11 Mar
2017
11 Mar
'17
5:10 p.m.
I'm not sure about the MicroVax II but on some
other VAX and Alpha
machines, the console port may be less capable than ordinary terminal
ports in the way of buffering, flow control, 8 bit support and so on.
The KA630, the MicroVAX-II CPU board (which includes the console serial
port), has a relatively limited serial port. For example, it has only
a byte or two of buffering in each direction, it cannot be used
directly from userland even if the kernel wants to let it (it is
accessed with MFPR and MTPR instructions), it has no software baudrate
control, and various other limitations.
These have concomitant benefits for console use, such as no software
setup being required to get small numbers of characters transferred.
But they do rather cripple it for voluminous data transfer. If you
have an at-least-mildly-smart serial port card (eg, with substantial
hardware buffering capability, and/or with DMA capability), you will
probably get better performance with it.
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