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COMMUNICATION |
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CPC - KDS COMMUNICATOR
104
The KDS Communicator
104 is a modem from KDS Electronics. Unlike most other modems, it connects
directly to the CPC's expansion port (rather than using a separate serial
RS232 interface).
Note: KDS also
made a different modem, the Mini-Max Modem, which has a different front-plate,
and which connects to the CPC via separate RS232 interface.
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CPC - KDS SERIAL
INTERFACE
A RS232 interface
by KDS Electronics.
All of them were
wired incorrectly. d7 was d0, d6 was d1, and so on. Consequently you had
to reverse the bit order before you could do anything useful with it.
In addition,
the hardware handshaking didn't work properly, and since the ports were
different to those used by the Amstrad/Pace interface, you were limited
to the built-in KDS software. Which sucked.
Connects to expansion
port. Contains software in ROM bank 6. Has one single 25pin DSUB connector
(with TX,RX,RTS,CTS). The baudrates are generated by the 8253, and can
be further divided by the 6850 (DIV1,16,64). (for example 6850=DIV1, and
8253 Counter=01A1h gives 4800 baud; 2MHz/01A1h/1).
KDS has wired
the 6850 chip's data bus incorrectly: D7 is D0, D6 is D1, etc. (so the
bit order must be reversed by software). And, reportedly, the hardware
handshaking doesn't work properly (no idea if that's a hardware or software
glitch, or maybe the 6850's 1-stage RXFIFO is just too small for high baudrates?).
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CPC - MINI-MAX
MODEM 1200
A 1200 baud modem
sold by UK peripherals firm KDS Electronics.
The following
description was found on an eBay listing:
"This is an Original
Extremely rare 1200 bps modem for the Amstrad CPC series of computers.
The package consists of a KDS Electronics Serial Interface (which also
contains the KDS Comm 5 software in ROM), once plugged into the expansion
bus of the Amstrad the ROM is immediatly recognised and starts up the Comms
software for the Modem from the integrated ROM. A lead is supplied to comnnect
the actual Modem to the ROM Interface.
"The Modem comes
with a built in mains connection lead and standard telephone lead, Once
plugged into the mains and connected to the interface and a telephone connection
the modem is ready for use, all software is built into the interface no
discs or tapes are required (or supplied).
"The modem is
a full duplex modem with settings for ANS, CCITT,ORIG, 1200-75 75-1200
ORIG, Bell and ANS. Red LEDs on the front display TX (transmission) RX
(receive) Carrier and power. The software can be used with the presets
already contained on ROM or user defined settings ( a basic knowledge of
comms will be useful here) and includes a telephone book for you to store
and use telephone numbers.
"The interface
is provided with a through connector to allow you to plug in other expansion
devices at the same time (i.e. DD1 disk drive, digitiser, EPROM writer)
It certainly works fine with the DD1 connected and i have had a ROMBO VIDI
connected at the same time without any problems.
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CPC SCHNEIDER
- BTX MODULE 1987
Schneider Btx-Modul
für CPC 464/664/6128. Based on a universal Btx-Decoder from Siemens.
The device is connected to expansion port, and additionally connected between
computer and monitor.
Unknown if the
device includes the actual modem built-in... probably, one needed to rent
the BTX modem from Deutsche Bundespost separately.
Type: PC/HC-Decoder
Country: Germany
OEM: Siemens
Year: 1987
Connectors: D-BT
03, RGB for Monitor or colorprinter
Protocol: CEPT
ID Numbers: P07747,
Siemens S30817-K732-A101-1 / A30817-X732-A100-1, Schneider Ident Nr. 36445
or 36486
See also: http://btxmuseum.de/Hardware/
(german)
BTX (Bildschirmtext,
translated as Screentext) has been a german service, allowing to transfer
data via telephone line. In the 8bit era, the Deutsche Bundespost (german
postal service) still owned the monopoly for telecommunications in germany,
so the only (legal) way to transmit electronic data via telephone line
has been to use their BTX service.
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CPC SCHNEIDER
- SERIAL INTERFACE RS232
RS232 Interface
for the CPC by Schneider. Schneider is the german distributor for Amstrad
CPC hardware (however, this interface seems to be Schneider's own invention,
not an Amstrad product).
The original Schneider
RS232 Interface was released around 1985. Two years later, in 1987, a software-compatible
clone was released as DIY schematic in a german book (link). Even later,
around 1996, a copy of that DIY schematic also circulated in the internet
(link). The DIY port address, timings and handshake signals are exactly
the same as in the original Schneider version - except that DCD (Data Carrier
Detect) isn't implemented in the DIY version.
The uncommon shape
of the housing dates back to a Schneider BTX modul (which was being intended
to be plugged into Schneider Television Sets). Apparently Schneider produced
too many housings, and re-used them for the RS232 interface. Actually,
a RS232 interface is very much the same as a BTX interface (the actual
BTX modem must be rented separately from Deutsche Bundespost), so even
the PCB may be (almost/exactly?) the same for both devices.
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