Chuck McManis <cmcmanis(a)mcmanis.com> wrote: Which is why no one with any sense put 12 normal serial ports on a PC. Instead there was a thriving business in multiport cards from companies like Digi. Which isn't really dissimilar to the situation on minicomputers. In principle, you *could* put a whole bunch of DL11 async ports on a PDP-11. But noone in their right mind did so. Instead, they used DH11 and DZ11 muxes. So this is just another red herring in the attempt to prop up the assertion that old VAXen are "better" than late 1980s PCs. Actually, almost all PCs now *do* have the equivalent of a channel for the disk. It's not as functional as a 360/370 channel, but it's roughly comparable to the Massbus and DSI interfaces used on VAXen. It's split between the bus-mastering ATA interfaces of the Intel and Via chipsets, and the local intelligence of the disk drive. And almost all high-end Ethernet and SCSI cards have functionality equivalent to a channel. The 486DX2/66 systems Mike C. was comparing to obviously didn't have the PCI bus-mastering ATA disk interface. But for server applications those systems were typically configured with an Adaptec 1542 SCSI controller, which served as a very intelligent channel processor. Yes, I've been involved with businesses that used 486-class machines to server as many as 64 terminals for point of sale and inventory applications. No, there was no way that the system would have had adequate performance if it had to support that many users doing serious software development. But then, neither could the VAX. The 8650 which I used in the mid 80s would serve 50 users easily as long as only a few people were doing memory and CPU intensive things. But if more than three or four people tried to do a compile at once, performance went to hell. Which would have been OK if only the compute-bound jobs suffered. But the scheduler couldn't cope will enough, so even the "light" jobs became unresponsive. This is because everything that was learned in the 1960s and 1970s about building good timesharing systems was subsequently forgotten in the early 1980s.

Chuck McManis <cmcmanis(a)mcmanis.com> wrote: Hi The problem with dropping characters was because of slow video in scrolling the screen. I rewrote a scroll that did one line at a time and then checked the UART. It was able to handle text at 115.2K without any UART buffering at all. It did have a software fifo for the input though. So, it can be done, you just have to know the bottle neck. Dwight