KIM-1 expansions in Radio Bulletin”

My KIM-1 system in the 80ties was based upon what we had published in Radio Bulletin.
These articles by me and Dick Boer and Paul de Beer document how the expanded system was designed.

Geheugenuitbreiding voor de KIM, November 1977, Dick de Boer
Geheugenuitbreiding voor de KIM nov 77
EPROM Programmer 1978
4 Kbytes EPROM-kaart september 1981
Geheugenuitbreiding voor de KIM dl 1 sept 1979
Geheugenuitbreiding voor de KIM dl 2 oct 1979
Knutselen met cassettedeck maart 1980
Moederprint Juli 1981
ACIA6850 Seriele in- en uitvoer September – November 1983
Parallele in- en uitvoer VIA en PIA Mei 1984

Grafisch TV-display dl 1 sept 1978
Grafisch TV-display dl 2 nov 1978
Grafisch display monitor voor de KIM 1979 1981
Lijnen op het grafisch display Februari 1982

MDCR voor de 6502 April 1984

Published in the Byte Book of Computer Music, 1979. Written by Peter H. Myers.

Scanned article here.

The listing is converted to MOS Technology standard assembler source. The resulting code compared to the publsihed code.
Here and archive with source and papertape binary.\

Published in the Byte Book of Computer Music, 1979. Written by Peter H. Myers.

Scanned article here.

The listing is converted to MOS Technology standard assembler source. The resulting code compared to the publsihed code.
Here and archive with source and papertape binary.\

I started writing about my interest in electronic since 1970. And in 1977 the magazine (Dick de Boer!) introduced me to the KIM-1, and that enhanced my joy with electronics with computing.
At the university in these days electronics and computer science also came together.

We have published many articles around the KIM-1. Alas in Dutch and only on paper. Published on this website, see the Radio Bulletin pages.

Many of the articles deserve a wider public, the KIM-1 and its clones are used by a broad international public.
So I started a new project: translate the articles to English and make the software available in assembler and binary format.

Follow the progress here, articles already published are:

Mastermind on the KIM
Morse decoding with the KIM
Melodiant
Frequencymeter
EPROM Programmer

The original articles were scanned from the magazine pages. converted back to text with OCR and translated to English.
The documents in Dutch and English are also published again in PDF format.

If a program listing was included the assembler source is reconstructed in modern MOS Technology syntax. The binary output is compared to the printed binary code and a papertape formatted binary is included.

This is a work in progress. Each article takes half a day of work. See the page on Radio Bulletin articles of candidates to be processed later. See the list of articles on the TODO list.
The articles describing the expansions we designed for our KIM-1s at the magazine are on a separate page.

Downloads available for every article:
– the original scanned article in Dutch
– the Dutch OCR’ed and recreated article
– the English translated form the OCR result and recreated article
– an archive with source and binary if applicable

Articles here:

• Mastermind on the KIM
• Morse decoding with the KIM
• Melodiant
• Frequencymeter
• EPROM Programmer
• KIM Timer and Clock
• Zero page shifter
• Telex Monitor Program
• Gregorian Clock
• PIA Buffer
• My KIM-1 expansions in Radio Bulletin

Mastermind on the KIM

Radio Bulletin December 1977

You are probably familiar with the well-known game Mastermind. Normally this game is played by two people, with only one person actively trying to guess a hidden code. The second person has the passive task of indicating, with black and white pegs, whether the chosen colours are correct and whether they are in the right positions. Replace the colours with digits, the black and white pegs with letters, and the KIM takes the place of the passive player. At your command, it chooses a secret colour combination and uses letters to indicate how many digits have been correctly guessed. A special “cheat button” makes it possible to peek secretly behind the screen; the consequence, however, is that the turn counter is increased by 30 points.

Runs on the unexpanded KIM-1 with keypad and seven segment display.

	Mastermind on the KIM Radio Bulletin 1977 original scan
	Mastermind on the KIM Radio Bulletin 1977 English
	Mastermind on the KIM Radio Bulletin 1977 Dutch
	Mastermind source and binary

Morse decoding with the KIM

Radio Bulletin July August 1979

It may be quite nice to be able to say that you are the owner of a microcomputer (if things continue as they are now, in a few years this will be just as commonplace as owning a pocket calculator is today), but even nicer is to also own programs and to be able to spend a number of useful and above all pleasant hours with the device. The following program, written for the KIM, may contribute to this. It makes it possible to display received Morse signals as ‘readable writing’ on the KIM display. Although with a seven-segment display by no means all letters and punctuation marks can be formed, and therefore certain symbols had to be found for these characters, after some practice it is quite possible to read messages sent in Morse code from the display. The program can be used not only for displaying received messages, but also for practising sending and for checking the sending technique. From what is shown on the display one can determine what mistakes are being made while sending

	Morse decodering met de KIM July Augustus 1979 original scan
	Morse decoding with the KIM July Augustus 79 Radio Bulletin English
	Morse decodering met de KIM Juli augustis 1979 Dutch
	Morse decoding with the KIM source and binary
	Morse decoding circuit in Kicad By Roland van Straten

Melodiant

Radio Bulletin august 1977. Dick Boer.

The Melodiant plays a complete melody of up to 256 tones on a command given by you. The display shows which note is being sounded. This makes the Melodiant a very versatile instrument. For example, you can play duets together with the Melodiant by typing in one of the two voices beforehand. The advantage over a tape recorder is that the melody can be played at any desired tempo, which can make practicing easier. What about the Melodiant as a music teacher? A note appears on the display, and the student must try to sing or whistle that note. Afterwards, the loudspeaker can be switched on to check. The Melodiant will also flawlessly play back the most difficult rhythms, slow or fast as needed.
But the possibilities do not end there. We can make the Melodiant play so fast that the individual tones are no longer recognizable. This can produce the strangest sound effects.

	Melodiant Radio Bulletin Augustus 1977 original scan
	Melodiant August 1977 Radio Bulletin English
	Melodiant Augustus 1977 Radio Bulletin Dutch
	Melodiant Radio Bulletin Aug 1977 source and binary

Frequencymeter

Radio Bulletin January 1981 M. Dohmen, R. Koekoek

The program described here can measure a frequency up to, mind you, 100 kHz, with a deviation of no more than one cycle in 65536. The frequency is read out in five digits. The program was written for the KIM, but is also well suited to other 6502 microcomputers, notably the SYM and the Junior. Once started, the program measures a frequency continuously when key “6” is pressed, and once when key “0” is pressed.

	Frequentiemeter Radio Bulletin Januari 1981/td>
	Frequency meter Radio BulletinJanuary 1981 English
	Frequency meter Radio BulletinJanuary 1981 Dutch
	frequencymeter source and binary

EPROM Programmer

Radio Bulletin 1978 J.M. v.d. Peijl

The EPROM (Erasable PROM) can also be programmed by the user. In addition, it can be erased again using ultraviolet light. Thus an EPROM containing obsolete or outdated programs can simply be erased and reprogrammed. The most popular EPROM at present is the 2708 (1K byte), which has fallen considerably in price recently, partly because of its successors, the 2716 and 2732, with 2K and 4K bytes respectively. Programming such an EPROM is a task that the KIM can handle very well. In this first part you can read how, by adding a few simple circuits, the KIM takes over the job of an expensive PROM programmer. In a subsequent article we will describe several practical versions.

	Eprom programmeer apparaat Radio Bulletin Juni Juli 1978 original article
	EPROM programmer Radio Bulletin June July 1978 English
	Eprom programmeer apparaat Radio Bulletin Juni Juli 1978 Dutch
	Eprom programmer source and binary Radio Bulletin Juni Juli 1978 Dutch

KIM Timer and Clock, Radio Bulletin May 1980, Herman Perk

While working with the KIM I once encountered the problem that a clock had to be maintained during the execution of a program. Not for the KIM itself, but for a system with the TIM monitor, namely the BEM-bus-based 6502 system from the company Brutech, which is highly recommended for its high quality and well-thought-out design (hence the prices). At the end of 1978, however, both the KIM and the BEM system were still lacking 6522 VIAs with their versatile timers, unlike the SYM and AIM-65. Worse still, the TIM monitor uses the only timer available in the system for communication with the terminal. If I nevertheless wanted to use the 6530 timer for the clock, I had to write my own program for communication, based on the so-called software timing loops. I did so, since I no longer needed TIM itself for the result. As for the timer (those of the 6530 and 6532 are identical), the “obvious” operating instructions say nothing about a possible “free-running” mode as would be usual for a clock and as is described for the 6522

	KIM Timer and Clock Radio Bulletin May 1980 Original article
KIM Timer and Clock May 1980	KIM Timer and Clock May 1980 Radio Bulletin May 1980 English
	KIM Timer and Clock May 1980 Radio Bulletin May 1980 Dutch
	KIM Timer and Clock source and binay

Zero page Shifter

D.M. de Boer, Augustus 1979 Radio Bulletin

	Zero Page shifter Original article
	Zeropage shifter August 1979 English
	Zeropage shifter August 1979 Dutch
	Zeropage shifter RB August 1979 Source and binary

Telex Monitor Program

Radio Bulletin April June 1981 M.B. Immerzeel

Those who own a “simple” microcomputer such as the KIM or the SYM, and who also own a telex transceiver, will long since have thought about using the telex as a terminal and may already have a program for that purpose. However, most of these programs are limited to noting down addresses with their contents one below the other, and are therefore not particularly economical with paper. The program described below offers the following possibilities:
a. Loading a program in hexadecimal code.
b. Loading ASCII characters.
c. Printing memory contents as hexadecimal numbers.
d. Printing ASCII characters.
e. Starting a program.

	Original article Radio Bulletin April June 1981
	Telex Monitor Program Ènglish
Telex Monitor Program Dutch	Telex monitor RB June 1981 dutch
	Telex Monitor Program source and binary

Gregorian Clock

Radio Bulletin May 1981

This clock program is very short and will certainly prove useful to many people. It counts in decimal and keeps track, in decimal, of quarter seconds, seconds, minutes, hours, day of the week, date, month, year and century. Leap years are taken into account!

	Gregoriaanse klok Original article Radio Bulletin May 1981
	Gregorian Clock English
	Gregorian clock Dutch
	Gregorian clock source and binary

PIA Buffer

Radio Bulletin November 1983

The outputs of the user PIA are not suitable for connecting devices to. A buffer stage is necessary to achieve this. I believe that the term “student-proof” applies to this circuit

	PIA-buffer Original article Radio Bulletin November 1983
	PIA Buffer Nov 1983 Dutch
	PIA Buffer Nov 1983 English

TODO list
Automatische register uitlezing feb 1978
Mini assembler maart april 1981

Acquired August 2026, as built in a KIM-1 with KIMSI system.
Page updated September 2026 with scans and KIM-1 source of the original manual and brochure.

He was not so happy with the NTSC composite signal of this Replica 1. So he reworked the source files of the Propeller to support PAL formatted video.

The thread on the design is here.

EXPLIT created a github archive as a fork of the github from Vince Briel, with original and PAL adapted source files.

More on the Apple 1 Replica’s here.

This is how the PAL output looks: sharp, no artefacts, black on white:

Photos of the build by EXPLIT:

He was not so happy with the NTSC composite signal of this Replica 1. So he reworked the source files of the Propeller to support PAL formatted video.

The thread on the design is here.

He created also a github archive as fork of the github from Vince Briel, with original and PAL adapted source files.

This is how the PAL output looks: sharp, no artefacts, black on white:

Photos of the build by EXPLIT:

I acquired a KIMSI in August 2026. It was build into a plexiglas/aluminium case, with a KIM-1 (Rev G) and a ‘microcalculator board’. I took the system apart, no room to store the big ugly thing.