5 Nov
2007
5 Nov
'07
7:10 a.m.
From: cclist at sydex.com> > On 4 Nov 2007 at
22:41, Atsushi Takahashi wrote:> > > Old PCs and in fact new PCs often drop
characters when doing Hex Dumps,> > for example. The faster the CPU, the fewer
dropped characters,> > obviously... I see the value of using dedicated terminal
hardware.> > Certainly true if you're using an 8250 UART chip. Replacing it with
> a 16550 and making sure that your software enables the FIFO can help > quite a
bit.> > And there were/are high-performance serial cards with large buffers. >
Names escape me at the moment, but they were popular with some BBS > sysops.> >
One thing that used to hurt a lot with old PCs and graphics cards was > the way that
software implemented scrolling--by performing block > moves on the display buffer
contents. Write your own screen handling > software to manage the same thing by
changing the starting display > address instead if the display adapter that you're
using doesn't have > a scrolling feature.> > Really, there's no reason
that a PC should lag behind a 1980's > terminal that used a lowly 4MHz Z80.>
> Cheers,> Chuck> Hi
I've only had problems of dropping when running a
direct serial
DOS program while in a windows DOS window.
I'm told one can tell windows that that particular serial port
doesn't exist but I'm not sure that solves the problem.
I've run at 115.2 transfers in DOS without dropping a single
character, with a 286 processor.
There are a few things. Do not have a disk buffer program
running. These can take the computers time at any time
it feels it needs to read/write the disk. Keep things simple.
Scrolling the screen is a tough one. Instead of letting the
BIOS do the scrolling, do it your self a line at a time. Between
lines, check for characters in the serial's buffer. Have a reasonable
RAM buffer to hold these until you finish scrolling.
Doing it this way, one should be able to be fine.
Dwight
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