[comp.sys.next] mixing 4MB and 1MB simms

u-sgreen%peruvian.utah.edu@cs.utah.edu (Scott Greenman) (08/07/90)

Can you put both 4MB and 1MB simms in a NeXT?  We are considering buying
some 4MB simms for a NeXT that now has 8 1MB simms.  Will we be able to keep
the 1MB simms in and add 4MB simms?

Scott Greenman
Univ of Utah
College of Nursing

phd_ivo@gsbacd.uchicago.edu (08/07/90)

In article <1990Aug6.161543.27832@hellgate.utah.edu>, u-sgreen%peruvian.utah.edu@cs.utah.edu (Scott Greenman) writes...
 
>Can you put both 4MB and 1MB simms in a NeXT?

In particular, can I buy 1 or 2 4MB SIMMs, or do they have to be bought
in pairs of 4? I.e., Can I use 8 1MB SIMMs and 2 4MB SIMMs?

/ivo welch	ivo@next.agsm.ucla.edu

u-sgreen%peruvian.utah.edu@cs.utah.edu (Scott Greenman) (08/08/90)

Recently, I asked the following questions:

=>Can you put both 4MB and 1MB simms in a NeXT?  We are considering buying
=>some 4MB simms for a NeXT that now has 8 1MB simms.  Will we be able to keep
=>the 1MB simms in and add 4MB simms?

Here is a summary of the answers I received:

The SIMMS in the next are arranged in banks of 4, with 4 banks or 16 SIMMS
total.  Each bank must have all the same type (1MB/4MB) SIMMS.  You can have
both banks of 1MB SIMMS and banks of 4MB SIMMS, but you can't mix them within
a bank.  I believe that you must have four SIMMS in each bank, i.e. no
partially filled banks, though I'm not positive on this.

Thanks to all those that responded to my question.

Scott Greenman
Univ of Utah
College of Nursing

hess@iuvax.cs.indiana.edu (Caleb Hess) (08/08/90)

In article <1990Aug7.170347.8696@hellgate.utah.edu> u-sgreen%peruvian.utah.edu@cs.utah.edu (Scott Greenman) writes:
>I believe that you must have four SIMMS in each bank, i.e. no
>partially filled banks, though I'm not positive on this.

Each SIMM is 8 bits wide.  Four SIMM's are required to make a 32-bit wide
word, to match the 68030's data path.

rca@tahoe.cs.brown.edu (Ronald C.F. Antony) (08/09/90)

|>In particular, can I buy 1 or 2 4MB SIMMs, or do they have to be bought
|>in pairs of 4? I.e., Can I use 8 1MB SIMMs and 2 4MB SIMMs?

Most probably you will have to buy them in increments of 4, as the NeXT has
32-bit memory and the SIMMs are organized 4Mbit*8bit. So you need 4 of them
to get to a 4Mbit*32bit organisation.

Ronald
        
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