[no subject]

IRQ for the 6502 is a level.  There is no acknowledgement.  If the
IRQ level stays low, then another IRQ will occur as soon as IRQ is
re-enabled.  Most hardware that generates an IRQ stops asserting
it when status is read, which is the responsibility of the IRQ handler,
which is, of course, running disabled.

The flashing cursor prior to the //e is generated by substituting a
"flashing" character in the character set, which is toggled between
"true" and "inverse" representation by an asynchronous signal
generated by a 555 timer.