Design Consultants : BASIC-52 SBC Introduction

Welcome to the Design Consultants website...

This section of the website describes a single board computer ( SBC ) using a MicroMint 80C52 microcomputer, which is pre - programmed with a powerful 8K BASIC - 52 interpeter... This chip was originally made by Intel as an 8052AH, one of the MCS-51 family of 8 - bit embedded controllers.

There is enough technical information in this part of the website to allow independant construction of this computer... this information is provided as a courtesy to experimenters, students, engineers and/or hobbyists who may wish to construct such a computer, for their own purposes.

In return, the viewer is invited to explore the rest of this ( newly launched ) website, ( April 2004 ) which describes Design Consultants, and the various commercial products and services they provide. ( mostly industrial automation, custom and semi-custom production line systems ) To do this, please use the links provided in the navigation bar at the TOP of this page. ( below the Design Consultants banner ) Those links will open a new window, so the SBC webpage will still remain visible. If you wish to view material that is ONLY related to this SBC project, then please use ONLY the links in the navigation bar located at the BOTTOM of this page.

No liability will be assumed by Design Consultants for any problems associated with this design or project... it is not a commercial product, and it is not available for sale, even as a kit... you must build it yourself, if you want one. Conversely, this design has actually been constructed and tested, and proven to to run properly.

General Description

The BASIC-52 SBC described here has an RS232 port, 8K of RAM, and 8K of EPROM. It fits on a board measuring 2.5 x 3.8 inches, and was designed using ( free ) ExpressPCB CAD software. High quality, plated - through boards for this computer can be purchased directly from ExpressPCB, ( through the internet, with a credit card ) using the CAD files available in this section of the website. ( details on following pages ) The cost is about US$60, for 3 bare boards, using the ExpressPCB Mini-Board service. Additional cost for parts is about US$ 45 per board, and the ( very detailed ) BASIC-52 Programming Manual ( highly reccomended ) is available from MicroMint, for US$ 45.

The features and capabilities of this SBC are really quite modest, compared to almost any other SBC available today, but it provides an excellent self-education opportunity for students and hobbyists... a chance to actually construct and program a complete ( and very useful ) high-level microcomputer, "from scratch", with minimal guidance, no supervision, and no need to learn exotic languages or use expensive software development tools. Despite its relative simplicity, it is also powerful enough to be used in a number of practical applications.

The BASIC - 52 Interpeter

This SBC uses an 8052 chip that is pre-programmed with a high level BASIC-52 interpeter. BASIC - 52 is similar to GWBASIC or QBASIC... it has over 100 instructions in its vocabulary, and includes floating point and scientific notation math, as well as transcendental functions like trigs, logs, and exponentials. Conversely, it has no graphics or “video stuff”, and very limited string features. The next webpage ( link at bottom of this page ) lists some of the commands in the BASIC - 52 vocabulary, to give you an idea of its capabilities.

The computer is operated and programmed entirely through the RS232 port, using a “dumb” terminal, or a terminal simulation program, such as HyperTerminal. ( HyperTerminal is provided free, with all Windows Operating systems... usually in the ACCESSORIES menu ) After “power up”, the BASIC - 52 interpeter expects the first keystroke from the console to be a space bar... this allows the interpeter to calculate the baud rate of the terminal, and it replies to the ( space bar ) keystroke with a “sign on” message.

This computer also has an integral EPROM programmer, which can be used to “save” the BASIC - 52 programs, permanently. The EPROM programmer is invoked directly from the BASIC - 52 interpeter, using the PROG or FPROG commands. The user’s program can be “EPROM saved” in a way that causes the micro to ( power on ) “coldboot” directly from the ( saved ) BASIC program and run it, without any human intervention.... ideal for situations where someone needs a small computer that can be quickly and easily programmed to do a specific task.

Input / Output Expansion

There is also a place provided on this board for an 18 pin PIC microcomputer, ( with connections for reset, crystal, and power ) such as the PIC 16F84, which is a very popular RISC microcomputer , widely used by hobbyists. The PIC chip ( if employed ) can be used independantly, or together with the MicroMint chip... the MicroMint chip has a few unused I/O pins that ( if desired ) can be hand - wired to the PIC, to allow communications from one micro to the other.

The intention was to employ the PIC chip as a fast, intelligent, agile “input / output device”, and leave the heavy “number crunching” to the ( slower ) MicroMint chip. No PIC code has been provided ( here ) to actually do this, since it would be very specific to the type of I/O desired, and ( to a lesser extent ) on the type of PIC chip used. ( there are several models of PIC chips that will fit the footprint provided on this board )

Memory Expansion

Information from various sources indicate that EEPROMS can also be programmed with this chip, but this has not been investigated... The 2864 chip is a EEPROM equivalent ( = same pinout ) of the 2764 chip, used here... In any event, the user can write and run programs in RAM, until the programs are ready to be saved in EPROM... The next webpage has a download program that will allow users to download BASIC - 52 programs that are stored on an IBM PC, using text files created / edited with NotePad.

The BASIC 52 interpeter also has a "PGM" command that allows the program to save information in the EPROM, while the BASIC 52 program is actually running... It looks somewhat complicated, but this feature would allow the computer to “capture” data into the non-volatile EPROM, for later retrieval. PIC chips also have this feature, ( using internal EEPROM ) but their EEPROM memory area is generally very small.

The onboard memory capacity can be expanded to a maximum of 32K of RAM and/or 32K of EPROM, using a ( somewhat crude ) "trick", described on the next page.

8052 Background

The BASIC - 52 Intel chip is no longer manufactured or supported ( as such ) by Intel... it is manufactured ( under license from Intel ) by MicroMint, who widely employs it ( among other chips ) to manufacture their embedded computer systems. The chip with the BASIC - 52 interpeter “built in” is available directly from Jameco Electronics, and also from MicroMint. A comprehensive and detailed manual for the BASIC - 52 programming language ( created by Systronix ) is also available from Jameco and MicroMint.

At one time, Intel also offered a programming language book for BASIC 52, which is very similar to the one from Systronix, except it also included schematic diagrams for ( simple ) computers that use this chip. Most of the design presented here comes from the Intel book.

Systronix is primarily a software house, and they created the interpeter used in this chip. The ( assembly language ) source code for the interpeter can be purchased directly from Systronix for $50, which would allow a user ( with an assembler and a suitable programmer ) to buy the ( cheaper ) “unprogrammed” versions of the 8052, and load the interpeter into it, themselves.

References and More Information

NOTE : Clicking on these links will open a new window.

MicroMint	http://www.micromint.com	home page
	http://www.micromint.com/products/chips.htm	buy chips here
	http://www.micromint.com/manuals.htm	buy programmer's manual here
Systronix	http://www.systronix.com/basic52/basic52.htm	buy interpeter source code here
Jameco	http://www.jameco.com	buy chips and parts here
ExpressPCB	http://www.expresspcb.com	get free CAD tool and buy PC boards here