The Durango was built by Durango Systems, Inc in San Jose, CA. It came with a 8085 processor running at 5 MHz, 64K memory as standard and could be expanded to 128K in the multiuser version.
The F-85 was marketed as a portable computer with integrated 180 cps dot matrix printer, two floppy disc drives and a 9" monitor. Well, only very strong users could carry it ;-)
The Durango ran a proprietary operating system, DX-85, as well as CPM. DX-85 had multiuser extensions and the business applications were supported by a proprietary ISAM handler. In addition to the system user, 4 users could hook up via video terminals on serial connections. These users could run programs in their allocted memory space on the F-85. Some interprocess communications were available.
More information from Chuck Guzis who was involved in the development of the Durango operating system:
• The basic system came with 64K of parity-checked DRAM; an optional 64K
or 128K of parity-checked DRAM was optional. When the additional memory
was added, a bipolar mapping RAM was also included that divided the 64K
memory space of the 8085 into 64 1K pages. Any page of physical memory
could be mapped to one or more page locations.
• Only an IEC power connector and 9 pin DIN CRT connector and 37-pin DIN
external floppy connector were present on the basic unit. However, options
included an IEEE-488 interface, 4-port serial interface and
async/sync/bisync serial communications, so the number of external
connectors could vary.
• The standard floppy configuration was 2 100 tpi 5.25" group-coded
floppy drives, each storing 980KB on a DSDD floppy. The data encoding was
Durango-proprietary. Early systems interfaced to the then-new Shugart 14
inch Winchester drive via a modified IEEE-488 protocol. Capacity of these
drives varied from 7 to 40Mb. Later systems replaced one of the floppy
drives with a 5.25" hard drive of between 7 and 40MB. An optional 2-drive
floppy external unit was available as an option; the F-85 could support up
to a maximum of 4 floppy drives.
• In addition to the extensions mentioned above, the integrated
dot-matrix printer could be upgraded from a single-pass 2 monospaced font
mode to a multipass high-quality print mode with downloadable font sets.
In this case, the printer ribbon was changed to mylar film instead of linen
and the carriage drive, printhead and electronics were upgraded. The
printer could feed standard perforated forms or be switched to a friction
feed for printing on standard stationery.
• The CRT was a 9 inch unit that was placed on top of the floppy drive part
of the system.
• The standard operating system was called DX-85M, a multi-user multitasking
system, which interfaced to up to 4 additional users by means of terminals
(made by Beehive) connected to the serial multicomm interface. It included
most standard file management capabilites as well as an integrated ISAM
file system. It was not necessary to regenerate the system when the
hardware configuration changed; the necessary extensions were loaded at
• There were two busses used, one in the main system card cage, which was
loosely based on the Intel Multibus and one used in the smaller auxiliary
card cage located behind the floppy drives, which was a proprietary 100-pin
• The standard programming language was a compiled version of BASIC called
Star-Basic. Almost all applications and utilities were written in this
language, which compiled source code to byte codes.
• CP/M 2.2 was available as an option. There was a project to include MP/M 2.0, but was discontinued when Durango began work on its Unix-based Poppy
• A standard set of business applications was available including GL, AP, AR,
Inventory, Payroll, Word Processing and a spreadsheet.
• Durango's philosophy was to provide the customer with a complete system
with all needed applications and customer support included.
• Around 1980, a marketing change was made and the F-85 was re-named the 800; a cost-reduced version with a slower printer (really just a different set of firmware) was called the 700 and the multitasking model with extra
memory and high-resolution printer was called the 900. In fact, any model
could be changed to any other in the field.
• Sometime in 1982, Durango merged (or was purchased by) Molecular Systems,
which subsequently became insolvent and was dissolved in 1984. At that
time, Durango was attempting to market its 16-bit 80186/80286
dual-processor Unix/MS-DOS system, but could not compete against the new
IBM-compatible PCs that had been introduced.
I was involved in the development of the operating system; I wrote the ISAM
file manager and the floppy disk drivers. I was in charge of the Star
Basic language and was responsible for its design and implementation. I
also designed the bank-switching mechanism for the add-on memory. I also
did the CBIOS adaptation for CP/M 2.2.