Benchmark Wars (was Re: gauging interest in VAX 6000-530)

At 04:01 PM 10/24/99 -0700, Mike wrote: [snip] Ok, you've considered the memory bandwidth without considering: 1) That disk transfers also happen across this bus. 2) Other I/O (mouse? Sound? Video?) 3) The interrupt load on the CPU. As an empirical note the 16450 UART often could not be serviced fast enough by the 486DX66 to prevent it from dropping incoming characters above 9600 baud. That was even with the "FastCOM" driver that came with Procomm plus for DOS, not until the 16550 added a 16 (or was it 32) character FIFO did it work. Now multiply that by 12? Say 9600 baud, every types a key. That is 12 interrupts to service while you're potentially trying to push out 12 streams of bytes. Anyway, the VAX (and most DEC gear) got around this by having channel processors _everywhere_ and of course the modern PC has channel processors _nowhere_. (IDE taking this to the logical extreme) Somewhere I've got an 8 port serial card that was built for the 16 bit ISA bus (it has 8 mini-din connectors on the card edge). The thought was to run UNIX on a 486 and use terminals for multiple students. It didn't work. The PC couldn't keep up. I fully admit though that given source code I might have been able to make it work :-) --Chuck