In all previous Macintosh models that have RAM SIMM slots, there were
configuration requirements that dictated the following:
- All SIMM boards within a bank must be the same density.
- Within a bank that contains RAM, all four slots in that bank must be
filled.
- All SIMM boards must be installed in Bank A for configurations that
fill only one bank.
- Higher density SIMM boards must be installed in Bank A for
configurations that have different densities in each bank.
In the IIci, the first two restrictions still apply. However, the second
two are not requirements for IIci RAM configurations. These restrictions
have been eliminated, due to functionality provided by the Memory Decode
Unit (MDU).
Following are the valid RAM configurations supported by the Macintosh
IIci:
(SPECIAL NOTE: Some of the RAM configuration recommendations that are
made below will be in direct opposition to configuration requirements on
all previous modular Macintosh models.)
- 1MB: Four 256KB SIMMs can be installed in either bank. However, the
built-in video feature requires that the RAM be installed in Bank A. If
the memory is installed in Bank B, built-in video will be disabled, but
the IIci will work fine.
- 2MB: Four 256KB SIMMs are installed in each bank.
- 4MB: Four 1MB SIMMs can be installed in either bank. However, the
built-in video feature requires that the RAM be installed in Bank A. If
the memory is installed in Bank B, built-in video will be disabled, but
the IIci will work fine.
- 5MB: There are two possible 5MB configurations. The preferred is to
install four 256KB SIMMs in Bank A, and four 1MB SIMMs in Bank B. This
configuration is preferred because it minimizes the effects of video
cycle stealing. The second is to install the 1MB SIMMs in Bank A and
the 256KB SIMMs in Bank B.
- 8MB: Four 1MB SIMMs are installed in each bank.
4MB SIMM modules when available, can be used in the IIci. All of the
above recommendations and requirements will still apply.