Durango F-85

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Durango F-85
ManufacturerDurango Systems Corp.
TypePersonal business computer
Release dateSeptember 1978[1][2]
Mediatwo 100 tpi high-capacity 5.25-inch diskette drives storing 480 KB on each single-sided diskette using group-coded recording (GCR)
Operating systemDX-85M
CPU5 MHz Intel 8085A
Memory65 KB (up to 196 KB)
Storage40 MB Shugart SA-4006 14-inch winchester
Display9-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
Inputkeyboard, full stroke, 84 key
SuccessorDurango "Poppy"

The Durango F-85 was an early personal computer introduced in September 1978 by Durango Systems Corporation, a company started in 1977 by George E. Comstock, John M. Scandalios and Charles L. Waggoner, all formerly of Diablo Systems.[3][1][2] The F-85 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.[4][5][1] DX-85M utilized a text configuration file named CONFIG.SYS[5] five 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.[6] In later models this was expanded to a double-sided option for 960 KB (946/947 KB formatted[4][2][nb 1]) per diskette.[2][5][6][7]

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 a 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 Schultz, Brad (1978-10-02). "Business Mini Weighs 65 Pound - What is Durango?". Computerworld. CW Communications, Inc. XII (40): 1, 4. Retrieved 2017-06-13.
  2. ^ a b c d Comstock, George E. (2003-08-13). "Oral History of George Comstock" (PDF). Interviewed by Hendrie, Gardner. Mountain View, California, USA: Computer History Museum. CHM X2727.2004. Archived (PDF) from the original on 2017-03-23. Retrieved 2017-03-23. […] that's how we got Durango Systems started in 1977. And we opened the doors for business I think it was July or August of '77 and began designing a product, one of which is sitting right there. That's the Durango F85 computer […] We were on the startup of Durango, we raised our money and got going and in that case it took us another 15 months to start shipping product […]
  3. ^ "CI News: Play it again, George?". Computerworld. Computerworld, Inc. XI (47): 64. 1977-11-21. Retrieved 2017-06-13.
  4. ^ 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.
  5. ^ a b c Guzis, Charles P. (October 2006). "The Durango F-85 Computer". Sydex. Archived from the original on 2017-03-23. Retrieved 2017-03-23.
  6. ^ a b Guzis, Charles P. (2009-09-13). "Durango GCR". Sydex. Archived from the original on 2017-03-25. Retrieved 2017-03-25.
  7. ^ "NCC Preview: OEMs at NCC - Micropolis Corp". Computerworld. CW Communications, Inc. XII (22): P/50. 1978-05-28. Retrieved 2017-06-12. […] Micropolis has extended the capacity of 5.25-in. floppy disk subsystems via double-sided models with formatted file storage of up to nearly 2 million bytes […] The Megafloppy series also features an intelligent controller that facilitates interconnection of four subsystems to a common host interface for a total on-line storage capacity of more than 15M bytes […] Double-sided versions of the product line will be implemented first in two OEM series - Model 1015 and Model 1055 […] The Model 1015 is an unpackaged drive designed for the manufacturer who integrates floppy disk storage into his own system enclosure. A range of storage capacities from 143,000 to 630,000 bytes per drive is available […] Model 1015 customers have the option of using the Micropolis intelligent controller and Group Code Recording (GCR) method to further expand file space up to 946,000 bytes […] Offering GCR and a microprocessor-based controller as standard features, the Model 1055 5.25-in. floppy has four soft-sectored formats for each of its 77 tracks, yielding a maximum capacity of 1,892,000 bytes of file space on its double-sided version […] An add-on module available for the 1055 is comprised of two read/write heads and two drives, sharing a common controller. The subsystem capacity (formatted) with the module is 3,784,000 bytes […] Up to four 1055s, each with an add-on module, can be daisy-chained to a common host for a maximum on-line storage capacity of more than 15M bytes […]

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