The 316 succeeded the earlier DDP-516 model and was promoted by Honeywell as suitable for industrial process control, data-acquisition systems, and as a communications concentrator and processor. The computer processor was made from small-scale integration
DTL monolithic silicon
integrated circuits. Most parts of the system operated at 2.5 MHz, and some elements were clocked at 5 MHz. The computer is a bitwise-parallel
2's complement system with 16-bit
word length. The
instruction set was a single-address type with an index register. Initially released with a capacity of 4096 through 16,384 words of memory, later expansion options allowed increasing memory space to 32,768 words. Memory cycle time is 1.6 microseconds; an integer register-to-register "add" instruction takes 3.2 microseconds. An optional hardware arithmetic option was available to implement integer multiply and divide, double-precision load and store, and double-precision (31-bit) integer addition and subtraction operations. It also provides a normalization operation, assisting implementation of software
floating-point operations. The programmers' model of the H-316 consists of the following registers: • The 16-bit
A register is the primary arithmetic and logic accumulator. • The 16-bit
B register is used for double-length arithmetic operations. • The 16-bit
program counter holds the address of the next instruction. • A
carry flag indicates arithmetic overflow. • A 16-bit
X index register provides for modification of the address of operands. The
instruction set has 72 arithmetic, logic, I/O and flow-control instructions. Input/output instructions use the
A register and separate input and output 16-bit buses. A 10-bit I/O control bus, consisting of 6 bits of device address information and 4 bits of function selection, is used. The basic processor has a single interrupt signal line, and an option provided up to 48 interrupts. In addition to a
front-panel display of lights and toggle switches, the system supports different types of input/output devices. A
Teletype Model 33 ASR teleprinter can be used as a console I/O device and (in the most basic systems) to load and store data to
paper tape. Smaller systems typically use a high-speed paper-tape reader and punch for data storage. The Honeywell family of peripherals included card readers and punches, line printers, magnetic tape, and both fixed-head and removable hard disk drives. A rack-mounted configuration weighs around and used 475 watts of power. Honeywell advertised the system as the first minicomputer selling for less than $10,000. The Honeywell 316 has the distinction of being the first computer displayed at a computer show with semiconductor
RAM memory. In 1972, a Honeywell 316 was displayed with a semiconductor RAM memory board (they used core memory previously). It was never placed into production, as
DTL was too power-hungry to survive much longer. Honeywell knew that the same technology that enabled the production of RAM spelled the end of DTL computers, and wanted to show that the company was cutting edge. File:Honeywell-316-01.jpg|Front panel of H316 in a desktop case File:Honeywell H316 front.jpg|Rack-mounted version of H316 ==System software==