Can you please explain about increment/decrement latch in 8085. I am currently studying registers and encountered this in the array of register section.

Here are the things i found when i googled and need some explanations

The 8-bit contents of a register or a memory location can be incremented or decremented by 1.

This 16-bit register is used to increment or decrement the content of program counter and stack pointer register by 1.

Increment or decrement can be performed on any register or a memory location.

Q1.How are the above mentioned operations done by it please explain that.

Also Please explain this:

enter image description here

Q2. The term Address Latch in the above context is also confusing me so it be great relief i someone explains that to me.

Q3. In the block diagram increment/decrement latch is connected to the address and data buffer why is it so?


  • \$\begingroup\$ There's really no way to answer this unless you give us some idea of what you already understand about computers in general, and about the 8085 specifically. \$\endgroup\$ – Dave Tweed Apr 21 '18 at 14:39
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    \$\begingroup\$ What's the question? \$\endgroup\$ – Chu Apr 21 '18 at 18:13
  • \$\begingroup\$ I know fair amount of digital electronics and i am starting to learn microprocessor and encountered this while learning registers \$\endgroup\$ – rimalonfire Apr 22 '18 at 2:28
  • \$\begingroup\$ Where did you find this excerpt? \$\endgroup\$ – Dave Tweed Apr 23 '18 at 11:49
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    \$\begingroup\$ @SamGibson: I suspected as much. Thanks for putting a lot more effort into this than I ever would have! \$\endgroup\$ – Dave Tweed Apr 23 '18 at 16:19

That last sentence ("An increment/decrement register ...") is indeed confusing.

First of all, it should have started a new paragraph, because it really has nothing to do with the rest of the paragraph to which it is attached.

Second, increment/decrement is a function block, not a register. You can feed the contents of any of the 16-bit register pairs through this logic in order to modify the value.

Regarding the rest of the paragraph, as it says, the address latch is an internal implementation detail, used to hold an address from any of the 16-bit registers in order to maintain bus timing while other internal operations are going on. It is not a user-accessible architectural feature.


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