PSB No: S-0086A
Page: 2 of 8
Q4.
What is page interleave memory architecture?
A.
Page/interleave memory architecture is a method for increasing memory
access time. Memory that is interleaved provides faster retrieval during
sequential memory access. Interleaved architecture requires at least two
banks of memory. Even memory addresses are in the first bank, odd
memory in the second. While the processor is accessing memory in the first
bank, memory in the second bank is being prepared for immediate access.
In order to utilize the interleaving capabilities of the Equity 386/20, at least
2MB of memory are required when using 256K SIMMs, and 8MB when using
1 MB SIMMs.
Page mode divides the memory into blocks called pages. When working
within any page, memory access is fast. Access speed is slightly diminished
when pages are switched, after which memory is again accessed at
maximum speed.
Combining these two methods provides a greater “hit ratio”, that is, a greater
percentage of memory that is accessed at 0 wait states. Not accessing within
a page or not sequentially results in 2-3 wait states. however, since this does
not happen very often, overall performance of the system memory is
generally less than 1 wait state.
Q5.
How many wait states does the Equity 386/20 have?
A.
The wait states on the Equity 386/20 depend on the hit ratio: 0 wait states on
a hit and 2-3 wait states on a miss. With its page/interleave memory
architecture, the Equity 386/20 provides fast memory access at a lower cost
than other memory architectures.
Q6.
What are the EMS software capabilities of the Equity
386/20?
A.
The Epson EMS software supports LIM 4.0 standards. It provides expanded
memory capability for such applications as Lotus 123, Reflex, Autocad and
Framework II. EMS allows an application to have more memory available for
data storage. The application itself must reside in the 640k RAM accessible
by MS-DOS, but it can use expanded memory capabilities to build larger
spreadsheets, databases, etc.
Before the 80386 microprocessor existed, computer systems required special
hardware to support expanded memory. With EMS software, 80386
machines can emulate expanded memory through the addition of memory
chips; extra hardware or a special board are not required.
