Another update to the Simulators

KIM-1 and TIM Simulator have seen a small update.
Improvements on console handling and little annoyances. Focal added as programming language, for KIM-1 and TIM!
The Apple 1 Monitor, wozmon is now available as a Setting to be added the not used space in the 6530-003 tape ROM.

KIM-1 Simulator 1.4.0
TIM Simulator 0.6beta
Convert Hex Formats 2.8 (bundled also with simulators)


Focal-65 V3D for TIM and KIM-1

Focal on the 6502, a page on this small language, originating for Digital Equipment.
A small interpreter (about 5K) for a convenient interpreted language. Floating point 9 digit accuracy. At least two versions were distributed around 1977, one by Aresco, called “Focal V3D” and another by the Program Exchange as representative of the Denver 6502 Group, often called “Focal-65E”

Latest addition is a reconstruction of the source, by Wayne Wall of the Denver 6502 Group in 1977, of Focal V3D for the TIM to binary, and a port to the KIM-1.
Based upon a listing of the TIM Focal-65 from 1977 and a Focal-65 User manual, repaired and cleaned up.
And that enabled the reconstruction of the soource Focal-65 V3D as distributed by Aresco!

Read all about Focal-65 here!


Focal-65 V3D for TIM and KIM-1

Focal on the 6502, a page on this small language, originating for Digital Equipment.
A small interpreter (about 5K) for a convenient interpreted language. Floating point 9 digit accuracy. At least two versions were distributed around 1977, one by Aresco, called “Focal V3D” and another by the Program Exchange as representative of the Denver 6502 Group, “Focal-65″ or FCl_65” or “FCL-65E”

Information from the German 1981 article in MC Magazine, see the articles, indicates the existence and sale of Focal versions by the 6502 Program Exchange:

  • FCL-65 and FCL-65E with Mini userguide
  • My version from Aresco Focal V3D, 1-oct-1977 binary and userguide
  • Focal V3D for TIM, listing known and available on this page
  • Focal-65 V3E 1-oct-1979, Apple II, source listing known at MC Magazine in 1981
  • V4 for Apple, listing known and in possession of Wayne Wall, not public available

I suppose this list is incomplete, other versions may have existed. None but my binary of Aresco Focal-3D, the Aresco V3D Userguide, a User Guide by the Denver 6502 group and a listing of Focal-65 V3D for the TIM survived and is available.

Latest addition to this page is a reconstruction of the sources, of Focal V3D for the TIM to binary, and a port to the KIM-1. Also the Aresco version source is reconstructed and identical to the tape dump of 1978.

On this page you will find:

  1. My experience with Focal-65 as started in 1979
  2. Reference material: User manuals, listings
  3. Magazine articles about Focal-65
  4. Reconstructed sources of Focal-65 for TIM and KIM-1
  5. Reconstructed source of Focal-65 for the KIM-1 Aresco version
  6. On the origin of Focal-65

My experience with Focal-65 started in 1979

In 1979 my good friend Anton Muller, at a meeting of our Dutch 6502 KIM Club, surprised me with a package Anton had imported from the U.S.A. : Focal V3d by Aresco.
The package came with a cassette tape and a user manual. We installed it on the KIM-1 and played with it. Impressive what was done in about 5K!
Floating point, string handling, a trick to suppress the hardware echo of TTY input.
After an article in our club magazine more members of the club became Focal-65 users and published articles about it.

This version of Focal-65 has survived. I have dumped a working version from cassette in 2004 (not the original alas, but a working copy with a bit too much) and scanned the user manual.
Manual and binary version have been available on this website now several years. Also I added DEC Focal manuals, Digital Equipment Corp. developed and sold Focal as a product for the PDP computers. In the KIM/6502 User notes articles were published on making Focal even more interesting, also published here.

When the KIM Simulator became usable, I tested Focal and saw that suppressing the TTY echo worked, but the wait for keyboard input loop preceding the read character routine did not. So I added a setting to let Focal-65 survive that loop. So Focal-65, Aresco version, runs unaltered on the KIM-1 Simulator!

The FOCAL programming language

In 2023 a source listing appeared, thanks to Paul Birkel, of Focal-65, programmed by Wayne Wall and friends in 1977. Target system is a TIM such as Jolt or Superjolt. I typed in that listing exactly with modern assembler syntax and made that version operational.
Here I present several reconstructed versions, for TIM (653-004) such as Jolt and KIM-1 based systems.
– A TIM/Jolt/Superjolt system needs minimum 8K RAM in lower memory.
– The KIM-1 needs memory, minimum 8K, from $2000 and up.
See below for the TIM version and a port to KIM-1. These are 90% identical to the Focal-65 V3D Aresco version, so that was the start to recreate that source too .

Reference material for download

First some downloadable reference material.

DEC-08-AJAB-D PDP-8-I FOCAL Programming Manual.
Focal by DEC is the beginning of all Focal implementations. A typical DEC manual, easy to read, complete, well organized.
DEC-08-AJBB-DL Advanced FOCAL Technical Specification April 69
This manual is where Wayne Wall got his design. From the flowcharts and labels, similar names and concepts can be found in the Focal-65 source
Focal-65 users guide V3D, by Aresco
Focal-65 Users Guide V3D by the Denver 6502 Group.
Cleaned up version made by me.
TIM Focal-65 V3D source listing
Cleaned up version made by me.

Articles on Focal-65

KIM/6502 User notes
Articles from the magazine, Focal corner

  1. Introduction to FOCAL, 6502 User Notes 12
  2. Improve on echo problems with KIM TTY, 6502 User Notes 13
  3. Make room for enhancements, extend to 8K, User Notes 14
  4. Speed it up, 6502 User Notes 15
  5. Cassette save/write an LED display listing, 6502 User Notes 16

KIM Kenner
Introduction to FOCAL, how to program, Dutch

Compute II
Modify and Move FOCAL 65-E into EPROM, Compute II Issue 3

MC Magazine
German article on Focal-65, has interesting information on versions

Working versions, reconstructed from sources

Denver 6502 Group Focal for TIM

In 2023 a listing of Focal-65, by Wayne Wall, for a Focal-65 version for the TIM, showed up, thanks to Paul Birkel.
A low low quality scan, so I cleaned it up, improved contrast, removed artefacts and cropped it. The result is readable, but not fit for OCR.

TIM Focal-65 V3D source listing
Original printed listing 1977 by Wayne Wall. Cleaned up version.

I typed this source in, exactly as the listing: uppercase, same comments, same line numbers.In this way I honor the original author and also enable checking of the binary result.
I did change the assembler syntax to a modern assembler. The original was written for PAL-65, an assembler by Wayne Wall in PDP macro assembler format.
When it assembled I compared the binary out to the binary in the listing by hand. Of course typos and the curse of direct addressing, the #!, caused some extra work.
The result was a binary with the same length. as shown in the listing.

Then the binary was loaded in my TIM Simulator, with a small external patch for the ‘no echo’ input character routine in the source. The TIM has ‘software echo’ hardcoded in the monitor for reading a character from TTY, so the monitor code is copied with optional echo.
It runs!

Focal-65 for the TIM, here the source as typed in, listing, binaries in Intel hex and Papertape format and the TIM Simulator patch.

Denver 6502 Group Focal for the KIM-1

To illustrate how easy it is to adapt Focal to other 6502 systems, I ported the TIM version to the KIM-1.
Changes required:

  1. Program moved from $1000 to $2000
  2. Replaced the TIM I/O package with a KIM-1 version: IRQ/BRK vector, no echo character input (partly taken from the Aresco disassembly for character output
  3. Further no changes, same line numbers, same size

This version runs fine in the KIM-1 Simulator with the Focal V3D setting.

Focal-65 for the KIM-1, here the source as typed in, ported to KIM-1, listing, binaries in Intel hex and Papertape format

Aresco Focal-65 V3D

Here the original Aresco Focal V3D dump from cassette. Note that the dump contains a bit more than necessary. The zeropage is completely dumped, and filled in by a running Focal session.
It runs on a KIM-1 and on the KIM-1 Simulator with the Settings – Type of Break setting set to Focal V3D.

First attempt to get a source, unfinished, does not assemble, but informative.
Disassembled source by Paul R. Santa-Maria (2004) and Hans Otten (more comments) (2022).

Focal-65 users guide V3D, by Aresco

Reconstructed source of Focal-65 for the KIM-1 Aresco version

With the source of the KIM-1/TIM and the binary of the Aresco version I have since 1978, it was an easy job to reconstruct the source of the Aresco version.
By comparing the binary output of the assembled source and the binary of the tape, differences can be seen and fixed in the source.

The interpreter code is 100% identical to the tape dump (minus the extra unused bytes saved at the end). Zero page is clean.

The code runs in the KIM-1 Simulator with the Focal V3D setting. No surprise, the binary of the tape dump also runs and the binaries of the code are identical.

Focal-65 for the KIM-1, Aresco version, here the source , listing, binaries in Intel hex and Papertape

The history of Focal for the 6502

Excerpt from the history of the Denver 6502 Group.
In 1975, Denver was a hotbed of computer activities. There was a new computer club called the Denver Amateur Computer Society (DACS), and every meeting was packed with radio amateurs and hobbyists anxious to learn about this exciting new technology. DACS was dominated by Intel 8080 based computers, but there were a few people interested in the 6502. Wayne Wall was one of the first to appreciate the power and speed of the 6502, and he decided to form a subgroup of DACS for 6502 users.

Wayne was a genius assembly language and systems programmer who worked at the Colorado School of Mines. He began holding meetings every Tuesday night at the School of Mines Computing Center for anyone interested in the 6502. At first it was called the 6502 sub-group of DACS, but as time went on, it became the 6502 Group.

All told, there were probably about 100 members, but on a typical night, 30 to 40 people would crowd into the meeting room, anxious to hear Wayne’s latest ideas and see his demonstrations. He was famous for his magic shows that invariably consisted of doing something hitherto unimaginable like simulating human speech with 13 bytes of assembly code. Wayne quickly gained the well deserved reputation as a computer wizard.

Most members of the group owned Digital Group systems. The Digital Group was a local company that had a short but spectacular career manufacturing computer kits. They were powerful, easy to assemble and way ahead of their time, with memory-addressable video cards, system monitors and relatively large memory boards. In addition to the Digital Group systems, the group had a scattering of Kim’s, Tim’s, Jolt’s and even a few odd homebrew machines.

At the time, there was virtually no software available for the 6502. All programs had to be tediously hand-assembled and typed into the machines. Wayne decided that his first task was to find a way to deal with this problem.

The School of Mines had a huge black mainframe called a PDP-10, and Wayne wanted to use the power and capabilities of this computer to write 6502 code. The first possibility was to use a FORTAN cross-assembler that was available from MOS Technology, but it was slow and buggy. Instead, Wayne chose to write 6502 macros for the PDP-10’s “PAL” assembler. After a few days work, Wayne had a fast new assembler that he called “PAL-65.” Suddenly we had the ability to write relatively large assembly language programs for the 6502.

Initially, Wayne cranked out a series of assembly language games. The first was a simple text based game where you shot arrows at a mythical beast called a Wumpus. Most of our computers had between 512 and two kilobytes of memory, but as Wayne’s games grew in complexity, we struggled to keep up, spending our nights soldering memory chips onto circuit boards.

Wayne now turned his attention to a high level language. The Intel based microprocessors had a version of BASIC written by Microsoft. Wayne decided that we should have a similar language, and he chose to write a version of the DEC language called FOCAL. Even though it was a relatively obscure language, FOCAL had some subtle advantages over BASIC, the biggest was its ability to evaluate strings as expressions.

Wayne wanted FOCAL to be a group project, and one evening he showed up with a stack of photocopies of the DEC flowcharts for the language. His plan was to assign each section of the chart to one of the 6502 Group members. We were supposed to go home, write 6502 assembly code for the section, and in a few weeks, we’d have an operating version of FOCAL. Unfortunately, Wayne had overestimated our skills. Most of us had been assembling code by hand and had no idea how to work from a flow chart. In the end, Wayne and Bob Ulshafer did most of the coding.

When it was finally finished, FOCAL was a big breakthrough. Suddenly we had a true programming language. Complex new games began to appear on our computers including a version of the famous mainframe game Star Trek, written by Larry Fish. Over the next few weeks Wayne wrote a five-byte floating point package for FOCAL based on a Dr. Dobbs article. With the new floating point power, simulations and mathematical programs sprouted up everywhere.

With thanks to Paul Birkel for the scan of the listing.

A TIM (6530-004) Superjolt simulator update, also KIM-1 Simulator

A TIM (6530-004) Superjolt Demon simulator.

Version 0.4. TIM Superjolt Simulator V0.4, Tiny Basic working!

Since the TIM Simulator and the KIM-1 Simulator share a lot of code, also the KIM-1 Simulator got an update, to let Tiny Basic work better: V1.3.8 is available.

The bundled Conversion 8 bit hex formats is now at version 2.6.

I have since yesterday a Raspberry Pi 5. Great little machine. Very grown up installation. Lazarus works fine with the usual trick of first the apt install version and then fpcupdeluxe for a newer version.

The TIM and KIM-1 Simulator work fine on the Pi 5, so a Raspberry Pi 5 is now included in the distributions.

Superjolt and TIM 6530

I have acquired 3! Superjolts. With a Synertek Superjolt CP110 manual and Tiny Basic + RAP (assembler) in ROM.

A good opportunity to update the 6530 and the Jolt SuperJolt pages. Better quality and more documents, more photos, ROMs dumped.

THE-RC 41523 CPU-4

CPU-4 is a 6502 SBC based upon the TIM 6530-004. Developed for teaching on the Technical University Eindhoven.
The only surviving part of the system is a 40 page Dutch manual.
Described are the function of TIM, Tiny Basic and Resident Assembler Program, same as the Jolt and Superjolt.

Dutch manual of RC41523 CPU-4

Some excerpts from the manual:

Known 6530 variants

6530-002 $1C00-$1FFF KIM-1 listing in KIM-1 Users manual
6530-003 $1800-$1BFF KIM-1 listing in KIM-1 Users manual
6530-004 $7000-$73FF TIM Terminal Monitor, see the TIM page
6530-005 According to this OSI appnote this is an unprogrammed version of the 6530 TIM
I have only seen ads for this part without further description of what this is.
It has the 16 I/O lines, 64 word RAM and the timer, which can generate an IRQ. One can assume the ROM is empty.

6530-006 Allied Leisure pinball version 1 (IC6)
6530-007 Allied Leisure pinball version 1 (IC3)
6530-008 Allied Leisure pinball version 1 (IC5)
6530-009 Allied Leisure pinball (IC5)
6530-010 Allied Leisure pinball (IC6)
6530-011 Allied Leisure / Fascination pinball (IC3)

6530-012 Gottlieb System 1 sound board (R3014-12)
6530-013 Gottlieb System 1 sound board (R3014-13)
6530-014 Gottlieb System 80 series sound board (R3016-11)
6530-016 Used in Gottlieb system 80/80A/80B sound boards

6530-024 Commodore Chessmate (based upon Peter Jenning’s MicroChess)

6530-241 MIOT in pinball machines
6530-243 MIOT in pinball machines

Commodore diskdrives ROM at $FC00-$FFFF

901466-01 6530-??? 2040 DOS 1.0 Shugart SA390 2040, 3040 and 4040
901466-02 6530-028 4040 DOS 1.2 Shugart SA390 2040, 3040 and 4040
901466-04 6530-034 8050 DOS 2.0 DOS 2.1 Shugart SA390
901483-02 6530-036 8050 DOS 2.5
901483-03 6530-038 8050 DOS 2.5 Micropolis 1006-II (8050)
901483-04 6530-039 8050 DOS 2.5 Tandon TM100-3M (8050)
901884-01 6530-040 8X50 DOS 2.7 Tandon TM100-3M (8050) Tandon TM100-4M (8250)
901885-01 6530-044 8X50 DOS 2.7 Micropolis ???
901885-04 6530-047 8X50 DOS 2.7 Micropolis 1006-II (8050) Micropolis 1006-IV (8250) Micropolis 1106-II (Safari, mit Garagentor, 8050) Micropolis 1106-IV (Safari, mit Garagentor, 8250)
901869-01 6530-048 DOS 2.7 M.P.I. 101SM (8050)M.P.I. 102?? (8250)
251256-02 6530-050 8250 DOS 2.7 Matsushita JU-570-2 (8250LP)
251257-02A 2716 DOS 2.7 Matsushita JU-570 (SFD-1001) Matsushita JU-570-2 (SFD-1001)
251474-01B 2716 DOS 2.7 Matsushita JU-570-2 (8250LP)

Replacing the 6530-002 and -003 in a KIM-1 has become quite easy. See this page on replacements with a 6532, some glue logic and a (E)EPROM.

The RRIOT in CBM disk drives are only different in the ROM contents The rest is as follows:

– Pin 18 is PB6 (no CS1).
– Pin 19 is CS2 (noPB5) .
– Pin 17 (PB7/IRQ) has no Pullup.
– ROM is in $FC00 bis $FFFF (RS0=0, CS1=X, CS2=1).
– RAM is in $0000 bis $003F (RS0=1, CS1=X, CS2=0, A9=,0 A8=0, A7=0, A6=0).
– I/O is on $0080 bis $00BF (RS0=1, CS1=X, CS2=0, A9=,0 A8=0, A7=1, A6=0).

Logic of addressing:

 	RS0	CS1	CS2	A9	A8	A7	A6
ROM	0	X	1	-	-	-	-
RAM	1	X	0	0	0	0	0
IO	1	X	0	0	0	1	0

Via an adapter board Commodore reused older 6530’s with new firmware by disabling the built in ROM and adding a 2716.
See Zimmers Commodore archive. Note that not just any 6530 can be used in this way, only the 6530’s from the Commodore diskdrives. A more general approach with a 6532 is described here.

Most if the information on this pages is also found on the pages of Martin Hoffman Vetter

RIOT 653X datasheets

Datasheets 6530

The 6530 was produced by most 6502 manufactures, from MOS Technology/Commodore SG to Rockwell and Synertek. All production datasheets that I have seen are identical, The oldest one is a preliminary MOS datasheet for the MCS6530, missing the ordering pages of the production version.

MOS Technology MCS6530 Memory IO Timer Array
Preliminary Data Sheet 1975
MOS Technology MCS6530 Memory IO Timer Array
Preliminary Data Sheet 1975-08
MOS Technology MCS6530 Memory IO Timer Array
Preliminary Data Sheet 1975
Commodore 6530 6520 datasheet
Commodore 6530 datasheet
MOS 6530 datasheet
> Commodore MOS 6530 datasheet
Rockwell r6530 RRIOT
Synertek sy6530


MOS 6532 RIOT Preliminary feb 1977
Commodore MOS 6532 RIOT
Commodore MOS 6532 RIOT
Rockwell R6532
6532 timer interrupt precautions
6532 timer interrupt precautions
Rockwell R6532 RAM IO Internal Timer Device (RIOT)
synertek sy6532

CMOS 6532

The 6532 exists in CMOS, I have only seen the California Micro Devices GSE 65SC32 variant.

Synertek 65C32 preliminary

Other RIOTs
In Rockwell databooks there are more RIOTs described. 6531, 6534. Never seen in the wild, a mention here and there of being used in pinball machines.
The timer/counter is a lot more capable, 16 bits etc.

R6531 ROM-RAM-I/O-Counter (RRIOC)
R6531 ROM-RAM-I/O-Counter (RRIOC)
R6531 ROM-RAM-I/O-Counter (RRIOC)
Rockwell R6534 ROM-IO-Counter (RIOC)

Me and my KIM-1

My first computer is a KIM-1. Still have it! A life changing experience!

This is the story of me and the KIM-1.

Philips educational kits.

As a young child, at age 12, I was introduced to electronics with the Philips electronic kits. First a Pionier crystal radio. Easy to build, good instruction manual. Lots of listening pleasure!.

Two years later I bought the Philips EE8 Electronic Engineer kit. Again nice builds (the 8 stands for 8 experiments), with a good manual. Since the manual covered the expansion to the EE20 for 20 experiments, I bought the parts myself one by one at Aurora Vijzelgracht, Amsterdam.
More on the Philips electronic kits.

Radio Bulletin

In 1978 I bought my first computer, a KIM-1. It turned out to be a Rockwell rebadged Rev F Mos Technology board.

The beginning of lots of fun, learning, member of the KIM gg Club and making and publishing in the dutch electronics magazine Radio Bulletin and the KIM Kenner.

In 2014 the big KIM-1 machine was finally taken down in parts, the following photos showed the end result as in 1985 after many years of tinkering.

The KIM-1 system ended as a real production system until 1985, mainly to write articles, all Radio Bulletin and KIM Club Magazine related work was done with this system.

My KIM-1 workplace in 1979, no video terminal, no printer, hand assembly

My workplace setup in 1982: KIM-1, dual cassette, tv monitor, H14 printer, ASCII keyboard

1984, VT100 as videoterminal, what a progress!

Then a CP/M machine took over (a Spectravideo X’Press 738) with the same VT100 as terminal.

  • KIM-1
  • 8K RAM  in system case
  • 32K RAM in expansion case
  • Two ACIA 6850 serial
  • A PIA/VIA card with two 6820 PIA’s
  • Parallel ASCII keyboard with home made logic circuit
  • Video Display 32×32 uppercase characters on an analog TV
  • Dual cassette tape system with motor control
  • MDCR digtal cassette system in second expansion case
  • Radio Grafisch Display in second expansion case
  • Heathkit H14 matrix pinter, serial with RTS handshake via bitbanging RIOT port
  • VT100 Digital Equipment Video display unit VT100
  • Boot tape to load device drivers and Micro Ade (extended to 8K)
  • MICRO ADE assembler/editor, used for program development and article authoring
  • Microsoft Basic KB9 (not used often, nice study material!)
  • Pascal-M compiler and interpreter (mainly development and experiments, not for production)

First the KIM-1, I still have it, in working condition, in my private museum. Changes still visible, are a red acryl cover over the LED displays, a capacitor moved to the back to make it flat enough to fit the case I made and some supports to have it lay stable and safe on a table.

Why a KIM-1?

In 1977 I was reading in the electronics magazines about the revolution taking place: 8 bit microprocessors!
During my study I encountered Digital Equipment machines, PDP-8 in the lab, PDP-11 in the Mathematic Computer Science department, a Minc in Medical Physics group, my major.
The electronics department where I was doing an intern not only introduced to digital electronics and I helped them to introduce the Z80 to the instruments designed for laboratory experiments.
I learned assembler quickly, PDP-11 was a dream come true, the Z80 a bit of a nightmare but you could do so much with effort.

At the same time I started to write for the magazine Radio Bulletin, simple analog and digital circuits and continued to be an editor until 1987. I met Dick de Boer who was writing his famous Microprocessor articles and introduced the KIM-1 to the Dutch electronic engineers. So a KIM-1 with the very attractive 6502 was the logical choice for my first microprocessor system.

First case: memory, connectors, power supply

A KIM-1 itself was fun to learn with, but it quickly needed more; a permanent power supply, protection, easy to access connectors and interfaces for  a bus to have  more memory.
So the case seen in the next figure was built:

Power hungry, so lots of lineair power supplies with large cooling.

The first case I built from alu profiles contained the KIM-1, a backplane for 6 memory boards, a lot of power supplies (lineair, so heat was a problem!), a patch panel to access the expansion connector, cassette I/O, serial interface and various switches.

PCBs handmade, double sided!

Memory 2K RAM Card, BEM Bus Brutech Variant made by Hans Otten
Memory boards were made myself by drawing with Edding ink on the blank PCB, etching and drilling. Filled with 2102 RAM IC’s for 1K per board, it filled lower RAM of the KIM-1 $0400 – $13FF. The bus is a 31 pin DIN connector, based upon the BEM (Brutech) bus.

I bought two of this deck from Radio Service Twenthe, Den Haag, fascinating electroncis dump store!

The next thing I built was a video display unit. All TTL 74XX logic IC’s, a 2513 character generator, a AY-5-1013 character generator, an ASCII keyboard, display on TV 32×32 characters uppercase. RS232 input/output to the KIM-1.
On top of the VDU a dual cassette deck is shown. From the famous Dutch dump shop Radio Service Twente two audio cassette decks were bought, some audio amplifiers and power supply added, and a remote control circuit via a 6532 GPIO line (standard as in Micro Ade). Served me well for many years, in 2014 the decks strings were dried out and crumbled after many years of not being used.

Next was a real expansion cabinet with a long backplane for 32K memory with 8x 4K RAM card, 2114 based, Designed by me, published in Radio Bulletin and sold by Visser Assembling Electronics. BEM bus compatible.

4K SRAM card

4K SRAM card, Radio Bulletin September 1979 part 1  part 2

Production 4K RAM card

Prototype 4K RAM card, also hand drawn on the PCB!

In the expansion cabinet three slots were added for I/O. Two cards were designed by me and published in Radio Bulletin: an ACIA card for two 6850 Motorola ICs, and a PIA card for two PIAs, 6522 or 6520 or 6820 or 6821. I never used more than one ACIA and one PIA card. Shown are the prototype cards, in the article production quality PCBs were used.

PIA and VIA card design by Hans Otten June 1984 Radio Bulletin

ACIA Motorola 6850 by Hans Otten, 1983 Radio Bulletin

On one of the ACIAs a VT100 Digital Equipment terminal was connected, taking over from the bit banged serial interface and the homebuilt video display. ON the other ACIA a Heathkit H14 matrix printer was added, a mediocre but adequate printer.

Together with Micro Ade as assembler and editor, the dual cassette deck, 40K RAM In total, this was a nice machine! Until 1987, when I bought the Spectravideo X’Press 738 MSX and CP/M system, used for all my publishing activities.

A third expansion cabinet was built around 1983. It was driven by the PIA’s, the Radio Bulletin Grafisch Display was inside the cabinet, along with two MDCR Philips Digital cassette recorders, alo published in Radio Bulletin. The speed difference between Hypertape audio cassettes and 2400 baud MDCR speed was not that impressive.

Dirk Dral

EPROM card (Dirk Dral)


Christian Ortner (mister-freeze at the VzEkC e. V. forum build a SBC with expansion around a TIM IC.
Here is his projects description of the TIM-1 SBC. TIM-1 OverviewSchematic, images, hex listing of Lunar Lander!