> > > Simple answer. The control store functionality had to fit in the available > space > on one hex > sized card, and 16K density DRAM was the only option. Allocating additional > space to use > 4K or 1K SRAM would have pushed the CPU design to an additional board, which > was not > a design option at the time.
The 11/730 was released in 1982 (according to Wikipedia which I don't take a gospel, but I have no other source of information for this). The PERQ 1a was certainly out by then, it had a control store using 16K*1 SRAM chips. OK 20 pin as against 16 pin packages, but I don't think the 11/730 boards are that tighly packed (anyway, using SRAM would probably have eliminated some support devices like address multiplexers). -tony
