Tektronix Terminal Emulation

Warner Losh imp at bsdimp.com
Sat Mar 11 22:50:27 CST 2017

On Sat, Mar 11, 2017 at 6:10 PM, Mouse via cctalk <cctalk at classiccmp.org> wrote:
>> 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.

It was 8-bit clean. And did allow for connection of a printer to it,
though a relatively simple one. We wound up in the end, though, not
using it except in a pinch. The limitations were just a bit too much
to give reliable behavior for anything other than having a DECwriter
II or VT220 connected to it.

We had a 4-port serial card to connect the plotter, and a few other
specialty devices we needed for our VaxStation II (which had the same
KA630 CPU board and a graphics board).


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