Is the KIM-1 For Every-1?
OCR'ed August 4, 2003, From
August 1977 Kilobaud Magazine. The documents original formatting has been maintained as much
Robert M. Tripp, Ph. D.
P.O. Box 3
S. Chelmsford MA 01824
Is the KIM-1
For Every-1 ?
... find out if it's for you?
MOS Technology was
recently purchased by Commodore Business Machines, Inc., 901
California Ave., Palo Alto CA 94304. Commodore will be manufacturing
and distributing the KIM product line, and is expanding the production
facilities to double or triple the number of KIMs produced. - Ed.
hobbyist magazines (which is part of my motivation for writing this
article). Second, until recently, the dealer discount structure was
such that very few dealers were interested in handling the KIM-1. This
has been changed and a lot of computer stores are starting to carry
the KIM product line. A number of computer clubs now have formed KIM-1
sub-groups, and there is a national publication, KIM-116502 User
Notes, which is hobbyist oriented and has a rapidly growing
subscription list - currently over eight hundred. Assuming that about
25% of the KIM-1s sold to date have been to hobbyists, then there are
about two thousand currently in hobbyists' hands, and perhaps one
hundred or more being added each month. This is a significant portion
of the computer hobbyist population. I do not know how extensive the
international distribution of KIM-1s is, but I have received orders
for software from Germany, Italy, Sweden, Taiwan and Kuala Lumpur,
Since you have read
this far, you are probably at least considering the KIM-1 for your
own. So let me discuss the features in detail. The 6502 has a good
general purpose instruction set. in many ways similar to the 6800. It
has one of the best sets of addressing modes available. These include
Relative Branching, Indexed Indirect and Indirect Indexed modes useful
in table processing, Stack Addressing, and others. The6502
microprocessor has been selected by a number of independent companies
for use in their hobbyist oriented systems. These include the APPLE-1
by Apple Computer Company; BABY! by STM Systems; the Challenger by
Ohio Scientific Instruments, and Micromind by ECD Corp. to name a few.
These are all assembled systems. The 6502 is also found in a number of
Of course not!
No single microcomputer can serve everyone's requirements. But, the
MOS Technology KIM-1 microcomputer is a well integrated package that
has features which have appeal to hobbyists, educators, and industrial
users. How much do you think it will cost you to buy this complete
computer system with the following features:
- 6502 MOS Technology Microprocessor
- HEX Keypad plus seven Control Keys.
- six digit LED Display.
- 110 to 2400 baud 20 mA Current Loop
- 800 baud Audio Cassette Interface.
- 2K ROM Monitor which works with the
Keypad/ Display or Terminal.
- over 1 K bytes of RAM.
- two independent Programmable
- thirty (30) Programmable I/O Lines.
- extensive Hardware, Programming, and
- capable of expanding the I/O Ports.
- capable of expanding the Memory to a
full 65K bytes.
- completely assembled and tested.
How much does it cost?
Five hundred dollars? Eight hundred? More? Less! Would you believe
$245? Look at the features again. That's quite a bundle of goodies for
the price. If you have priced other systems with comparable features,
you are probably wondering what the catch is. "This is a new, small,
fly-by-night operation which will either have gone out of business or
raised its prices by the time I place my order. Right?" Wrong! The
of the KIM1 is a bit
unusual. MOS Technology which manufactures the KIM-1 also manufactures
the 6502 microprocessor and other related microcomputer oriented
chips. When their 6502 was first ready to be introduced to industry,
they decided to make a powerful "evaluation kit" which, unlike those
offered by most other vendors would be completely assembled, tested,
and would be capable of performing real applications. There are now
over seven thousand KIM-1s in the field. These are being used mostly
by industry, but many units are also being used for educational
purposes and by computer hobbyists.
appreciation of the KIM-1 has been a little slow to develop for two
main reasons. First, there has not been very much published about the
KIM-1 in the
The keypad has
twentythree keys and a slide switch. The keys include the sixteen hex
digits and seven program-dependent functions. Two of the keys are tied
into the interrupt structure providing "maskable" and "nonmaskable"
interrupts to be generated from the keypad. The keypad, in conjunction
with the LED display and the ROM monitor, make it possible to enter
programs directly into memory, to execute programs, and to do
extensive program debugging including single-step testing. All this
without an expensive front panel or external terminal.
The LED display
consists of six independent sevensegment LEDs. These are normally used
to display hex data: four digits of address and two of memory
contents. These same LEDs may be used to output alphabetic messages,
chess board coordinates, decimal calculator values, and so forth.
If you are lucky or
rich enough to own a Teletype compatible terminal you can connect this
directly to the KIM-1. The KIM-1 hardware provides a 20 mA current
loop interface. The KIM-1 monitor provides the software to drive the
terminal at rates from 110 to at least 2400 baud, with some users
reporting good transmission at 4800 baud and reasonable transmission
with occasional glitches at 9600 baud. Baud rate is automatically
determined by the software. There are no jumpers to move or switches
In addition to
providing the standard commands (enter, modify, execute, etcetera
debugging) the monitor also supports punching and reading paper tape.
The user simply sets the starting and ending addresses for the dump
and the monitor takes care of formatting the data, calculating check
digits, and transmitting the data to the terminal. This support makes
easy to save and load
programs via paper tape. Your terminal may be a hardcopy or video
type. K I M-1 doesn't care.
The "piece de
resistance" of the KIM-1 is its built-in audio cassette interface. An
audio cassette is the type of recorder you use to record and listen to
How much does it
Five hundred dollars?
Would you believe $245?
special. The recording
technique implemented in the KIM-1, and described in some detail in
the KIM-1 User Manual, is very conservative and provides tapes that
may be readily interchanged between all KIM-1s, and most types,
brands, and qualities of cassette recorders. (Tapes are not
interchangeable with any other recording system). I have distributed
over three hundred tapes recorded directly from my KIM-1 with only a
few problems. These problems have all turned out to be due to
out-of-alignment cassette recorders.
While the tape dump
routine of the KIM-1 monitor puts data out at the tediously slow rate
of about three minutes per 1 K of memory, there is a software routine
available called Supertape which will dump KIM-1 compatible tapes at
six times the standard rate or about thirty seconds for 1 K bytes.
These tapes may be loaded via the KIM-1 monitor tape load routine at
the higher rate with no modifications. Other tape routines are
possible (and are documented in HELP) which work with the KIM-1
hardware and produce data transfer rates at 800 baud or 100 bytes per
second. The capability of
simply storing and
retrieving programs from standard audio cassettes is a great benefit
to the average hobbyist.
The 2K ROM monitor,
which is contained in the ROM portion of two 6530 multi-purpose chips,
is an integral part of the KIM-1 system and has a number of
clever and useful functions. It provides the standard capabilities of
examining and modifying memory locations from either the keypad/
display or terminal. It also supports single-step program execution
for debugging purposes. Whenever a program is stopped, either via the
stop (ST) interrupt key or while in single-step mode, any memory
location can be examined and modified. To resume processing there is a
program counter (PC) key which restores the value of the program
counter before restarting the program with the execution (GO) key. The
6502 has a BREAK instruction which generates a software controlled
interrupt. This may be used in conjunction with the monitor to insert
a trap into a program for debugging. The monitor also contains all the
software required to control the keypad/display, terminal, and audio
cassette. Many of the monitor's routines may be used by user generated
programs, especially to perform standard input/ output functions. The
ROM even has a special program for fine tuning the audio cassette
interface, should the need ever arise.
There are two sections
read/write memory on
the KIM-1. The main RAM is 1K (1024) bytes of 2102 type static RAM. In
addition, the 6530 multipurpose chips each contain 64 bytes of RAM,
for an additional 128 bytes total. Of these extra memory bytes, 25 are
normally reserved for use by the monitor and 103 bytes are always
available to the user. While a total of 1152 bytes of RAM may not seem
like much memory, you can actually do quite a bit with it. I will list
a few programs which operate in this amount of memory in the software
section. If you require more memory for your application, it is simple
to add memory to the KIM-1. MOS Technology offers two completely
assembled and tested memory boards for direct connection to the KIM-1
with no additional buffers. The KIM-2 is a 4K RAM and the KIM-3 is an
8K RAM. These boards both use the 2102 type static RAM chips. One of
these boards may be interfaced to the KIM-1.
If you require more
than 9K bytes of RAM, MOS Technology offers the KIM-4 which is a board
with buffers and connectors that permit the addition of memory up to a
total of 65K bytes for the system. The additional memory may be any
combination of RAM and ROM. Some of the ROMs to be offered by MOS
Technology include a floating point math package and an
editor/assembler package. Each of the 6530 multipurpose chips includes
a programmable interval timer, which may be set from a few
microseconds to a quarter of a second. They may be tested under
program control or may be set to cause an interrupt on completion of
the specified time interval. These two timers take a tremendous burden
off of the software for many real-time programs, and can be very
useful in programming clocks, music generators, and the like.
Communication with the
outside world" is
handled by the peripheral interface ports of the 6530 multipurpose
chips. Each chip handles 15 input/output lines. One set of I/0 lines
is used by the KIM-1 to control the keypad, display, terminal
interface and audio cassette interface. The other set is available to
the user. These
Now you have your
and it's powered up.
What would you
like to do?
are configured and
programmed as standard parallel interface adapters (PIA). They may be
used to turn devices on and off, to sample external devices, and so
The documentation which
comes with the KIM-1 is pretty good. The KIM-1 User Manual includes
the information necessary to attach your audio cassette and terminal;
descriptions and examples of using the monitor in both the keypad/
display and terminal modes; a simple programming example; a "real
application" example which includes using the programmable I/O ports;
info on expanding your memory and I/O capacity; and the complete
monitor source listing. The Programming Manual is a 170+ page document
which covers the 6502 instruction set, addressing modes, peripheral
programming, and other pertinent materials. The Hardware Manual
contains over 150 pages on the 6502 Microprocessor, the 6530
Peripheral Interface/Memory Device, and the 6520 PIA (which is not
used on the KIM-1). You also get a multi-colored walI chart,
programmers card, etc.
That pretty much covers
the KIM-1 system. You must
supply the power, +5
volt at about 1.2 Amps and -12 volts at about 100 milliamps (the -12
being required only if you are using the audio cassette and may be
supplied by a battery). You can build your own power supply following
the circuit diagram provided in the KIM-1 User Manual, or, The
Computerist has a new
power supply designed specifically for the KIM which can power the
KIM-1 and additional memory. It costs $40 for the completely encased
unit. Or a surplus power supply (adequate for the minimal KIM-1 but no
additional memory) is available for $25.
Now you have your KIM-1
and it's powered up. What would you like to do? Play games? The
Computerist offers two games packages, each of which comes with the
programs on a Supertape cassette tape and includes complete
documentation and source listings. "PLEASE" is an assortment of games
and demonstrations, including a 24-hour clock, a millisecond timer,
the Shooting Stars puzzle, the Mastermind game, Hi-Lo game, a simple
adding machine, an intoxication tester, and more. It runs on a minimal
KIM-1 system and costs $10. The second package is MicroChess which
plays a pretty good game of chess on the minimal KIM-1. It was written
by Peter Jennings and is available for $15.
When you are done
playing games and are ready to put your KIM-1 to work, you can get
"HELP," a series of application packages which
work with the minimal
KIM-1, a terminal, and a pair of audio cassette recorders with relays
for turning them on and off under program control. The HELP packages
include a source and text editor, a mailing list preparation/printing
package, a form letter generator/printer, and an information retrieval
package. Each package comes on a Supertape cassette tape and includes
complete documentation and source listing. HELP is written in a high
level language which permits the user to write his own applications
and/or customize existing applications to suit his particular
requirements. They cost $15 per package, and a relay package
containing all of the components (less mounting board) to control two
cassette recorders is available for $10, all from The Computerist.
Add 4K bytes of RAM and
you can run Tom Pittman's Tiny BASIC. He has aversion specifically for
the KIM-1. There are a number of groups that are actively developing
software for the 6502 and the KIM-1. Lack of software has somewhat
limited the growth
of the KIM-1 as a hobby
computer, but availability is rapidly improving.
One other factor that
has limited KIM-1 growth has been the fact that it does not conform to
the Altair bus structure. Since there are a lot of very nice
peripherals which are Altair compatible, similar capability for the
KIM-1 would be valuable. Forethought Products has just announced the
KIMSI S-100 Interface/Motherboard which connects to any unmodified
KIM-1 computer and converts its signals to the Altair bus format. The
board also contains 8-100 pin slots making it a useful motherboard as
well. The price is $125 in kit form and $150 assembled. The use of
this board will permit the simple addition of a wide variety of
peripherals to the KIM-1 and greatly extend its usefulness to the
Are you hooked? Since
computer stores are now carrying the KIM-1, you can probably see one
locally. Or some other computerist in your area probably owns one and
would be happy to show it off. Have fun. ∎
- MOS Technology, 950 Rittenhouse
Road, Norristown PA 19401, 215/666-7950, Manufacturer of the KIM-1,
KIM-2, KIM-3, ..., 6502, 6530 ...
- KIM-1/6502 User Notes, c/o Eric C.
Reknke, 425 Meadow Lane, Seven Hills OH 44131. Independent hobbyist
magazine covering the KIM-1 and 6502. Published every 5 to 8 weeks.
It contains software routines, games, notes, announcements, etc. ($5
for issues 1-6, $8 foreign subscriptions).
- The Computer Shop, 288 Norfolk St.,
Cambridge MA 02139. 617/661-2670. 4K RAM kit which can be used with
the KIM-1. $74.50 with 2102 type static RAM.
- The Computerist, P.O. Box 3, S.
Chelmsford MA 01824. -617/256-3649. Creator and distributor of the
PLEASE and HELP software packages, MicroChess, and a KIM-1 power
supply and surplus power supply. The Computerist is a monthly
publication dealing with microcomputers in the New England region
from a hobbyist point of view ($6/year).
- Forethought Products, P.O. Box
386-A, Coburg OR 97401. Manufacturer of the KIMSI S-100
- Newman Computer Exchange, 1250 N.
Main, Ann Arbor MI 48104. Distributor for a composite video
peripheral for the KIM-1 ($239).
- The 6502 Program Exchange, 2920
Moana Lane, Reno NV 89509. Games and Utility software for 6502 based
- Johnson Computer, P.O. Box 523,
Median OH 44256. KIM-1 related hardware and software.
- Tom Pittman, P.O. Box 23189, San
Jose CA 95153. Tiny BASIC which will run in 2K bytes on a KIM-1 with
additional memory ($5).