CONFIG_ISA is not available for the selected architecture x86.
Result is shown for architecture m68k

CONFIG_ISA (not configurable)

configname: CONFIG_ISA

Linux Kernel Configuration
└─>ISA
In linux kernel since version 2.6.12 )
Find out whether you have ISA slots on your motherboard. ISA is the
name of a bus system, i.e. the way the CPU talks to the other stuff
inside your box. Other bus systems are PCI, EISA, MicroChannel
(MCA) or VESA. ISA is an older system, now being displaced by PCI;
newer boards don't support it. If you have ISA, say Y, otherwise N.