Durango F-85

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.^[1][2][3] 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.^[1][4][5] 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.

Durango F-85

Logo of Durango Systems
Manufacturer	Durango Systems Corporation
Type	Personal business computer
Release date	September 1978[1][2]
Lifespan	1978-1984
Media	two 100 tpi high-capacity 5.25-inch diskette drives storing 480 KB on each single-sided or 960 KB on double-sided diskettes using group-coded recording (GCR)
Operating system	DX-85M (multi-user/multitasking)
CPU	5 MHz Intel 8085A
Memory	65 KB (up to 196 KB)
Storage	40 MB Shugart SA-4006 14-inch winchester, later 5.25" integrated ST506-interface MFM drive
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 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^{[2][4][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

• Group coded recording

Notes

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.