Stored Program Computers and Computer Memories: Part 1 Flashcards
Before stored program computers
Machines received instructions from tape or punched cards; Hard wired connections
John Von Neumann (1903 - 1957)
A renowned genius;
Credited with the invention of SPC’s
Von Neumann and the EDVAC
Participated in discussions on the design(instructions stored on tape); Wrote the first report on the EDVAC
Thermal memory
Used temperature changes to store and retrieve information. It was unreliable
Mechanical memory
Z1 sliding plates, relays, disk-pin. However, it was much slower than electronics
Mercury delay line
Binary number represented using pulses; Difficult to get good contact b/w mercury and quartz
Acoustic delay line
Inexpensive, theoretically possible; Prone to interference
Slinky delay line
Current passes through the slinky; Slinky would oscillate too much
Magnetostrictive delay line
Wave would go through the wire towards a magnet that would amplify the pulse. Less temperature sensitive than Mercury delay line
Delay Line Drawbacks
Delay;
Information stored in the delay mechanism was only available after a delay
Electrostatic memory
First high speed random access memory (Form of vacuum storage)
Read around problem
Leaving a bit on for too long would corrupt its surrounding bits
Selectron
Wafers consisting of states opened by currents; Costly
Rotating magnetic memories
Impractical for real use (slow access time)
Two level memory
Magnetic drum(slow, high capacity) and Williams tube(fast, low capacity)
Booth’s magnetic memory disk
Developed floppy disk based memory, and then magnetic drum memory which was used in the ABC
Static Magnetic Core Memories
Detection wire to detect if both horizontal and vertical wire were magnetized
Core Memory significance
Speed increased by a multiple;
Maintenance time drastically decreased
Core Memory advantages
cores can be small;
non-volatile;
Random access
