HARDWAREPERIPHERIQUES CPC - MODEMS ★ The KDS104 Modem reviewed|Amstrad Computer User) ★

Modem - KDS Communicator 104Hardware Peripheriques Cpc - Modems
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It is frequently amazing the way prices of computers and peripherals drop. The higher the electronic content, the greater the decrease. Disc drives and printers are mechanical, so these will never drop in price in the way that computers and calculators have. A modem is very much an electronic device. As a result a simple acoustic modem which would have cost over £350 three years ago can now be picked up for under £50. More advanced modems boast features which the early micro users would never have dreamed of. These multi-standard modems are becoming increasingly popular. The first Amstrad dedicated modem is now available from KDS.


The KDS104 comes in a very smart box. Early models, like the one pictured here, are black, later ones will be grey. The front panel has none of the usual knobs and switches associated with a versatile modem; all the setting up is handled by software. Instead there are two eight segment LEDs which tell you what is going on at any given time.

The box is very light since the power supply is built into the plug. This connects to the only socket on the back of the modem. The 'phone wire is permanently connected, as is the ribbon cable, to the computer's expansion port. The telephone lead has one of the new style connectors but since the modem is not approved it is illegal to connect it to the public telephone system without using a 'buffer box'. The through connector on the disc port works perfectly and allows you to add speech synths, light pens, a disc interface and whatever else you wish to hook up.
Inside, the KDS 104 is not nearly as neat. The single-sided printed circuit board (PCB) has a very cheap feel to it and does not follow the convention of pointing all the chips in the same direction. The chip to drive the LED display has its pins bent up to make the connection. The board is well spaced and remained cool throughout the test. There is not much to building a modem these days thanks to the AMD7910 modem-on a chip. This does all the hard work and is the main reason that the price of modems has dropped in recent months. There are various components to decode the signals from the Amstrad port and an Eprom containing the communications software. It is nice to see third party manufacturers using ROM based software to drive peripherals. This after all is the main reason that Amstrad included sideways ROMs in the design of the CPC464. All things considered I was impressed by the function of the hardware, if not by it's construction.


The KDS modem is packaged in a smart grey and white box. Having spent a lot of money on this, KDS have skimped on the production of the documentation. I hope that the stapled sheets of paper are a stop-gap but nowhere did the documentation claim to be provisional. The whole thing looks as though it has been produced on a DMP-1. This printer may be adequate for listings but not for explaining how to use a fairly complicated peripheral. The whole manual has been written in capital letters making it hard to read the nine page document.

The actual content, however, is fairly good, although the lack of diagrams is painfully obvious. There is a good amount of forward referencing which means you really have to sit down and read the whole manual before attempting to do anything. It would be much better to be shown how to do individual jobs, such as logging into Prestel, or using BT Gold. Even splitting the sub-headings onto seperate pages would help. The tables of available settings do not really explain what you need to type in; a list of the commonly used settings would be helpful. Fortunately, the software can be used as a menu-driven system so a fairly experienced user can cope without the manual. A list of free databases would have been a good idea; there are plenty of them.


It is the software which can make or break a product like this and, with several direct rivals, notably the Amstrad RS232C interface reviewed last month, the KDS programs only just scrape through. Terminal software is very personal, each user has different habits and will want to use the modem for different things. Flexibility and ease of use do not go hand-in-hand. KDS have tried very hard to provide a well-rounded system and have gone some way to succeeding. The I menu command gives a full list of the available RSXes and the |MODEM command sends you through a set of menus to get you on-line. This is all a novice user will need to know to get on-line.

Both the on-screen prompts and the appropriate RSX have the word 'receive' missing the second 'E', the manual gets it right. This is not only a bit sloppy but could mean that software compatible with early versions of the software will not work with later versions, where, I hope, it will be corrected.


It is only since the advent of the microcomputer that Prestel has proved popular. It was originally conceived as a system to link televisions and the telephone. It is only now that the six year old project has started to make money. When Prestel was devised, British Telecom got together with the television companies who were working on teletext (Ceefax and Oracle) to make the two systems as compatible as possible. The result is a complex system of codes to define graphics and colours, these were looked at in detail in last month's "Amstrad User", suffice it to say that the codes allow a picture with eight colours, limited graphics and some special facilities such as flashing and double height text to be transmitted as IK of information. This builds a screen 40 columns wide by 25 lines deep. To make this work, a character mapped screen is required. The Amstrad's screen is bit mapped, this allows a much better graphical resolution but means that the 40 column mode only allows for four colours.

The Amstrad RS232C interface compensates for this by using clever software in the twenty column mode. KDS have taken the same route as the Protek modem reviewed in the May issue and used the 40 column mode with only four colours. This means that the display is readable but it does not show you what the author on Prestel expected you to see. Flashing text is shown steady and some of the dynamic frames turn out very garbled. The majority of frames are garbled, it is hard to tell if this is a hardware fault or a bug in the software but, by using another system connected to the same 'phone line, you can see that it is due to the modem misinterpreting valid data.The most annoying limitation of the Prestel software is the lack of a cursor on the mailbox pages. If you just want to log in, read the news and log off again then the prestel terminal is fine, if you are interested in editing and sending information look elsewhere.

Other databases

Most public databases can be accessed with the KDS 104. The Post Office's Packet Switching System (PSS) links to databases around the world, many Universities and to British Telecom Gold Electronic mail. There are local numbers nearly everywhere, so if you want to log into the American 'Compuserve' database you need only pay for a local call. Most of the really big databases expect you to have an eighty column display, since there is no way to change the mode through the I modem menu, you will need to set up everything manually using an RSX. A simple Basic program will do the job and you can use this to go through all the logging-in for you, sending your own passwords. I played MUD using the KDS 104 and everything seemed to work OK, other people at 'Amstrad User' have logged into privately run Bulletin boards and have even written a Bulletin board to run on the CPC464 using the Auto-answer mode.


The KDS 104 is a desirable unit. It may not be as finished as I would have liked and there are still some rough edges. Amstrad Technical are amazed that the modem works with such a length of ribbon cable. If you are fussy then I would advise you to wait a few months until the software has settled down and production quantities justify a better internal design. I doubt that the modem will ever get approval since the process requires a huge amount of red tape and would have to extend to the software. My modem did not come with a little red triangle sticker but then it was an early (production) model. In terms of value for money it is excellent, its nearest rival is something like the Amstrad RS232C interface and a standard modem such as a Minor Miracles WS2000 or Pace Nightingale. This set-up would cost a similar amount, be better made and BT approved. It would also be less flexible and not offer such a friendly display to the user. As ever you pay your money and you take your choice.

Amstrad User November 85

★ YEAR: 1985
★ PRICE: £350


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L'Amstrad CPC est une machine 8 bits à base d'un Z80 à 4MHz. Le premier de la gamme fut le CPC 464 en 1984, équipé d'un lecteur de cassettes intégré il se plaçait en concurrent  du Commodore C64 beaucoup plus compliqué à utiliser et plus cher. Ce fut un réel succès et sorti cette même années le CPC 664 équipé d'un lecteur de disquettes trois pouces intégré. Sa vie fut de courte durée puisqu'en 1985 il fut remplacé par le CPC 6128 qui était plus compact, plus soigné et surtout qui avait 128Ko de RAM au lieu de 64Ko.