[simh] RSTS processor identification

[Eric Smith]

On Fri, Mar 5, 2021 at 6:33 PM Paul Koning via cctalk <cctalk at classiccmp.org>
wrote:

> I would have liked better comms.  The USART has such a tiny FIFO that you
> can't run it at higher than 9600 bps even with the J-11 CPU.  At least not
> with RSTS; perhaps a lighter weight OS can do better.  The printer port is
> worse, that one can't run DDCMP reliably at more than 4800 bps.  I normally
> run DDCMP on the PC3XC, which is a 4-line serial card that uses two dual
> UART chips (2681?) with reasonable FIFO.
>

There seem to be a great many models of Unibus and Qbus multi-port async
serial boards, which present different register-level interfaces, e.g. for
Unibus, DH11, DHU11, DJ11, DM11, DZ11 . Which ones are considered "best",
for each bus, for use with a multitasking OS like RSTS/E or RSX-11M+?