Every aspect of the 1950s computer environment was dramatically different than anything we see today. Not just the size. In 1957 I was a Customers Engineer on the IBM 704, 705 and 709 at Lockheed Burbank and JPL Pasadena. Lockheed had two 704s and one 705 in the same room. These were supported by 9 computer operators 12 technicians and a couple of senior guys who were available for consultation on tough problems. We worked three 8 hour rotating shifts for 24 hour coverage. The computers were rented for $350 an hour.
Each computer had a card reader, a card punch and a printer that was a modified 407 EDPM machine. These peripherals were big oily things that required lots of preventive maintenance. Then there were the tape drives. Each drive was almost the size of a phone booth. The reels fed tape into vacuum columns. The tape was moved over the R/W head with prolay units, solenoid operated spinning wheels that could start and stop the tape in milliseconds. All of this generated dust from the oxide on the tape that had to be constantly removed.
The 704 was a 32 bit accumulator (31+ sign) binary system. Accumulator operations were parallel. It had a 32 bit adder. The system at JPL had extended precision. A second accumulator (larger than a fridge) was attached to the main frame for 64 bit parallel data. If I remember correctly, it had a 13.5 microsecond add time.
The 705 was a variable word length BCD machine. The A-F codes were used for beginning of word, end of word, decimal point etc.. It was an easy system to program.
These systems required stable power. So, the feed from the power company was attached to a motor generator with a big flywheel. To turn the system on from a cold start you pushed the button on the contactor and waited for the motor generator to run up and stabilize. Then you turned on the computer power supply. This started the power up sequence. The first thing up was the VT filament voltages. These were arrayed in a balanced bridge so if a filament was out you got a loud ding and the system shut down. Then you could apply filament voltage only and look for dark filaments. When the filaments were good you could restart the power up sequence which took about 15 minutes if all was well.
Support personnel had a work area for scopes and equipment and parts. I think we had 4 long work benches. Also part of the uniform in addition to the 3 piece suit, white shirt and tie was a tool kit housed in a leather brief case with your name in gold.
A dropped bit would be an operator problem. The operator had a listing of each program. A dropped bit would stop execution with a parity error and the contents of all registers would be displayed on the control panel. The operator would read the program listing to find the missing bit, replace it and figure out the best way to continue execution.
Running the computer was a hands on activity. You watched and listened to all of the components. There were lots of visual and audio clues to potential problems. A tape drive would reread a word if it got a read check. That made a sound like a pop. Standing in the middle of the computer floor you could hear the read checks as pop pop pop here and there. The sounds would lead you to the drives with weak tubes and you could change them on the fly. Most systems had 8 to 12 drives on line. The address of the drive was determined by the operator using a dial on the drive door. The operator would take a drive off line with the number switch. We had to do frequent visual checks to see which drives were actually on line and do quick fixes.
Running those computers was a lot like what I imagine driving a horse drawn wagon to be. There would always be 3 or more people assisting when the system was running. There was always the issue of using non-IBM cards and tapes. The consent decree forbade us from telling the customer that his programs wouldn’t load or run because he was using Crosby tape or cheap cards. We could adjust the card reader and punch to accept the cheap cards but we would get more card jams. A card jam in a punch that is running payroll checks is a nightmare. You have to recover every piece of every card and put them back together.
With tape it was a confrontation with the customer. He said he was getting read errors. I could only say the tape drives are working properly. The cure was that he had to run diagnostics on his tape reels. That could take hours of computer time that he paid for if the tapes did not pass. In the case I am thinking of, after 12 hours of testing the customer returned the Crosby tapes and went back to IBM.
There is really no comparison between those systems and todays computers. IBM was service and reliability. We described our products as “cut the speed in half, double the price, paint it grey and put IBM on the side”.