# Tag Info

Accepted

### What is smallest addressable value in an octal number called?

No matter what base system you use it is called a digit. So if it is not clear from the context and you need/want to emphasize that it is a digit of a number in base 8 representation then call it ...
• 16.4k
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### Why is a register initialised through bitwise operations instead of a binary string?

0b00001000 vs 1<<3 The binary notation is not standards-compliant C. That might just rule it out. If it doesn't rule it ...
• 97.6k
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### What is the process of going from machine code to electrically controlling individual transistors?

Ah, you're missing the STATE MACHINE concept. That's where we can "write code" made out of TTL hardware chips: data-selectors, 4-bit counters, gangs of parallel flipflops. (But all those are the ...
• 11k

### Memory capability and powers of 2

Memory addresses are binary numbers. The range of an N-bit (unsigned) binary number is 0 to 2N-1, a total of 2N different values. Since addresses are passed to memory chips as binary numbers, it ...
• 176k
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### check if an unsigned binary number is divisible by 15

Do you know how to check for divisibility by 9 in base 10? Add all the digits using base 10 arithmetic. If the result has multiple digits, repeat the process. Stop when you have one digit. If the ...
• 170k
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### Why is the Gray code called a cyclic code?

cyclic ˈsʌɪklɪk,ˈsɪklɪk/ adjective 1. occurring in cycles; regularly repeated. You haven't given a reference for the 'cyclic code' terminology but there is certainly a cyclic patter. This is most ...
• 178k
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### How to deal with signed int overflows

Clearing up some misunderstandings will probably help. First, your data is a 16-bit value. There's no "overflows" and "actual data" -- the 16 bits are just divided into two 8-bit pieces (bytes). To ...
• 22.2k

### Why is the Gray code called a cyclic code?

Take the four bit Gray code sequence below and print it out then cut it out with scissors. Then wrap the ends round and tape them together so you have a Gray-code band. As you rotate the band notice ...
• 46.9k
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### Memory capability and powers of 2

A 1024 x 1 memory chip requires 10 address lines and you get full utilisation of all addresses. Now, if someone brought out a 600 x 1 memory chip, it would still need 10 address lines. It can’t use 9 ...
• 465k

### Why is a register initialised through bitwise operations instead of a binary string?

Well, the example is very poor, as for initializating the whole port after reset, either one can be used. The point is that later on, you might want to control one bit only, and keep the state of the ...
• 161k
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### How do we control a 7-segment display with a rotary switch to ground and 12v supply?

There’s a less complicated way to do this. Since you only have six positions you could use a diode matrix. Each segment is connected to the switch through diodes so that in position 1 the cathodes for ...
• 25.6k

### ISA opcodes---Where do they come from?

If you group similar instructions together, patterns will emerge. This is very obvious in ARM, where the ISA manual actually shows you which bit of an instruction word correspond to function, register ...
• 46.9k

### Why is the Gray code called a cyclic code?

The Gray code for decimal 15 rolls over to decimal 0 with only one switch change. This is called the "cyclic" property of a Gray code. Straight from the Wikipedia article.
• 466

### What is the process of going from machine code to electrically controlling individual transistors?

A processor is really a finite state machine (FSM) for implementing the machine code instructions. It reads the instructions from memory and uses the required hardware, such as the ALU, to implement ...
• 6,167

### Is it possible to set starting count on binary counters like CD4020?

You could use a binary adder on the 4020 output lines. Then use the output of the adder instead of the direct output. You'd need something like a bunch of DIP switches to set the offset (that gets ...
• 465k

### Why is a register initialised through bitwise operations instead of a binary string?

I don't know about the shifting, but the ORing is most useful is when the same register shares multiple unrelated functions. Then the second initialization doesn't disturb the previous initialization. ...
• 16.5k
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### Decimal conversion of a 32-bit hexadecimal number

First convert it to binary: 0001 1011 0000 1000 1100 0010 0010 1011 Then map it to its fields: ...
• 78.4k
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### ISA opcodes---Where do they come from?

In a lot of cases, the choice is pretty arbitrary or based on "wherever it fits best" as ISAs grow over time. However, the MOS 6502 is a wonderful example of a chip where the ISA design was heavily ...
• 306
Accepted

### A confusion regarding signed representation of binary numbers

In 2's complement, 1000 does not represent 0, but rather -8. So, in your ADC (or DAC), you would use it to represent -4.0 V. More precisely, in an ADC, each code ...
• 176k
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### How to multiply fixed point numbers of different format

This isn't particularly different from multiplying two fixed point numbers with the same format. You need to do a multiplication which preserves the most significant bits, then shift the binary point ...
• 46.9k
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### Xilinx bit file different between builds

There is an option to randomize the build process, which IIRC is enabled by default. As FPGA layout is an optimization problem with high complexity, it is not possible to find the globally optimal ...
• 12.7k

### ISA opcodes---Where do they come from?

Someone at some point sat down and defined them. A good ISA will make the decoder as simple as possible. For example with an ALU instruction you could let some bits of the opcode be sent directly ...
• 2,843
Accepted

### Why does a full adder need an OR gate?

You're making a couple of assumptions: Multiple outputs can be connected directly together When any such output is "high", then the wire is "high". This is known as "wired-OR", and indeed, such ...
• 176k

### Multiplying signed to unsigned binary numbers in verilog

The width of your expression is very important when dealing with signed arithmetic. To multiply two 6-bit numbers and get a result of -63, you need at least 7 bits. You also need ...
• 8,665

### VHDL: difference between using "+" or writing our own adder

Both have their uses: The second gives potentially better hardware in a real-life scenario, the first can be given to students as coursework for a course named "history of hardware" or something ...
• 1,077
Accepted

### Transmitting binary data from scratch via radio (wireless)

The component that you're looking for is called a Voltage Controlled Oscillator, or VCO. It's an electronic oscillator whose frequency is controlled by an external voltage signal. You can either build ...
• 20.1k
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### Is 2's complement the only way that singed binary numbers are represented?

We all float on again...right back into the land of sign-magnitude numbers! Twos' complement is almost universally used for integer arithmetic for the exact reasons you stated -- addition and ...
• 8,988