The SYM-1 is a single board "trainer" computer produced by

Synertek Systems Microcomputer Associates, Inc., was founded by Manny Lemas and Ray Holt. It produced the low-cost Jolt Microcomputer, released in 1975. Microcomputer Associates introduces the 6502 based Jolt computer kit for $249. It was later acquired by semi ...

in 1975. It was designed by

Ray Holt Raymond M. Holt is a computer designer and businessman in Silicon Valley. From 1968 to 1970, Ray and his brother Bill Holt were on the Garrett AiResearch's small design team that developed the world's first microprocessor chip set, the 20-bit Ce ...

. Originally called the VIM-1 (Versatile Input Monitor), that name was later changed to SYM-1. The SYM-1 is a close copy of the popular

MOS Technology MOS Technology, Inc. ("MOS" being short for Metal Oxide Semiconductor), later known as CSG (Commodore Semiconductor Group) and GMT Microelectronics, was a semiconductor design and fabrication company based in Audubon, Pennsylvania. It is mo ...

KIM-1 The KIM-1, short for ''Keyboard Input Monitor'', is a small 6502-based single-board computer developed and produced by MOS Technology, Inc. and launched in 1976. It was very successful in that period, due to its low price (thanks to the inexpe ...

system, with which it is compatible to a large extent. Compared to the

, enhancements include the ability to run on a single +5 volt power supply, an enhanced monitor

ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * R ...

, three configurable ROM/

EPROM An EPROM (rarely EROM), or erasable programmable read-only memory, is a type of programmable read-only memory (PROM) chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power s ...

sockets,

RAM Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch * ...

expandable on board to , an

RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such a ...

serial port, and a "high speed" (, the KIM-1 supports about 8 bytes/second) audio cassette storage interface. It also features on-board buffer circuits to ease interfacing to "high voltage or high current" devices. One capability of the SYM-1 is its ability to allow an

oscilloscope An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...

to be added to provide a 32 character display under software control. As explained in Chapter 7 of the "SYM Reference Manual", the vertical input, ground and trigger input of the oscilloscope are to be connected to the "Scope Out" connector AA on the SYM-1 board. The "Oscilloscope Output Driver Software" code provided in this chapter of the manual is to be entered into the SYM-1's memory and executed to enable the oscilloscope display. This code provides control of the oscilloscope display, as well as a rudimentary character set. Resistors R42 and R45 are to be adjusted to refine the displayed image. Synertek sold ROMs which could be installed to add the

BASIC BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

programming language or a Resident Assembler/Editor (RAE). Synertek contracted with a company called Eastern House Software to port their

Macro Assembler Macro (or MACRO) may refer to: Science and technology * Macroscopic, subjects visible to the eye * Macro photography, a type of close-up photography * Image macro, a picture with text superimposed * Monopole, Astrophysics and Cosmic Ray Observato ...

/Editor (MAE) into an ROM. The author of MAE, RAE, and another version sold by Skyles Electric Works was Carl Moser. MAE was sold in various forms not only for the SYM-1 but also for other 6502-based computers including Commodore, Atari, KIM, and Apple. Other forms of MAE included a

cross assembler In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence be ...

for 6800 and 8085—and an offering of these cross assemblers was planned for RAE. One of the more subtle features of the SYM-1 is the use of a look up table in the low memory of the 6502. This provides a vectoring function in its operating system to redirect subroutine calls to various input and output drivers, including interrupt servicing. Users are able to develop their own interface routines, and substitute new vectors for the original vectors in the startup UV-EPROM. This seamlessly maintains the normal operation of the board's monitor and languages such as Synertek Systems BASIC. One of the later home/education computers that uses this concept extensively is the

BBC Micro The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputers and associated peripherals designed and built by Acorn Computers in the 1980s for the BBC Computer Literacy Project. Designed with an emphas ...

produced by

Acorn Computers Acorn Computers Ltd. was a British computer company established in Cambridge, England, in 1978. The company produced a number of computers which were especially popular in the United Kingdom, UK, including the Acorn Electron and the Acorn Archi ...

in the UK. Some of the other computer designers of this era failed to grasp the significance of this elegant use of vectors to the software mapping of new developments in hardware.

See also

References

External links