[sebhc] H8/H17 emulator available to prelim. trials

Dave Dunfield dave04a at dunfield.com
Mon May 24 19:12:22 CDT 2004

>The "SPACE" feature used underruns and framing errors to determine what the
>next baud rate to try was.  I don't know how you would emulate this.  Bit 6
>of I/O port 362Q (from the XCON card) allowed the baud rate to be set to
>9600 by default.  Emulating the XCON card might be easier if you haven't.

As the console serial port gets it data from the PC keyboard buffer, it will
bever get a framing error - underruns do not occur on a async port, however
the virtual uart will not see framing errors or parity errors either ---

however --- I would assume that if the first baud rate tried results in a
SPACE character with no errors, then the driver would assume it has it righ.

Also, the standard H5 serial card can only do two baudrates under software control,
x16 (9600) and x64 (2400) - depending on the baud rate clock jumper settings -
so there would only be two possible settings to try (the x1 setting is invalid
unless you have a clock synced to the data) - since there is no speed associated
with the PC keyboard/video display, my driver ignores this control bit - so
every single attempt by the H8 side driver to obtain an error free "SPACE" should
be successful - no matter what it has the baud rate programmed to...

I'll have to dig into it more at some point.

Btw, I forgot to mention in my original post, the H17 emulation currently supports
only 40 track, 10 sectors single density, single sided - the disk image file should
be exactly 102400 bytes in size, and is simply a raw binary dump of the disk data
sectors only - additional formats may come "later".


dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Vintage computing equipment collector.

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