9 Jun
2014
9 Jun
'14
12:51 p.m.
The SIO was
expensive in comparison to the other commodity UARTs.
Even when you add the cost of the additional suppport, such as a BRG?
The 6402 was more expensive than NMOS UARTs. I would have thought that the
only reason to use it would have been if single supply operation (not
available on the early NMOS parts) or low power dissipation were needed,
and neither was an issue for the Quay.
You maty fidnm the -12V rail is connected to the UART footprint on the
PCB.
Quite often the UART that was actually fitted was the oen that was
cheapest at the time of producation of that run of boards. After all,
they all work the same way.
Thos dumb UARTs ahve one advantage over things liek the Z80-SIO for
console terminal ports and that is that all the parameters can be
triivally set by lings/swithes wired to pins on the UART. That's one less
thing for the monitor ROM to o. It also means you can configure the prot
as you want it and know itreally is set that way.
-tony