External data bus/ Internal Data bus

Hello everyone. I'm a bit confused, I was wondering if anyone could help clarify something for me. I'm reading a chapter out of "Mike Meyers Certification Passport A+", and its in a chapter about system resources. Here is an exact quote of what the paragraph says:

"Previous chapters explained that the CPU uses the external data bus to transfer lines of program between memory (RAM and ROM) and the CPU. The external data bus also enables data to travel back and forth from peripherals, such as the keyboard, hard drives, and CD-ROM drives, to the CPU"

Now, a different resource told me that the INTERNAL data bus is what handles communication between things like CPU and memory. These two different resources seem to be conflicting, could anyone clarify?

Find more posts tagged with

SAVE $250 on Your Boot Camp — Use Code "EXAM26"

Exclusively for TechExams members for Infosec Boot Camps starting before April 30, 2026

View Boot Camps

Comments

cheeblie

The internal data bus is the bus that handles communications between the CPU and the cache on the CPU, which is like memory.

Cheeblie

axis_D

just the cache? but not the RAM or ROM?

cheeblie

No, that's the job of the external data bus.

Cheeblie

axis_D

Now this article, seems to be saying that the internal bus handles all communication within the "case", and external handles peripherals, I might be missing something, or not getting it..but is this article wrong?

http://www.pccomputernotes.com/system_bus/bus01.htm

cheeblie

I have a book that states the that only the CPU is involved in the internal data bus.

There are two separate data buses. The internal data bus lets the CPU communicate with the various circuits and internal caches of memory that are incorporated as part of the chip's design. Typically, this bus is extremely fast and is independent of the rest of the computer. The external data bus communicates with the rest of the computer.

Since it is a published resource, as is your A+ book, I would trust it over any website article. Also, I'm fairly confident that it is correct.

Cheeblie

axis_D

ok..thanks I appreciate the help, and clarification.

cheeblie

By the way, that was from the Exam Cram of Server+ written by Deborah and Jeff Haralson. I thought it was a very good read and it covered SCSI very well. But you don't have to take my word for it.
::Reading Rainbow Music Plays::

Cheeblie

axis_D

lol. I used to watch that everry day.

Webmaster

I'm not an expert on this, but I agree with Cheeblie... (not with his note about website articles however... a new published book contains at least as much errors as any collection of web articles.. usually even more..., but books have errata

)... The word external refers to external to the CPU...

RidiculousOne

Pardon my confusion, but is the "internal data bus" connected to the L1 cache...as in the 80486, or is it what was once called the "backside bus" that linked the CPU and L2 cache—as in Pentium Pro and Pentium II?

To be honest, I rarely see the term "internal data bus" used anymore.