29 Feb
2020
29 Feb
'20
3:23 a.m.
On Fri, 28 Feb 2020, Adam Thornton wrote:
A RocketPort multi-serial sounds really, really likely
for an
astrophysics data collection instrument. Thank you! Mystery probably
solved!
I remember the RocketPort; we used to call it the OctopusPort...
The 8250 was unbuffered or maybe had a 1 byte buffer,
the 16450 had a
1-byte buffer, the 16550 had a 16-byte buffer. I remember vividly how
much better my life got when I got 16550 serial ports for my '386.
The 16550 series was an utter balls-up, with broken silos etc. This is
from http://en.wikipedia.org/wiki/16550_UART :
The original 16550 had a bug that prevented this FIFO from being used.
National Semiconductor later released the 16550A which corrected this
issue. Not all manufacturers adopted this nomenclature, however,
continuing to refer to the fixed chip as a 16550.
According to another source, the FIFO issue was corrected only in the
16550AF model, with the A model still being buggy. (The C and CF
models are okay too, according to this source.) The 16550AFN model
added DMA transfers.
You had to pay careful attention to the manufacturer and the suffix.
-- Dave