[zxspectrum] Re: idea folle di un ignorante
- From: Malantrucco Carlo <carlo.malantrucco@xxxxxxxxx>
- To: zxspectrum@xxxxxxxxxxxxx
- Date: Wed, 19 Nov 2014 01:31:01 +0100
Il giorno 19/nov/2014, alle ore 00.40, Luca Alimandi ha scritto:
> Se non ricordo male, T stava per Text e B stava per Byte, cioè codifica a 7
> bit e a 8 bit...
> In un caso serviva a mandare semplici codici ASCII che poi la stampante
> interpretava e stampava con le proprie impostazioni, nel secondo serviva ad
> inviare anche i caratteri di controllo (escape) per impostare NLQ, grassetto,
> italico, ecc...
> Ma non sono proprio sicuro...
Direi che ti ricordi bene, il manuale dell'Opus Discovery recita così riguardo
la porta parallela:
The ' 'b'' channel sends and receives characters without changing them in any
way.
The "t" channel does make changes to the characters. For output, BASIC tokens
are expanded and graphics characters are printed as '?' (see the reference
section for details). For input characters have their most significant bit set
to zero. The "t" channel is used as a text channel, while the "b" channel is
used as a binary channel.
"b"- input and output to the parallel port, characters are sent and received as
8 bits with no translation.
"t" - input and output to the parallel port. For input the top bit is set to
zero giving codes between 0 and 127. For output character codes less than 32
are ignored (except for CR which causes a CR or a CL/LF pair to be sent, see
below). Character codes greater than 127 are expanded if they represent BASIC
tokens and are printed as '?' if they represent graphics characters. The full
specification is"t";<status> .
Carlo
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