NEC PC 8201A Accessory?

From: Jeff Kaneko <jeff.kaneko_at_ifrsys.com>
Date: Thu Jun 19 19:35:49 1997

Marvin:

What you have there is a break-out box for AMPS cellular telephones.
You put the box between the phones handset and tranceiver unit,
and you can tap into the audio circuits of the phone.

In the early days of cellular radio, any phone that was listed as
"AMPS complete" could be used with the handset of any other phone
likewise listed. This was done to give third-party equipment
supliers the opportunity to make custom accessories that would work
with a variety of phones.

The 1985 seems to confirm that this was used for testing these "AMPS
complete" cellular phones (they were about all that was available
then). The computer probly had some test software on it, to send
commands to the tranceiver.

BTW, interfaces like this were also used with cellphones as system
diagnostic tools for cellular networks, to analyze coverage areas and
call quality. The amps complete phone is almost non-existent today.
Most (if not all) now use a proprietary communication scheme between
the handset and tranceiver. Most phones for sale today, as you know,
don't even have this connection; the tranceiver and handset are all
one unit.

The true "AMPS Complete" phone is a bit of a classic in of itself!

Jeff

P.S. =

Mod = Modulator
RSSI = Receiver Signal Strength Indicator
NRZ = Non-return to Zero data used by the phone for control.
Bit Clock = Recovered clock for the above datastream



> Date: Wed, 18 Jun 1997 01:54:17 -0500 (CDT)
> Reply-to: classiccmp_at_u.washington.edu
> From: Brett <danjo_at_xnet.com>
> To: "Discussion re-collecting of classic computers" <classiccmp_at_u.washington.edu>
> Subject: Re: NEC PC 8201A Accessory?
> X-To: Discussion re-collecting of classic computers <classiccmp_at_u.washington.edu>

>
> On Tue, 17 Jun 1997, Marvin wrote:
> > I have another strange device. This one is called a Channel Tester,
> > Ser. No. 55263, and a date of 1985-4. It has a series of BNC connectors
> > on the face labeled "Tx Audio", "RX Audio", "Spk", "Voice Tx Test",
> > "Voice Rx Test", "Mod", "Disc", "RSSI", "NRZ Data", and "Bit CLock". I
> > got it attached to an NEC PC 8201A (as I recall) TRS-80 Model 100
> > clone. It also has a male and female Centronix interface plugs on the
> > side away from where it attaches to the 8201A. Does anyone have any
> > idea what this thing is? Thanks!
>
> Are they 50 pin Centronics? If they are, it could be a telephone tester.
> The Centronics port (at 50 pins) would take a "whip" and let you test
> all the lines on a PBX or straight telephone cable.
>
> If they are 36 pin Centronics I really don't know what used NRZ encoding
> in the early 80's except tape drives - or maybe its a tester for a radio
> land line from studio to tramsmitter - it does have the Mod-ulation BNC
> connection.
>
> Other than that - I'm stumped 8-) Who made it - NEC?
>
> BC
>
>
Received on Thu Jun 19 1997 - 19:35:49 BST