The LGP-30 was a bit serial, binary, 31 bit word computer with 4096 word drum. Standard inputs were the Flexowriter keyboard and paper tape (10 6-bit characters/second). The only printing output was the Flexowriter printer (typewriter, 10 characters/second). An optional higher speed paper tape reader and punch was available as a separate peripheral.

The LGP-30 was commonly referred to as a desk computer. It was 26 inches deep, 33 inches high, and 44 inches long, exclusive of the typewriter shelf. The computer weighed approximately 800 pounds and was mounted on sturdy castors which facilitates movement of the computer.

The computer contained 113 electronic tubes and 1450 diodes. The 113 electronic tubes were mounted on 34 etched circuit pluggable cards which also contain associated components. Although 34 pluggable cards were used, there were only 12 different types of such cards. Card-extenders were available to permit dynamic testing of all machine functions. Six hundred and eighty of the 1450 diodes were mounted on one pluggable logic board .

The LGP-30 required 1500 watts when operating under full load. The power inlet cord was plugged into any standard 115 volt 60 cycle single phase line. The computer contained internal voltage regulation of all voltages against power line variations from 95 to 130 volts. In addition to regulation of power line variations, the computer also contained the circuitry required to permit a warm-up stage. This warm-up stage minimized thermal shock to tubes and insures long component life. The computer contains its own blower unit and directs filtered air, through ducts, to tubes and diodes, in order to again insure long component life and proper operation. No expensive air conditioning needed to be installed ,if the room is kept within a reasonable temperature range.

There were 32 bit locations per drum word, but only 31 were used, permitting a "restoration of magnetic flux in the head" at the 32nd bit time. Since there was only one address/instruction, a method was needed for the optimal allocation of operands. Otherwise, each instruction might have to wait a complete drum (or disk) revolution each time a data reference is made. The LGP-30 provided for operand-location optimization by interlacing the logical addresses on the drum so that two adjacent addresses (e.g., 00 and 01) were separated by nine physical locations. These spaces allowed for operands to be located next to the instructions which use them. There are 64 tracks, each with 64 words (sectors). The time between two adjacent physical words was approximately 0.260 millisecond, and the time between two adjacent addresses was 9 x 0.260 or 2.340 milliseconds. The actual maximum access was 16.66 ms.

Half of the instruction (15 bits) was unused. It could be used for extra instructions, indexing, indirect addressing, or a second (+1) address to locate the next instruction, all of which increased the performance.

There was a small CRT display which was used for debugging. The display was in binary and consisted of three registers. {To read you counted the ups and downs of the trace.}

Word Length: 31 Bits, including a sign bit, but excluding a blank spacer bit
Memory Size: 4096 words
Speed:  0.260 milliseconds access time between two adjacent physical words; access times between two
adjacent addresses 2.340 milliseconds.
Clock Rate: 120 Khz
Power: 1500 watts
Arithmetic element: Three working registers: C the counter register, R the instruction register and A the accumulator register.
Instruction format:  Sixteen instruction using half-word format
Technology: 113 vacuum tubes and 1350 diodes.
Number Produced; 320~493
First Delivery: September, 1956
Price: $47,000
Successor: LGP-21
Achievements: With the Bendix G-15 the first of the desk-sized computers offering small scale scientific computing. 

Revolutionizing the computer industry with the potential for low-cost distributed processing.

The LGP-30 was used at a number of institutions, including Dartmouth College where students implemented Dartmouth ALGOL 30 on the machine.