Durango F-85

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Durango F-85
Manufacturer Durango Systems Corp.
Type Personal business computer
Release date 1977[1]
Retail availability 1977-1984
Media two 100 tpi high-capacity 5.25-inch diskette drives storing 480 KB on each single-sided diskette using group-coded recording (GCR}
Operating system DX-85M
CPU 5 MHz Intel 8085A
Memory 65 KB (up to 196 KB)
Storage 40 MB Shugart SA-4006 14-inch winchester
Display 9-inch CRT with 64 characters per row by 16 rows or 80 characters per row by 24, based on the Intel 8275 Video display controller
Input keyboard, full stroke, 84 key
Successor Durango "Poppy"

The Durango F-85 was an early personal computer introduced in 1977 by Durango Systems Corporation. It could run its own multitasking operating system called DX-85M, which included an integral Indexed Sequential (ISAM) file system and per-task file locking, or alternatively CP/M-80.[2][3][4] DX-85M utilized a text configuration file named CONFIG.SYS six years before this filename was used for a similar purpose under MS-DOS/PC DOS 2.0 in 1983.

The F-85 used single-sided 5¼-inch 100 tpi diskette drives providing 480 KB utilizing a high-density 4/5 group coded encoding. The machine was using a Western Digital FD1781 floppy disk controller with 77-track Micropolis drives.[5] In later models this was expanded to a double-sided option for 960 KB (946/947 KB formatted[2][1][nb 1]) per diskette.[1][3][5]

Durango later dropped the "F-85" model name and adopted a user model system, with 700 being the entry model and 950 being the full-featured model.

Still later, they designed a 80186-/80286-based 16-bit system, the Durango "Poppy"; MS-DOS was selected as the entry operating system.

See also[edit]


  1. ^ The product flyer for the Durango 800 series documents an formatted "on-line capacity" of 1.892 MB for the diskette drives. The system, however, was equipped with two 5¼-inch Micropolis 100 tpi 77-track floppy drives by default, and 1.892 MB is about twice as large as the physical drive capacity documented in various other sources (480 KB per side), therefore, by "on-line capacity" they must have meant the available storage capacity available to users for the combination of two drives.


  1. ^ a b c Comstock, George E. (2003-08-13). Hendrie, Gardner, ed. "Oral History of George Comstock" (PDF). Mountain View, California, USA: Computer History Museum. CHM X2727.2004. Archived (PDF) from the original on 2017-03-23. Retrieved 2017-03-23. 
  2. ^ a b "800 Technical Summary - 800 Series Business Computer System" (PDF). San Jose, CA, USA: Durango Systems, Inc. Archived (PDF) from the original on 2017-03-23. Retrieved 2017-03-23. 
  3. ^ a b Guzis, Chuck (October 2006). "The Durango F-85 Computer". Sydex. Archived from the original on 2017-03-23. Retrieved 2017-03-23. 
  4. ^ "What is Durango?". Computerworld: 4. 1978-10-02. 
  5. ^ a b Guzis, Chuck (2009-09-13). "Durango GCR". Sydex. Archived from the original on 2017-03-25. Retrieved 2017-03-25. 

Further reading[edit]

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