Analog modem emulator?

[Vintage Computer Festival]

On Wed, 10 Aug 2005, Tony Duell wrote:

> > > Sounds like the cards were approximately contemporary.
> >
> > That's perfectly reasonable.  It could be that the Serial card was meant
> > for local interfacing to serial peripherals while the Communications card
> > was meant for "high-speed" telecommunications applications.
>
> Yes. The bit-banger is fairly usless for serial input, although it's fine
> for output. I suspect it was mainly used for driving a serial printer (I
> first came across it with a Qume Sprint 5 hooked up to it), and Apple
> used ETX/ACK protocol _because_ you then know when the peripheral is
> possibly going to send something (unlike XON/XOFF when the peripheral
> could send said characters at any time).

Ok, here's what each manual says (note the publication dates):

Communications Interface Card Installation and Operating Manual (10/78)

These are the fundamental abilities of the APPLE Communications Interface,
using the nearly universal RS232 standard:

1. Input for the APPLE II can be taken from an external device, instead of
from the APPLE's keyboard.

2. Output from the APPLE II can be sent to an external device, to the
APPLE's TV screen, or to both.

3. The APPLE II can be used as a terminal, in full-duplex mode or
half-duplex mode, at 300 baud or 110 baud[*].  It can be put into (and
taken out of) terminal modem, either from the APPLE keyboard or from the
external device.

4. The BREAK signal can be sent from the keyboard.

[*] My note: There are instructions in the back for modifying the card for
1200/300 baud operation or 4800/1200 baud operation.


Serial Interface Card Installation and Operating Manual (3/79)

These are the fundamental abilities of the APPLE Serial Interface, using
the nearly universal RS232 standard:

1. Output from the APPLE II can be sent to a serial printer or other
external serial device, to the APPLE's TV screen, or to both.  The Serial
Interface can supply the necessary line-feeds with carriage returns, etc.

2. Input for the APPLE II can be taken either from an external device or
from the APPLE's keyboard, or from both simultaneously.

3. The APPLE II can handle half-duplex communications at rates from 75 to
19,200 baud, in both directions, with ap rinter, another APPLE,. a
terminal, modem or other RS232 external device.

4. The Serial Interface can also be connected for current-loop operation
with a Teletype.

-- 

Sellam Ismail                                        Vintage Computer Festival
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International Man of Intrigue and Danger                http://www.vintage.org

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