federico@actisb.uucp (Federico Heinz) (05/04/90)
I have noticed some very strange behaviour using the RS232 port of the
Z88. When you receive data through the port at a baud rate higher
than 2400 baud (that is, 9600 and up, since the Z88 doesn't support
4800 baud), the port sort of "locks up". I can consistently reproduce
it by logging in our Unix system with the vt52 emulator, and doing,
say, a 'cat' of an ASCII file. The first few lines (or characters, it
is not consistent) arrive OK, but after that it starts to look like
line noise, and the thing eventually stops receiving anything. The
only way out is <>KILLing the vt52 process, then start again. The
same problems arise when using the Import/Export facility to get data
into the machine. There are no glitches transmitting data at any
speed. At first I thought it might be a matter of XON/XOFF (which was
ON), but I spied into the data with a line monitor, and the host
behaved correctly.
One REAL weird thing about it is that I tried sending data from my
computer at home (an Atari Mega ST) to the Z88 using a terminal
emulation program (Uniterm, if you know what I'm talking about) at
19200 baud, and it worked like a charm. When I used a program of my
own to do the same, (that doesn't do anything strange, the RS232 is a
file as far as it can tell), the problem showed up again. I have
tried to receive data at 9600+ baud from different machines, mostly
Unix boxes, with multiple cable lengths and such, but it won't go
away. Is this something that happens with every Z88 out there, or is
something wrong with mine? I figure whether the port supports 9600
baud and up only on a character basis, but the machine cannot handle
the throughput, thus needing for a pause between individual characters
to give the software a chance to pick them up before an overrun
happens. This would (sort of) explain why it works with some
software, and not with some other.
--
Federico Heinz
"'?Y zi mejod la pateo?" --- Guille
From Europe: ...!mcvax!unido!tub!actisb!federico
From elsewhere: ...!uunet!pyramid!/malis@bbn.com (Andy Malis) (05/05/90)
federico@actisb.uucp (Federico Heinz) writes: >I have noticed some very strange behaviour using the RS232 port of the >Z88. When you receive data through the port at a baud rate higher >than 2400 baud (that is, 9600 and up, since the Z88 doesn't support >4800 baud), the port sort of "locks up". Using my Mac (in Versaterm), I sent some good-sized files down to the Z88 (running VT52) at 9600 and 19,200 with no problems at all. I did have XON-XOFF enabled at both ends. Andy Malis <malis@bbn.com> UUCP: {harvard,rutgers,uunet}!bbn!malis