# 8 bit & 4 bit transistor register

• posted
1)An 8 bit transistor register has output voltage of LHLHLHLH,What is equivalent decimal number being stored? (2) A 4 bit transistor registry has output voltage of HLHL,what binary number and it's decimal equivalent is stored?

I am new in ems cos want to qualify test for entry.

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• posted

i have posted same in Com.Arch group,here is one answer,which one I believe?

Eric Smith Jun 9, 10:30 pm show options

Newsgroups: comp.arch From: Eric Smith - Find messages by this author Date: 09 Jun 2005 19:30:02 -0700

"Thaqala> (1)An 8 bit transistor register has output voltage of LHLHLHLH,What is

If the machine is using negative logic with excess-3 BCD arithmetic, it's storing 77 decimal or 22 decimal, depending on which end is the MSB. Unless it's a signed tens-comlement number, in which case it is 23 decimal.

• posted

Yikes. more poorly constructed questions.

Binary logic can code a 1 as either a more positive (H) or more negative (L) level. It is strictly a matter of convention. But a logic high is more commonly used to represent a value of 1 than a logic low is, so lets go with that convention.

Then there is a convention, not a hard rule whether the left most bit represents the smaller or higher binary value. Based on the conventions for decimal numbers let's assume that the right most bit represents the smallest power of 2.

Bit there are still lots of ways that bits might represent value. There are positive only values, sign and value, 2's compliment codes,

1's complement and then there are many ways to represent a floating point value. There is also a decimal code commonly used called binary coded decimal or BCD that uses each group of 4 binary bits to represent a decimal digit. But let's guess that they are asking about the simplest code for integer positive values.

Under those assumptions, LHLHLHLH would be the binary 01010101 and would represent the binary value of

2^6 + 2^4 + 2^2 + 2^0 or 64 + 16 + 4 + 1 = 85 decimal.

Using these same assumptions for the 4 bit register holding HLHL, the pattern would represent the binary number, 1010 which would represent a value of

2^3 + 2^1 = 8 + 2 = 10 decimal.

This result rules out the possibility that this code is BCD, since 9 is the highest value used for a digit.

Have these examples made it clear how these conversions work (based on the assumed but not stated conventions)?

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They are messing with you.

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55 hex or 85 decimal

1010 binary or 10 decimal

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I suspect this is done on purpose...perhaps to cause the unsure to second guess themselves. I did give the engineers answer to a Ph.D. uncle of mine when he asked if the glass was half full or half empty...that being that the container is twice the required volume. He had to think on that one!

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You are given no encoding scheme such as positive or negative logic or what the column values represent, all of which John touch upon. The answer given above is on the outer fringe.

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That's correct if it's given in msb-lsb order. (bit 7 through bit 0). I've seen documentation starting with bit 0. Moreover, low voltage meaning 1 is not unheard of...

If either one of these is true, the number is 170. Of course, if both are true, you're back to 85 again. Figuring out why is an excercise the

OP seems to need...

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The glass is completely full - half with water and half with air.

What does that make me? ;-)

Cheers! Rich

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Cross posted to SED.

The proper answer is.

'How much is left in the bottle?'

Obviously, for non-engineers, this will lead to a discussion about the relative levels of liquid left in the bottle.

However the engineer will consider factors such as,

'Have I got another one?' 'Is the shop still open?' 'Will this be enough?' 'Do I have the means required to aquire another one?' 'Perhaps I'll just go to bed.'

DNA

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A realist? :-)

Tom

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Those are good questions...

Another quip to doctor relatives is that there is a 'vas deferens' between children and no children.

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Gotta remember that one... :-)

Tom

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Tom

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-------------------------- If L is 0 and H is 1, and lsb is last, then: LHLHLHLH is 010101 which is 85 = 0 + 64 + 0 + 16 + 0 + 4 + 0 + 1 HLHL is 1010 which is 10 = 8 + 0 + 2 + 0

-Steve

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• posted

Umm, an amphibian? ;-)

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