KIM-1 expansions in Radio Bulletin”
My KIM-1 system was based upon what we had published in Radio Bulletin. These articles by Dick de Boer, Paul de Beer and me document how the expanded system evolved, using an extended version of the BEM bus.
Articles here:
De KIM-1
The article that started the KIM-1 articles!
Write your own programs
Radio Bulletin September 1977
The most enjoyable work is of course writing your own programs, making the KIM I do exactly what you want. Now, programming is not that easy for someone who has never done it before. Especially at the beginning, the aspiring programmer works in such a disorganised way that in the end he no longer knows which instruction is at which address. It is therefore important to set up a program in a clear, orderly way and to write down every change. In this article we will use an example to show how this is done. However, we leave the exact working-out to the reader, because here too it is certainly true: practice is the best teacher!!!
Programming step by step
A five part article in Radio Bulletin 1978 to 1979
Since RB’s KIM campaign in August of last year, the number of KIM owners has grown considerably. Readers’ reactions show that some of the new KIM owners are already getting the hang of programming quite well. Another group, however, is clearly lagging behind: the people who cannot find the ‘beginning’. That is very understandable when you consider that, although the computer is built from electronics, programming is completely new territory for many. In this article RB will therefore try to help this group on their way.
Memory expansion for the KIM
Radio Bulletin 1977/ Introduction of the BEM bus with a 1K RAM card.
Although the 1K memory space of the KIM 1 is very generous for a beginning programmer, sooner or later the need for more memory will arise. This allows larger programs to be written, or more programs to be held in memory at the same time.
There are several ways to expand the memory. You can buy a number of ICs yourself and mount them on a home-made circuit board, which is by far the cheapest solution. The nicest solution is simply to buy a ready-made memory card; you then have a professional piece of work, with the reliability that goes with it.
A 1K EPROM card is designed, based upon the BEM bus.
Prototype 1K RAM boards
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. We will describe several practical versions.
Audio cassette recorder
Radio Bulletin March 1980
Accompanied by the slogan ‘Tophit 1980’, Radio-Service Twenthe is offering a built-in front-loader cassette deck for the low price of f 32.50. Radio-Service Twenthe often manages to offer interesting industrial surplus to the amateur at a reasonable price, and this cassette deck is another example of that. A handy tinkerer can easily turn this cassette deck into a mono cassette recorder; for personal computer users this is a golden opportunity to get hold of suitable cassette recorders with a tape mechanism.
The two cassette recorders as data recorder for the KIM-1
Memory Expansion for the KIM
With 4K RAM card and busbuffer print.
Radio Bulletin September October 1979
Memory expansion for the KIM has already been discussed twice. The first time, in the November 1977 issue, it was shown how RAM could be added with the BEM-1 board, a kit for 2K of static RAM. The second time was in the July 1978 issue, when a board design for a 2K EPROM card was published, with the same bus connections as the BEM-1 card. This series now continues with a 4K static RAM board, also with the same bus. Connecting the RAM to the KIM requires address decoding and a bus buffer. A board has been designed for this as well.
The 4K RAM production.
The 4K RAM prototype.
Motherboard, memory support for 6502 systems
Radio Bulletin July 1981
Radio Bulletin has already described several ways to expand the standard memory of 6502 systems such as the KIM. Published so far are a 2 Kbyte static RAM card, the BEM-1 board (November 1977), a 2 Kbyte EPROM card (June and July 1978) and a 4 Kbyte static RAM card (September and October 1979). All these designs use the bus as used on the BEM-1 board, but with a number of additions, which will be needed mainly for the 4 Kbyte EPROM board in a forthcoming issue. This article describes a motherboard into which all these cards can be plugged.
Parallel in- and output PIA 6820 and and VIA 6522
Parallel in- and output PIA 6820 and and VIA 6522
Radio Bulletin May 1984
The subject of this article is a family of parallel input/output ICs: the PIA 6820, 6821, 6520 and the VIA 6522. These are widely used ICs, and not only in 6500 and 6800 microprocessor systems. Besides the general hardware characteristics of the PIA and the VIA, a practical implementation is presented
Prototype of PIA VIA card
ACIA6850 Serial in- and output
Radio Bulletin September October November 1983
Prototype serial interface
Mini-digital cassette recorder interface for the 6502
This article describes an interface between a 6502 computer and one or more MDCRs, and a number of elementary routines in 6502 assembler for using the MDCR. The software has deliberately been developed to be as universal as possible
4K EPROM card
Radio Bulletin September 1981
As part of further memory expansion for 6502-based systems such as the KIM, Junior, SYM, etc., a 4 Kbyte EPROM card is described here. It is suitable for two types of EPROM, the TMS2516 and the 2716, the latter being the most common. The board plugs into the motherboard published in a previous issue of Radio Bulletin. Combined with the EPROM programmer (RB December 1980 and January 1981), this gives you the tools needed to put programs such as an assembler, a high-level programming language, a bootstrap loader or your own developments into ROM and run them from there.
Graphical TV Display
Radio Bulletin, 4 parts, September 1978 – November 1978 – February 1979 – March 1979
Just imagine: an ordinary TV on which you can make your own drawings. These can range from plain text and graphical representations of mathematical functions to a drawing made by a toddler. For this purpose the TV screen has been divided into a grid of 256 × 256 dots!! Such a grid gives roughly the maximum resolution that can be displayed on an ordinary TV (without interlacing). The applications are countless. The computer hobbyist gets a particularly fine output device, a kind of combination of plotter and teletype. For those who do not own a computer, it is possible to expand this unit into a hobby computer.
My Graphic Dispkay with the hardware scroll addition.
ASCII characters on the Graphical Display
A subroutine to display an ASCII character (upper and lowercase) on the Graphical Display.
Unpublished code, 1983 Hans Otten
Characters (Letters) on the Graphic Display
Radio Bulletin May June July 1981
In the previous series of articles on the home-built graphic TV display, a lot of attention was paid to the hardware of this display. Two important routines were also discussed, namely switching on or off one of the 65536 dots and clearing the picture. But… a display is not a display if no text can be shown on it. That is why this article presents what is perhaps the most important piece of software written for this display: ‘drawing’ letters, with unprecedented flexibility.
Lines on the Graphical Display
This article describes a program that draws straight lines on the graphic display. Only the start and end points of the line need to be entered; the program then draws the line.
Graphical Display Monitor
Radio Bulletin 1981 – 1984 4 parts
The set-up is as follows. The complete package consists largely of subroutines that are controlled by a small main program. These routines are simply placed one after the other in memory. Those who do not want a complete monitor can use these subroutines separately, since they can also prove their worth on their own. This produces a “subroutine arsenal”. Those who do want a complete machine-language monitor, however, will have to make a few changes to, and additions to, the hardware.
1. As you may know, it is possible to build a hardware scroll-up on the GD. This needs 4 ICs. Without this extension the monitor does not work.
2. The monitor needs a larger keyboard (28 keys). I may assume, however, that if you do not have an ASCII keyboard you have long been planning to buy a more extensive keyboard. Further on in this article a keyboard is described that is very cheap and more than adequate (for about f 30.00 you have a well-working keyboard). A real ASCII keyboard is of course still recommended.
3. Not necessary, but very handy, is a circuit that allows a loudspeaker to be switched on and off by software. This can be useful in combination with the monitor (think for example of a beep after CRLF has been given).
Digiscope for 6502 systems
Radio Bulletin April 1983
Those who have a Graphic Display and a computer system based on the 6502 will discover in this article that the possibilities of this combination are almost unlimited. The January 1980 issue described a frequency meter, which once again showed that a computer can prove its worth in the hobbyist’s electronics lab. The program discussed here, as an addition to the frequency meter, will for many be an answer to the question: “Should I buy a computer?” What we have here is a so-called “digiscope”. This is a kind of oscilloscope that makes digital signals visible on the graphic display.
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48K RAM card
Radio Bulletin 1982
If you want to work with Basic, Forth, editors etc., you need a lot of memory. It makes no sense to build this up from 4K memory cards. A cheaper and better solution is to use dynamic RAM ICs.
The industry-standard 4116 is a 16K × 1 dynamic RAM chip. With eight of these 16-pin ICs you get 16 Kbyte, and with 24 ICs 48 Kbyte. The dynamic RAM card for the 1802 fits into a bus connector of the Cosmicos computer. The card is also easy to use with other 1802 systems; it is then connected with 24 wires.
What is remarkable is the simplicity of the dynamic RAM card. This is because a special IC has been used for timing and refresh: the Intel 8202. Since this controller and the memory ICs functionally form a self-contained unit, use with e.g. KIM or Junior computers is certainly possible by adapting the addressing logic. You don’t need to design a PCB for that part – no small job saved.
48K RAM card Interface for the 6502
Radio Bulletin September 1983
After tinkering for some time with 4K RAM cards and the accompanying tangle of wires
and connections, my eye was caught by the 48K RAM card for the 1802 published in the
March 1982 and following issues of RB. This o%ered the chance to solve the memory
problem once and for all, so the possibility of adapting this card to the 6502 processor
was studied. By leaving a number of ICs o% the original board and adding a small
interface in the space freed up, you get 48K of RAM for your 6502 system – a real wealth.
