On 2016-01-01 22:16, J. David Bryan wrote:
On Friday, January 1, 2016 at 22:02, Johnny Billquist wrote:
Um. What does 7B and 7P stand for here?
From the "Writing a Simulator for the SIMH System" manual:
SIMH provides routines to convert ASCII input characters to the
format expected VM, and to convert VM-supplied ASCII characters to
C-standard format. [...] The supported modes are:
TTUF_MODE_8B: 8b mode; no conversion.
TTUF_MODE_7B: 7b mode; the high-order bit is masked off.
TTUF_MODE_7P: 7b printable mode; the high-order bit is masked off.
In addition, on output, if the character is not printable, -1 is
returned.
TTUF_MODE_UC: 7b upper case mode; the high-order bit is masked off.
In addition, lower case is converted to upper case. If the character
is not printable, -1 is returned.
The set of printable control characters is contained in the global
bit-vector variable sim_tt_pchar. Each bit represents the character
corresponding to the bit number (e.g., bit 0 represents NUL, bit 1
represents SOH, etc.). If a bit is set, the corresponding control
character is considered printable. It initially contains the following
characters: BEL, BS, HT, LF, and CR.
So "7B" designates the set of 7-bit characters, and "7P" designates the set
of 7-bit characters considered printable.
Aha. Thanks.
And if you are using anything that manage to print something visible
when outputting a NUL, that sounds like something broken somewhere
else.
Tell it to Microsoft. ;-) Putting a Windows console window into "raw"
mode, as the simulator does when it's running, prints control characters as
graphic symbols. That interferes with programs running under simulation
that expect echoed control characters to be non-printing.
I'd say that such a "terminal" should not be used then. A basic
requirement that it supports ASCII should be reasonable. That thing
obviously do not do ASCII. I don't mind there being support for such a
broken thing, but why have it as default. If someone use such a broken
then, then they should adjust things to whatever brokenness is in their
environment. But no need to break things for people who actually have
proper equipment.
Johnny
-- Dave
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--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: b...@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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