HP3000-L Archives

November 1995, Week 4

HP3000-L@RAVEN.UTC.EDU
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Subject:
Re: Flow Control on HP3000 with MPE V
From:
"R. Van Valkenburgh" <[log in to unmask]>
Reply To:
R. Van Valkenburgh
Date:
Fri, 24 Nov 1995 04:08:40 GMT
Content-Type:
text/plain
Parts/Attachments:
text/plain (16 lines) 
Ah yes, ENQ-ACK.  The way this worked is that the terminal driver issued
an "ENQ" character (0x05 or ctrl E) each time it was ready to send a
block of characters (I think usually about 80, if it had that many).  The
terminal was expected to respond with an "ACK" (0x06 or ctrl F) if it was
ready to receive.
 
If the ACK was not received after a timeout period, the driver would
eventually send a block anyway.  This is why, when using an MPE/V
termtype 10 port with on non-HP (non-acking) terminal, the screen is slow
to display.  One can work around this problem by pressing the ctrl and F
key to send the ACK char.
 
(Brings back the old days...)
 
Regards,

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