IBM drives faced tough competition. It was hoped that networking would provide an opening but competition was fierce and the technical hurdles immense.

Later in 1984 Esprit Systems of Melville, N.Y agreed to acquire Percom and the Xitex STD bus division that Percom acquired earlier was dissolved.

In May of 1985 Percom declared chapter 11 bankruptcy, and later on October 31 1985 Percom was dissolved.

There's a lot I don't know about the final couple years of Percom but I do know that it was a time of huge changes for the tech industry and many thousands of companies went out of business or merged. Percom had all the right stuff to be something big, but few companies survived that era - there was quite a bit of randomness in who the industry winners turned out to be.

Product-wise, Percom hit several home-runs starting with cassette interfaces, TRS80 drives, Separator and Doubler boards, then Atari drives - it was an amazing run, and a wild ride for everyone involved.

See the Percom Time Line and the Percom Website Index.


It's fun to see how the slogans developed over time -

1976-1981 Percom Slogans 1981 Percom Slogans 1982 Percom Slogans Percom Slogans Percom Slogans 1983 Percom Slogans

Harold A. Mauch and Lucy

Harold's family is originally from Wyoming. He attended John Brown University in Arkansas to study Engineering. That's where he meet Lucy. Harold worked at a radio station in Nebraska where the couple had their daughter Margo. In 1966 the family moved to Garland Texas where Harold worked for Collins Radio and did consulting while Lucy worked a Xerox. See more on Harold's page. Harold Mauch Here's a TV interview with Harold at a trade show in Dallas, possibly 1977. Harold Mauch Interview

Here's Lucy with Don Maxwell at COMDEX Fall 1982. See Lucy's page.

Lucy Mauch

The Kansas City Cassette Standard

As hobby personal computers came on the scene in the mid-70s there grew a need to standardize data storage so software and data could be shared between users and distributed from software writers. Reliability was also a big problem.

In 1976, Byte magazine sponsored a gathering of industry movers in Kansas City, MO to define a standard encoding scheme for cassette tapes which became known as the Kansas City Standard. The gathering included Harold Mauch of Percom, Bill Gates of MITs (this was pre-Microsoft), and many others. Harold refers to the scheme as KC-Standard/Bi-Phase-M double frequency encoding. Kansas City Cassette at Wikipedia.

Harold's explanation of the cassette standard appeared in March 1976 edition of Byte magazine under the company name of Pronetics which was right before Percom was created and the Cassette interface products launched - Here's a PDF of that article.


Percom's products started in fall of 1976 with the CI-810 cassette interface board advertised in Byte Magazine using Harold's circuitry he designed to meet the Kansas City Standard. Cassette interfaces grew then the disk drive systems appeared for hobby computers, then later for TRS80 computers, Atari computers, Heathkit, IBM and others.

See the Percom hardware and software page for more info.

Percom CIS-30+ Cassette Interface


Buildings from start to finish:
1: Portable building in backyard of Harold and Lucy's home on Windsor in Garland. (1976)
2: Small retail shop on Barnes Dr. in Garland. (Nov 77 - May 79)
3: 10k sf industrial building at 211 Kirby St. in Garland (May 79 - Jan 82)
4: 2k sf office space on Shiloh Rd. In Garland (May 80 - Jan 82)
5: 27k sf industrial building on Pagemill Rd in Dallas (May 82 - Jan 84)
6: I remember something about a building on Floyd St but none of us can remember what it was
7: Industrial building on National Place in Garland (Jan 84 - Oct 85)

See the Percom buildings page for more info.

Percom Data on Kirby St Garland TX

Access Unlimited

Access Unlimited was a mail-order and retail business set apart from Percom for distributing products direct to customers outside of the dealer networks. There were 2 storefronts - one was at 401 North Central Expressway #600 and the other was at 10503 Forest Lane near Percom - both Dallas. Sam and Connie were the main operators. Col Joe Levinson was manager over this for a while and he had one of the first car phone systems in the trunk of his Cadillac.

Access also sold iBEX computers from MARTEC International Electronics Corporation that ran CP/M.

See the Access Unlimited archive.

Access Unlimited

Trade Shows

This is Harold at the 1979 Philadelphia computer show. Percom had booths and several shows over the years and here are some pictures.



Around January of 1983 Percom acquired Xitex, a manufacturer of STD Bus CP/M computer systems. Steve Kriss was the President. Xitex was run as a subsidiary. The company stayed at their address just down the road from Percom at 9861 Chartwell Dr. Dallas TX 75243. See the Xitex archive.


Early in 1983 Percom took a 40% ownership interest in Lantech Systems, the developer of uNETix which was a Unix-like network operating system for PC's. The goal was to maximize synergy between uNETix and Percom's new network interface board called PercomNet. Offices for this company were at the Chartwell address previously occupied by Xitex. I remember they had a shiny new laser printer that cost $18k. See the uNETix archive. See the Lantech archive.


At one point Percom had about 150 employees Here are some pictures.


We've received various stories about Percom over the years which you can read here.

And here's Roger Arrick's Story of working at Percom in the early days.

2001 Company Picnic

In 2000 Margo started organizing a picnic for alumni of Percom. It took a lot of work to get it all together but the results were very good. Here are some pictures.

Percom 2001 picnic

The End

I'm looking for someone to interview who can explain more details about what happened in the last year or so of Percom's existence - 1983-1985. ROGER at ARRICK dot COM


Copyright © Roger Arrick