IBM Series 1 User Manual page 61

The figure shows two arbitrary delays in series with
the return tags. These delays are fed by the logical "OR"
of the respective gate tag and data strobe, called the
envelope of the outbound tag.
The
two envelopes can
be
conveniently used internally in the attachment for such
purposes as gating data out to the interface and tor gating
data strobe. The delay should allow for appropriate data
and condition code activation and deactivation on the
interface in the correct relationships with the return tag.
The figure also illustrates deselection and degating of
return tags with any of the three synchronous channel
directed resets. Note that device reset (which is a DPC
command) is not included in these resets, since its action
is different. This will be explained further in the
discussion of the poll mechanism which follows.
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