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system, Texas Instruments provides four major
program-development tools: interactive text editor,
macro assembler, link editor, and debug package.
Each of these operates under SCI and is easily
invoked by operator commands.
Communications Software
The OXI0 3780 Emulator provides the OS99O family
of commercial systems with a means of remote-job-
entry (RJE) communications with an IBM 360/370
host computer or another 3780 emulator-equipped
990 computer. Operation of the IBM 3780 Oata
Communications Terminal is emulated. OS990
systems so equipped can operate in unattended mode
as central or satellite stations in a distributed
network. Optional auto-call capability is also
provided. Oata files are transmitted over leased
point-to-point or switched telephone lines at speeds
up to 9600 baud. Any file or system device can be
specified to transmit or receive data. Hardware
support of 3780 emulation is provided with the 990
communications interface module to a customer-
supplied modem or Texas-Instruments-supplied
modem kit and optional auto-call unit.
DS990 Hardware
The DS990 disk-based systems require a fast, flexible
computer architecture to meet the processing
demands of multiple interactive operations. The
Model 4, Model 6, and Model 8 Systems are based
on a minimum 128K-byte 990 processor with 16K
random-access-memory (RAM) technology. The
processor features the TILINE· asynchronous, high-
speed data bus and a memory-mapping technique
that allows addressing of up to 2048K bytes of main
memory.
AU-models employ
moving...Jtead-
disk drives with
at least one removable disk pack and one additional
fixed or removable disk pack. This allows copy,
backup, and transportability of media that are so
important in interactive systems.
Each system includes one 1920-character video
display terminal and keyboard. A dual-terminal
controller is included and allows the easy addition of
a second VDT. Additional VDTs are available as
options.
990 Processor
The 128K-byte 990 processor features an advanced
memory-to-memory architecture and TILINE
asynchronous, high-speed data bus. Current models
offer main-memory capacities up to 384K bytes of
metal-oxide-semiconductor (MOS), 16K dynamic-
*TILINE is a registered trademark of Texas Instruments.
4
RAM, error-checking-and-correcting (ECC) memory.
The additional ECC memory is available in various
module sizes. TILINE expansion to a second chassis
is recommended for these memory modules. Memory
can be further expanded by adding standard 990
options.
The 990 processor includes a dual input/ output
system, a high-speed, asynchronous parallel TILINE
bus, and a low- to medium-speed command-driven
communications register unit (CR U).
TILINE Peripherals
TILINE peripherals are high-speed I/O systems
which transfer data to and from 990 memory at
rates that approach the instruction execution rate of
the 990 computer.
The DS990 base system includes one of the
following disk systems, depending on the model
selected. The DS31 Disk System has a 2315-type disk
cartridge with 2.8M bytes of formatted capacity.
This disk drive is an option on the Model 6 and
Model 8 Systems.
The OSlO Oisk System has a single-spindle, fixed-
and femovabie-piaUer disk drive employing the 5440-
type disk cartridge. Each platter has a 4.7M-byte
capacity for a combined disk-drive capacity of 9.4M
bytes. This is the disk drive supplied with the Model
4 System and is offered as an option on the Model
6 and Model 8 Systems. One DS I 0 disk controller
can accommodate up to two DS I 0 disk drives.
The DS25 Disk System has a multiplatter disk
pack with 22.3M bytes of formatted capacity. Dual
DS25 disk drives are employed on the Model 6
System. One OS25 disk controller can accommodate
up to four DS25 disk drives.
The . DS50 . . Disk. System . .
has.amllltiplatter·
disk
pack with 44.6M bytes of formatted capacity. Dual
OS50 disk drives are employed on the Model 8
System. One OS50 disk controller can accommodate
up to four DS50 disk drives.
The Model 979A Magnetic-Tape Transport is an
optional TILINE peripheral. Two versions are
available: an 8OO-bits-per-inch, nonreturn-to-zero
format and a 1600-bits-per-inch, phase-encoded
format. Both versions use industry-compatible, nine-
track tape formats. The transport operates at 953
millimetres per second (37.5 inches per second).
CRU Peripherals
The command-driven communications-register-unit
(CRU) peripherals are low- to medium-speed I/O
systems that transfer data to and/ or from the 990
processor. These peripherals are optional features
that further enhance the DS990 system.
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