(Mirrored without permission from http://www.users.nwark.com/~rcmahq/jclark/lgp30.htm)
{Pictured above left to right are the papertape reader/punch, the flexowriter, and the LGP-30 computer makeing up the computer system at OCC in 1960.}
================ From the Programming Class Notes ======================
LGP-30 PHYSICAL DESCRIPTION
The LGP-30 is commonly referred to as a desk computer. Obviously, this phrase originated because the size of the LGP-30 closely parallels the size of a standard office desk. The LGP-30 is 26" deep, 33" high, and 44" long, exclusive of the typewriter shelf. The computer weighs approximately 800 pounds and is mounted on sturdy casters which facilitates movement of the computer.
Another asset in regard to the computer's mobility is its power requirement. The LGP-30 requires 1500 watts when operating under full load. The power inlet cord may be plugged into any standard 115 volt 60 cycle single phase line. The computer contains 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 contains the circuitry required to permit a warm-up stage. This warm-up stage minimizes 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 needs to be installed ,if the room is kept within a reasonable temperature range.
The computer contains 113 electronic tubes and 1450 diodes. The 113 electronic tubes are mounted on 34 etched circuit pluggable cards which also contain associated components. Although 34 pluggable cards are used, there are only 12 different types of such cards. Card-extenders are available to permit dynamic testing of all machine functions. Six hundred and eighty of the 1450 diodes are mounted on one pluggable logic board. This logic board may be quickly removed and is very accessible for service personnels use.
The main memory consists of a magnetic drum that contains 4096 words. An instruction or data word may be stored in each one of the 4096 available words. When instructions are placed on the drum, they will be executed in sequence until one of the instructions "transfers control" to a new set of instructions.
============================================================================
The LGP-30 could do a GILL calcualtion in 36.0 milliseconds. It rented for $1,100 and sold for $39,600 in 1957. Seven units were produced in 1956. The first installiation was in Sept 1956 in Pasadena, CA.
The LGP-30 had 16 instructions
OP-CODE SYMBOL FUNCTION OP-CODE SYMBOL FUNCTION 0000 Z STOP 1000 P PRINT 0001 B BRING 1001 E EXTRACT 0010 Y STORE ADDRESS 1010 U UNC-TRANSFER 0011 R RETURN ADDRESS 1011 T TEST 0100 I INPUT 1100 H HOLD 0101 D DIVIDE 1101 C CLEAR 0110 N MULTIPLY 1110 A ADD 0111 M MULTIPLY 1111 S SUBTRACT
The LGP-30 had a "Psudo" 32 bit accumulator which was stored on the drum memory. Actually it had 32 such accumulators on one track of the drum and in the multiplication functions a 64 bit product was stored. The 'M' or 0111 multiply would give you the first 32 bits of the product while the 'N' or 0110 multiply would work the last 32 bits.
All calculations were in pure binary. Real values were faked as integer and the programmer had to take care of the bit point or the 'Q' for each value.
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.}
Location Counter Last Instruction executed Accumulator
Since this writer has been trained on an IBM 650, the LGP-30 was not very impressive. However the flexowriter was an impressive unit. With it you could cut a paper tape as you filled out a form, and then use that tape to fill out similar forms. In Fall 61 this writer used the system to complete several four page applications for National Science Foundation Academic Year Fellowships. Today we would do that with a word processor, but in 1961 this was the only game in town.
By 1964 Orange Coast College had an IBM 1401 and an IBM 1620 as tools in their instruction program and the LGP-30 had been relegrated to the intro classes. Unfortunately the paper tape reader was not always accurate hence many students developed the habit of blaming the reader rather than their program for failure. The LGP-30 was then given to the Tech Division. A IBM 1620 simulator program known as CYBERNAC was written and used to demonstrate the features of a computer in the Intro classes.
Someone in the Tech Division forgot the first rule of the LGP-30 --namely if you turn it off you have to waite 45 minutes before you turn it on. In doing this they scored the drum and with no money to fix it, the LGP-30 dropped out of sight.
{Pictured above left to right are the papertape reader/punch, the flexowriter, and the LGP-30 computer makeing up the computer system at OCC in 1960.}
================ From the Programming Class Notes ======================
LGP-30 PHYSICAL DESCRIPTION
The LGP-30 is commonly referred to as a desk computer. Obviously, this phrase originated because the size of the LGP-30 closely parallels the size of a standard office desk. The LGP-30 is 26" deep, 33" high, and 44" long, exclusive of the typewriter shelf. The computer weighs approximately 800 pounds and is mounted on sturdy casters which facilitates movement of the computer.
Another asset in regard to the computer's mobility is its power requirement. The LGP-30 requires 1500 watts when operating under full load. The power inlet cord may be plugged into any standard 115 volt 60 cycle single phase line. The computer contains 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 contains the circuitry required to permit a warm-up stage. This warm-up stage minimizes 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 needs to be installed ,if the room is kept within a reasonable temperature range.
The computer contains 113 electronic tubes and 1450 diodes. The 113 electronic tubes are mounted on 34 etched circuit pluggable cards which also contain associated components. Although 34 pluggable cards are used, there are only 12 different types of such cards. Card-extenders are available to permit dynamic testing of all machine functions. Six hundred and eighty of the 1450 diodes are mounted on one pluggable logic board. This logic board may be quickly removed and is very accessible for service personnels use.
The main memory consists of a magnetic drum that contains 4096 words. An instruction or data word may be stored in each one of the 4096 available words. When instructions are placed on the drum, they will be executed in sequence until one of the instructions "transfers control" to a new set of instructions.
============================================================================
The LGP-30 could do a GILL calcualtion in 36.0 milliseconds. It rented for $1,100 and sold for $39,600 in 1957. Seven units were produced in 1956. The first installiation was in Sept 1956 in Pasadena, CA.
The LGP-30 had 16 instructions
OP-CODE SYMBOL FUNCTION OP-CODE SYMBOL FUNCTION 0000 Z STOP 1000 P PRINT 0001 B BRING 1001 E EXTRACT 0010 Y STORE ADDRESS 1010 U UNC-TRANSFER 0011 R RETURN ADDRESS 1011 T TEST 0100 I INPUT 1100 H HOLD 0101 D DIVIDE 1101 C CLEAR 0110 N MULTIPLY 1110 A ADD 0111 M MULTIPLY 1111 S SUBTRACT
The LGP-30 had a "Psudo" 32 bit accumulator which was stored on the drum memory. Actually it had 32 such accumulators on one track of the drum and in the multiplication functions a 64 bit product was stored. The 'M' or 0111 multiply would give you the first 32 bits of the product while the 'N' or 0110 multiply would work the last 32 bits.
All calculations were in pure binary. Real values were faked as integer and the programmer had to take care of the bit point or the 'Q' for each value.
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.}
Location Counter Last Instruction executed Accumulator
Since this writer has been trained on an IBM 650, the LGP-30 was not very impressive. However the flexowriter was an impressive unit. With it you could cut a paper tape as you filled out a form, and then use that tape to fill out similar forms. In Fall 61 this writer used the system to complete several four page applications for National Science Foundation Academic Year Fellowships. Today we would do that with a word processor, but in 1961 this was the only game in town.
By 1964 Orange Coast College had an IBM 1401 and an IBM 1620 as tools in their instruction program and the LGP-30 had been relegrated to the intro classes. Unfortunately the paper tape reader was not always accurate hence many students developed the habit of blaming the reader rather than their program for failure. The LGP-30 was then given to the Tech Division. A IBM 1620 simulator program known as CYBERNAC was written and used to demonstrate the features of a computer in the Intro classes.
Someone in the Tech Division forgot the first rule of the LGP-30 --namely if you turn it off you have to waite 45 minutes before you turn it on. In doing this they scored the drum and with no money to fix it, the LGP-30 dropped out of sight.