jcallen@maxzilla.encore.com (Jerry Callen) (12/28/90)
I'm still trying to figure out memory for the floppy controller. SRAM is so easy, and we could have 256K (2 128Kx8 parts) for about $50. On the other hand, with DRAM we could have 512K (4 256Kx4 parts) for $25. I think I can handle plain old read/write access. It's the $#@ refresh requirement that keeps hosing me. Would people totally barf if the controller did refresh via software? One of the three timers on the 'CG160 could be programmed to pop every 8ms, and the interrupt routine could use MOVS to touch all 512 rows. At 16MHz this would cost about 10% of the available memory bandwidth. Yes, it's ugly as sin, but it WOULD give us a lot more memory for a lot less cash. DMA would still run at full speed (4 megabytes/second). -- Jerry "master of the kludge" Callen jcallen@encore.com