Random Access Memory Cell
Computers need to store and retrieve data from memory. Random Access Memory (RAM) provides a number of memory loations that data can be read from or written to.
The circuit shows 4 memory locations of 3 bits each. The RAM is controlled from register Z. Bits 1 and 2 hold the address. Bits 4, 5 and 6 hold the data to be written into memory, or the data retrieved from memory. Bit 3 is set to 0 to read, or 1 to write.
Operation
Only points in the Z register are operable. Set them to read data from, or write data to specific memory locations.
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| Click layout to pause/run train | Click points to switch 0/1 | Click start circle to reset train/points |
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Lazy points switch between upper 0 or lower 1 branch lines Trains arriving on a branch line switch the point to that line |
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Sprung points allow branch line trains to join the main line All main line trains go straight ahead and never 'branch off' |
Note
- The read/write points are bypassed so that they are not switched by the train on its return journey.