By 1988, industry observers stated that the NES's popularity had grown so quickly that the market for Nintendo cartridges was larger than that for all home computer software. Compute! reported in 1989 that Nintendo had sold seven million NES systems in 1988, almost as many as the number of Commodore 64s sold in its first five years. "Computer game makers [are] scared stiff", the magazine said, stating that Nintendo's popularity caused most competitors to have poor sales during the previous Christmas and resulted in serious financial problems for some.
The 7 million sold almost equated to which console's six year span?