Hi Brian, the 2^1000 was copied from the article I posted the link to.
I'm not sure what the ^ caret is suppose to represent it is not what I
would usually consider to the 'Power' of. Binary math is the answer as
to why 1000=1024 beyond that was an I don't care. As to your question on
I believe Extended Memory Service aka EMS memory. EMS memory was The
16 bit microprocessor could only address a binary one megabyte. I'm not
sure if it was IBM that devised the memory map or Microsoft. The memory
map divides 1 meg into sections the first that we know as
motherboard/system memory 640k. The additional 384k was divided up on
the 8bit BUS. I don't remember all the sections, but there was 128k
section to which memory could be paged in and out. This Memory map was
used by the IBM AT also which was a true 16 bit computer with a 16 bit
BUS, but 80286 had a Lobotomy problem. This all went away with the Intel
80386, 32 bit microprocessor, and I forget the memory limit, and could
switch between 'Real' and 'Protected' without a reboot. From 80386 IBM
AT computer on is today’s computer are some some additional BUSs . The
only limit to memory is the processor and motherboard
manufacture/designer. To say that the microprocessor directly addresses
the memory is a misnomer. The is a Direct Memory Access (DMA) chip that
does the routine of addressing memory. Some motherboard diagnostics
would check the DMA chips on the MB.
On 04/09/2016 04:49 AM, Brian Gray via olympus wrote:
Hi
The PC Helpdesk got it right but 2 raised to the power 1000 is not
equal to 1000, it is way bigger! 1024 is equal to 2 raised to the power
10. A schooldays memory is of a story about an ancient king who agreed
to pay another king, as a penalty, 1 grain of corn on the first square
of a chess board, 2 grains on the second, 4 on the third, 8 on the
fourth etc up to the 64 chess board squares. He could not fulfil his
agreement because there is not that much corn in the world! This all
relates to why we have SD, SDHC and SDXC memory cards because there is
a limit to the number of memory locations which can be addressed
unaided by a 64 bit system.
One of the computer gurus on the list can no doubt explain how High
Capacity and Extended Capacity cards get around this limitation.
Brian Gray
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