Correction to 'Directory-based cache coherence in large-scale multiprocessor'

A corrected version of fig. 4 of the above-titled paper (see ibid., vol.23, no.6, p.49-58, 1990) is provided. Because two shades of black appeared to be continuous when printed, the speech bar chart in the figure did not properly illustrate the difference between the 'Read only processing by block' and the 'Unoptimized trace' portions of the bars. >