Convert to Papertape V2.2

On the Utilities page I have two programs to convert to MOS Technology papertape format: KIMpaper, a command line utility, and ConvertHexFormat, a GUI app.

All in Freepascal/Lazarus source format, and tested on Linux (Raspberry PI OS) and Windows 10 64 bit. So the programs will run everywhere Lazarus is available (MS DOS, WIndows, Linux Mac OS).

KIMPAPER  is written at the time the Micro-KIM appeared. CLI utility.  Supports Binary to/from Papertape.  Still runs fine on all platforms supported by Freepascal (Windows, MS DOS, Linux etc) after a recompilation, source available.

ConvertHexFormat is a more recent GUI utilitilty with many more 8 bit hex formats as input and output.

There were some bugs of course in older versions. V2 added the ability for multipart hex formats, records having a non-consecutive load address. That seems to wok fine since V2.1
In 2.2 a bug in MOS Papertape format for bigger files is fixed, the end-of-file record (record type 00, total line count) had a bug in the checksum calculation. KIMPAPER is and was correct in the calculation.
But in ConvertHexFormat it was wrong (as it still  is in the well known srec utility in the Unix world!).


PC utilities updated

The PC utilities page has seen an update of th4 Conversion hex formats utility.

Programs to manipulate the binary and hex formatted files of interest for SBC owners. Intel hex, MOS papertape, Motorola S-record, binary, hex conversion fort eh 8 bit world.
Runs on Windows, Linux, Mac due to Lazarus and Freepascal. Source included.


VDU card for Junior with OS65D

Philippe Roehr has remade a VDU PCB as featured in the Elektor Junior articles and put it to work with his OS65D system.



In the Elektor Specials Elektor bus based systems were presented that could be used to build more advanced computers, based on the 6502, Z80 of 65816.

Several names were used for systems, like EC65 and Octopus and you see in these pages many references to these cards, like DOS65, Elektor articles and books

See below for the Elektor Specials with EC65 etc articles.

See also the Z80 Elektuur/Elektor pages

Download here the EC 65 Octopus ROMs, dumped from CPU cards

Elektor bus

From Martin Seine I have received the source of the EC65 ROM and the system disk of the EC65 system

Disassembled, sorted and and somehow aligned the original SAMSON EPROM. The assembler file is here. It will compile byte identical with ca65. All upper case labels match the documentation I have found. The lower case labels are made up by Martin, because they are needed in there. There is a disassembler in the monitor rom, which I did not analyze and hence the disassembly is just strong bytes in that section.

Martin has recovered some original EC65 disks. Here the original disk#5, which is the „System Disk Loys“ as HFE image, which will run on EC65 with Gotek FlashFloppy. Amrtin has now a running EC65 with original system disk. The HFE is the 80-track version and a double side image, but it works as one side as well.

Elektuur Computing 1
Dutch, Octopus/Samson 6502 computer
Sonderheft German
Elektuur Computing 2
Dutch, More 6502 computer
Elektuur Computing 3
Dutch, More 6502 computer
Elektuur Computing 4
Dutch, EC65K and more

Elektuur Computing 5
Dutch, Z80 and more 6502 hardware and software
Elektor Computing 5 German

Another Junior build by Philippe Roca

Another Junior build! By philippe Roca. Faithful reproductions, including EPROM 2708 and PROM 82S33 programmers.

Photos and gerbers of some PCB. Work in progress, I hope to see more photos and Gerbers!

Build an Elektor Junior

Page on building now an Elektor Junior.
Two designs complete with PCB design (Bram Prosman, Werner Beukes), one report of a complete build ( Philippe Roehr).


Junior by Werner

Modern design of Elektor Junior by Werner Beukes (Vintage Computing Group South Africa facebook group)

Gerbers, and Sprint V6 PCD design software layout of main PCB and seven segment display, and a new designed display print for more current displays..
(can be viewed with the demo version or free viewer of Sprint)

Two designs included in this gerber archive: the original reproduced by Werner and one with changes to original design: EEPROM 28C16 instead of 2708, only +5V power supply therefore and CAN crystal oscillator.

Original Junior

EEPROM and Can oscillator

The group build five working Juniors.

Build a Junior

Thw design of the Elektor Junior is well documented in the Elektor articles, books and other articles like the KIM Kenner. In many languages, the archive here is as complete as possible, but you could see some pieces of information in only one language section. The hardware components for the most part are not exotic, especially for the time of publication.
The software in the form of (sources of) the ROMs and applications such as Microsoft Basic and even Operating systems like OS65DV3 is also easy to find.

So with all this information available it is no surprise to see modern versions of the Junior. Some try to stay as close to the original design, others just take the ideas and implement it in a more modern an d convenient way.

Some obstacles in building a Junior are:

  • the original PCB’s are only available as low quality magazine articles quality. And even then be careful, the original article mixed up front an back!
  • the EPROM for the Junior monitor is a 2708 UV EPROM. A very old hard to get part, hard to program and requiring power supplies like -5V and +12V besides to usual +5V.
  • the expansion card used a 82S33 PROM for the address decoding. Also an obsolete part and hard to program.

So what designers can do:

  • design the PCB’s again. Kicad e.g.
  • replace the 2708 with an EPROM like the 2716 or bigger or an EEPROM like the 28C16 or bigger
  • use a GAL or discrete logic for the 82S33
  • use a modern SRAM IC and increase RAM memory a lot
  • modify the address decoding to fit the modern ROM and RAM
  • obtain parts like the 6502, 6532 and 6522
  • replace the hard to get 1 MHz crystal with a can oscillator
  • simplify the power to +5V

Here are some examples of builds:

Junior with KB9 and OS65DV3.3

With thanks to Philippe Roehr from France I present on this page how he got KIM Basic 9 and Ohio Scientific OS65D to work on the Junior

Junior build

Philippe has build a Junior system with at least a main board, an expansion board, 16K Dynamic RAM board expanded to 64K and a floppy controller.

It started with the Junior itself, followed by the expansion card, The monitor software PM and TM were tested.

Floppy controller, RAM card behind.

Junior KB9 Basic

Philippe started with the KB9 binary from the KIM-1 pages.
Philippe then applied the process outlined in the Elektor articles to adjust Basic to the Junior character I/O routines and also improved the speed by adjusting the now unnecessary code that took care of the ROR bug in early 6502’s.

Philippe transferred the binary to the Junior with Ed’s utility KIMTape, producing a KIM-1 audio wave file. The Junior accepts this format, a bit slow but only needed once. After seeing all was well, Philippe wrote the now optimized Junior KB9 Basic to audio wave file, and made a hex dump on the terminal. I picked up the dump, a captured text file form a a terminal emulator, and wrote a conversion program to produce a binary.

All the files here: archive with audio wave file, dump on terminal, binary and conversion software.


After building the Junior, having PM and TM monitor working well, KB9 Basic operational, the next step Philippe took was getting the operating OS65Dv3.3 operational.
He took the steps described by Elektor in the articles with some modern additions.

A Junior able to run OS65DV3.3 needs an expansion card,  a RAM card (his is 64K) and the Elektor floppy controller, which is identical to the OSI one (6850 + 6820 ICs)

Instead of a real floppy drive Philip used the hardware Gotek floppy emulator with the Flashfloppy firmware. And used the manuals images of, and the OSIHFE utility described in the OSI Web forum posts.

Elektor made a bootstrap eprom (ESS515 download here, source in Paperware 2) able to
* load OS65D (V3.1 or 3.3 as far as I know) from floppy
* give basic I/O capability (RS232 and floppy)
* manage hex display and keyboard
* modify OS65 for the hex display after the very first load to fully adapt them to the system ( about 10 bytes to modify)

Here the OS65DV3.3 disk image in native and Flashfloppy format ready to use.

During the second part of december 2020 Philippe added a real floppy controller and added the Ascii Video Terminal (new version of hackaday). With improved moter control of the floppy drive!

VDU board with OS65D

PMV for OS65D source checked by Philippe Roehr



A program, SerialTester,  a guide and test results.

Also updated Prolific PL2303HXA driver misery solution.