Computer Solutions Ltd
 Advanced Search

After supplying all your  Embedded Development Tool needs for 42 years
 Computer Solutions Ltd and its web shop are now closed.



 Having reached the grand old age of 75 it is time to relax and fulfil other ambitions.

 Its been an exciting ride with you, our customers, often on the bleeding edge of technology
 and I thank you for your friendship, your trust, and your orders.

Stay well        I wish you all success in your future projects.

Chris Stephens.



     But what to do with the web site ?  It has taken >12 man years of work to create a repository of knowledge on many aspects of the art and science of embedded microprocessor development and even after closing the shop it still gets over 4,000 visitors per month.  So as a service to my customers I have decide to keep it live providing my technical insights on the products and then redirecting viewers to sites where they can purchase the items they used to buy from us. Follow the link   "Home"

       The  "Information zone"  consists of articles produced as background tutorials on subjects of interest to those designing new products.  As different CPUs have became available this has lead to new development techniques and in particular to new ways of communicating between nodes.


Home Information Zone


RT-IP FULL TCP/IP Network Stack

CMX TCP/IP is the only TCP/IP solution you need for Embedded applications. It's embedded in set top boxes to connect thousands of homes to the internet through their cable TV provider. It connects instruments to a PC or workstation over Ethernet. It links industrial controllers on LAN's to host computers. RT-IP is sophisticated enough to handle the toughest wide area networking job but is still compact and economical enough to be used in simple LAN applications. RT-IP's low cost, clean implementation and high functionality make it a breeze to add TCP/IP networking to any application.


  • Excellent TCP implementation

  • Standard sockets API

  • Proprietary Extensions API

  • Built in DNS support

  • Thorough Regression Test

  • No-copy option for both UDP and TCP

  • Supports IP fragments

  • Supports 68000, PowerPC, 80X86, SH, ARM, MIPS, 51-XA, Coldfire etc

  • Standard IBM-PC DOS port supplied as demo

  • Supports CMX, smx, RtKernel, AMX, Nucleus, RTPX, RTXC, pSOS, TNT, ETS, TNTRT, Pharlap, µCOS

  • Supports polled mode (no kernel)

  • Easy to port to new kernels

  • SLIP/CSLIP and Ethernet support included

  • & these common features of EBS software

TCP/IP layers

Confused?- Consult our plain mans guide to TCP mnemonics.

RT-IP Stack

TFTP Server & Client     SMB  
FTP Server & Client     SNMP V1 + V2  
NFS Server & Client     SNMP V3  
Telnet Server     DHCP Server  
Telnet Client & Server     DHCP Client  
Web Server     POP3  
SMB     SMTP   
Secure Socket Layer    
Internet Key Exchange     PPP  
IGMP     PPPoE  
802.11b wireless Ethernet
Autonomous IP Generation     IMAP  
SNTP     Router  

Porting RT/IP

Our real-time OS porting layer is short and sweet, only one header file and one small 'C' file need modification to port the library to a new kernel. We currently support the following kernels: CMX, smx, RtKernel, AMX, Nucleus, RTPX, RTXC, pSOS, TNT, ETS, TNTRT, Pharlap. Call for information on the latest supported kernels. Our free multi tasking nucleus RT-PX runs in polled mode for those installations not requiring a real time kernel.

Driver Support

We support the following Ethernet boards:

Western Digital/SMC - 8003 and 8013 series, Elite Ultra (8216), SMC91C90, SMC91C92 and SMC91C94
3Com - 3C503, 3C509
Novell - NE1000 and NE2000
DEC - DE4X5 for the PCI Bus
LANCE and many other chip sets

We also provide a UART driver for SLIP/CSLIP and PPP with Van Jacobson compression.

Adding a new driver is easy. You just need to supply the low level routines and add their entry points into a device table.

Sample programs that demonstrate and exercise each of RTP/IPs features are provided. In most cases you should be able to start with one of these demo programs and add the functionality you need for your application. This flattens your learning curve significantly.


802.11b Drivers

These drivers for the Wi-Fi wireless LAN standard support the PRISM chip set.  Application code is compatible with the same application running over Ethernet.  Supports BSS, IBSS, CAM, PSP and WEP (64-bit and 128-bit encryption through the symmetric key cipher RC4).

Embedded Web Server

This is a full featured HTML server that is specifically designed for embedded systems. With very little additional overhead an embedded system can display its data in nicely formatted HTML tables and pages on any PC connected to it that is running a standard browser. With very little programming you can present professional looking screens from your embedded system. The server supports "CGI" like command that run functions on the embedded CPU and accepts data from HTML forms so the PC can send commands and data to the embedded system.

The web server can be programmed to update fields without requiring constant polling from the client browser.


These option includes the source code for an FTP server, FTP client and a TELNET server. The FTP module uses a virtual file system layer to provide file services. We currently support our own file system (ERTFS), DOS and a memory only file system for diskless systems. Other file systems may be added easily as can pure virtual file systems. The telnet server creates a connection and simply echoes text back to the telnet server. It can be customised to attach to a command interpreter for your embedded application.


This is a port of publicly available PPP code that has been customised for use in embedded systems and has been tightly integrated with the RT-IP network stack. EBS PPP supports LCP, PAP and IPCP as described in RFC's 1331, 1172, 1334 and 1332. PPP runs in both passive and active modes and has been run against Unix, NT/XP, Win 95/98, Chameleon etc. A clearly defined interface to the link layer makes porting PPP to new boards/UARTS easy.


Point-to-Point Protocol over Ethernet allows applications written for PPP to use Ethernet links.


Client for retrieving mail information and mail messages, possibly with MIME attachments, from a POP3 Server.


Provides code to send mail to an SMTP Server including MIME attachments.

Embedded Web Browser

A fully graphical web browser that is based on the PEG C++ Windows interface.


Dynamic Host Configuration Protocol - provides both client and server code to allocate IP addresses from a pool at run-


Simple Network Management Protocol - supports MIB I & II.


SNM Protocol has long been used to configure and monitor remote equipment running over LANs and WANs.   Version 2 provided a rudimentary level of security, but Version 3 tightens this up by limiting access to users on a much tougher authentication basis as well as encrypting data flowing through the system.


The Server Message Block (also known as CIFS - Common Internet File System) provides the ability to file share with Microsoft Windows and LINUX (SAMBA) as well as operating as a means to share peripherals such as printers with the rest of the network.


The NFS client and server provide a rich API for manipulating a mounted remote NFS file system. With the NFS client the embedded system can use a workstation's disk drive as if it were it's own, reading parameter files and reading and writing data directly to the workstation's disk. All necessary file-system primitives are implemented. If the EBS ERTFS local file system is in use, a layer is provided to transparently route requests to either NFS or ERTFS. A comprehensive manual is supplied as is an interactive command shell which lets the user mount and manipulate remote file systems. The command shell also provides documented sample code for using the NFS package.


Secure Socket Layer adds secure encryption to any TCP based dialogue such as FTP, telnet, web servers and browsers.  Based on the OpenSSL standard but adapted for embedded use it provides a wide range of ciphers and powerful tools to test and deliver certification and encryption.


Network Address Translation (NAT) is a method of connecting multiple computers to the Internet or any IP network using a single IP address. This allows inexpensive and efficient internet connections for home users and small businesses.


Simple Network Time Protocol is used to synchronise the clocks on a computer network.

For more Information:

CMX-TCP/IP Suppliers of TCP/IP
MicroNet stack A stripped down TCP/IP stack that is small enough to be suitable for 8 and 16 bit micros.  It has drivers for Ethernet and PPP as well as FTP and Web server packages available.
TCP mnemonics Confused? - Consult our list of TCP mnemonics
TCP/IP Paper Better still download a white paper designed to introduce Embedded 8 & 16 bit engineers to the possibilities and pitfalls of TCP/IP.
ERTFS  ERTFS DOS Compatible file system. Providing a FAT32, DOS and long name support for an embeddable disk file system. Drivers are available for IDE, Floppies, Flash, PCMCIA and CDs.

Home Information Zone
Computer Solutions Ltd
87 Briar Road,  Shepperton,  Middx,  TW17 0JB
Telephone: +44 (0) 77 4342 2526   
Email:      Web:
Copyright 2022 Computer Solutions Ltd