Date   : Sun, 28 Nov 2010 17:55:19 +0000
From   : jgh@... (J.G.Harston)
Subject: remote access via serial link

Mark Usher wrote:
> What I would like to be able to do is to have guaranteed access to the
> Master via the serial port from switch on. Would need the ability for Escape
> and Break functionality also. In short, serial remote access without
> graphics capability. Above all it needs to be robust.

*LinkOn at http://mdfs.net/Spectrum/Tools remains links through Break,
but you need to get to the keyboard first.

Otherwise, a version in ROM, or even HostFS which I've been bashing
away at all weekend at http://mdfs.net/tube/Serial.

The simplest ROM sould be something like:
.Serv1
TYA:PHA
LDA #2:LDX #1:JSR OSBYTE :\ Input from Serial
LDA #3:LDX #1:JSR OSBYTE :\ Output to Serial
LDA #181:LDX #0:LDY#0:JSR OSBYTE :\ Serial input expands Escapes and FKeys
PLA:TAY:LDX &F4:LDA #1:RTS

By Break functionality, do you mean you want to be able to
remotely cause a Reset? Not possible over the serial port,
there's no way to cause a Reset from software.

Yes, people will start shouting CALL !-4, but that's not
causing a Reset, that's jumping to the Reset code. The
Reset code assumes the hardware has been reset by a physical
hardware reset and you get problems if it hasn't.

In the past I toyed with the idea of connecting the cassette
motor rely to the Reset line, so then *MOTOR 1 would cause
a Reset.

-- 
J.G.Harston - jgh@...