TNC1.1
The hardware modification is now complete.  It is now
necessary to prepare the EPROMs.  Comparing the pin-out of the 2764
to that of the 27128 reveals only one difference: pin 26 is not
connected on the 2764, and is the high-order address line (A13) on
the 27128.  If any of your EPROMs are the same for both versions of
the firmware, or are unused (the firmware I am using resides in
only two EPROMs), they may be used without change.  For each EPROM
which must be bank selected follow these steps. 

Locate the two 2764's which share one chip location (for
example, U9 or $8000.  Copy firmware version "A" into a 27128
starting at location $0000.  Copy firmware version "B" into the
same 27128 at location $2000.  Repeat the above steps for U10
($A000), U11 ($C000) and U12 ($E000).  Be careful not to mix
addresses in the chip -- in other words, if you load version "A" at
$0000 in one EPROM, make sure that all of version "A" is burned
into the low half of the EPROM.
CONTINUED IN FILE TNC1.12