🚀 go-pugleaf

To add to John Hutchinson's recommendations for getting the most out
of a Mega 4ST..

Probably the best upgrade would be the TEC board from CodeHead (in the US).
They have a model which just plugs into the Mega bus connector and is
extremely easy to install.  TOS 2.06 eliminates the need for most of the
AUTO folder patches, speeds up disk access and increases the functionality
of the desktop tremendously.
 
The expansion connector has a few things available for it, but the choices
are very limited (Moniterm monitor card, math coprocessor, umm..?). The
best use of it is for the TEC card, in my opinion.

A disk cache will speed up reads from the hard drive, but only really if
your applications hit the disk a lot.  Things like compilation, database
lookups, anything that reads the same sectors a lot.  Using one with
applications that just load and run, and maybe save a document occasionally
won't really gain much from the cache.  On the other hand, with 4 Megs
available, there's not much reason not to run one.

Also, one of the nice things about the Mega is that the SST board from
Gadgets will fit..!

BobR