[Coco] Drivewire question

[Darren A]

On 3/25/09, Steven Hirsch wrote:
>
> I have some doubts about the 6551 being capable of 115.2k baud.  Even if
> the chip itself can do it, the expansion bus may prove to be a bottleneck.
>
---

What do you mean by "expansion bus"?  Are you talking about the
cartridge port and/or MultiPak?

There would certainly be no bottleneck there since data can traverse
the bus at a rate of at least 1 byte every cycle.  For 115.2k baud,
the CPU only needs to service the 6551 roughly once every 77 cycles
(not including any status polling).  The double density floppy
controllers have to transfer data at more than twice that speed (250
kbps).

Darren