Archive for the ‘Gepard’ Category

Gepard – Part Seven: The Gepard Company

January 6, 2020

As with many startup companies, the history of the Gepard company is very intense, but unlike many unsuccessful startups, it is both rather short *and* produced tangible results in time.

So, let’s start at the beginning.

It is the year 1983. The computers in the consumer market are mainly 8-bit computers. It is already clear at this point that the Next Big Thing will be 16-bit computers, but in Germany you can buy 16-bit computers only as expensive, professional computers. Examples for these models are:

  • the HP 9816 (starting at $3895 or about DM 14,000)
  • the Tandy TRS 80 Model 16 (admittedly more a semi-professional machine) at about DM 17,500
  • the Fortune 32:16 at DM 25,000

In the US, there is the “Dtack Grounded” single board computer sporting a Motorola 68000 CPU at the maximally possible 12 MHz. It uses SRAM in order to use this speed, but the board does not offer too much more. The people behind this computer also publish a newsletter of the same name which is informing its potential customership about the current developments regarding this board and the industry.

Having this in mind, a group of friends aims at founding a computer company that targets a computer these group would like to buy themselves. The assumption behind this strategy is that such a computer should meet the needs of a market of similar minded people. The requirements of this computers would be:

  • a Motorola 68000 CPU
  • modular design for maximal flexibility
  • initially designed as an add-on for an Apple II computer because:
    • the friends are Apple fans
    • this approach has the advantage of not needing to develop own UI and storage hardware from the start
    • this allows for a cheaper price for the first product

This company, the “Gepard Computer GmbH & Co. KG” is founded in Oldenburg, Germany in August 1984. The initial founders are:

  • Thomas Schumann
  • Herman Spille
  • Klaus Onnen

Later on, two more founders join:

  • Meinolf Schneider (nowadays: Amekudzi)
  • Bernd Heyer

In order to finance the company, each founder has to contribute DM 40,000. More money is contributed by an investor. The inital round of financing sums up to DM 410,000. A second round adds additional DM 180,000.

In the spirit of Dtack Grounded, also Gepard published a periodical newsletter on paper even before the actual company was started. It informed potential customers and interested parties about the current and upcoming state of Gepard developments, it provided information in different, related topics, and it dissed the competion. The newsletter was completely free. It was published from October 1983 to March 1986 in 12 issues of typically 12 A5 pages in an edition of 500 copies each. The newsletter lead to several contacts, not least it was read by a contact of the later investor of Gepard.

Development of the hardware starts already in 1983. The founders and some first employees design three cards (CPU, RAM, Apple II Interface) for the Gepard, a backplane, an Apple II card (which connects to the Interface card), the Modula-2 compiler, the operating system (GDOS), and the software that runs on the Apple II. They have the PCBs then produced locally (in Oldenburg), buy components, and populate and solder the PCBs themselves. A first run of 30 sets is produced and in 1984 the first sets can be sold to the people who had registered via the newsletter.


Marketing-wise, Gepard was not very active, but tried to get the most out of its limited effort. The main marketing channel was the Apple User Group Europe (AUGE). So it distributed the newsletter generously via AUGE channels. In the newsletter readers could register an option on a Gepard for free. 30 options were registered and 3/4 of the options were resulting in purchases. AUGE was divided in regional chapters, and in many of those chapters there was one Gepard owner, so there was always one to present a Gepard or who could be asked for opinions. As a consequence, and because of a 10% commission Gepards are mainly sold by word of mouth and by existing customers. There was also an article in the AUGE magazine (8/84) on the Gepard. Articles on the Gepard are very rare, not least because at that time, journals prefer promoting their own computer projects than reporting on a new computer with a very small customerbase. Nevertheless, Gepard also runs (small) ads in the most important computer journals. Finally, Gepard is represented with (probably very small) booths both at the Hannover Messe 1986 and at the Orgatechnik 1986.

In 1984, Apple releases the first Macintosh, also a 68000-based computer. Fortunately for Gepard, although the Mac has a mouse and a GUI, and is sold complete in a neat, compact package, it is more expensive (at DM 10,000), and it is (at 8 MHz) slower than the Gepard. It is also by and large not expandable. As also the typical customer of a Mac and a Gepard differ substantially, the Mac is no threat to the Gepard.

Until 1985 Gepard had 70% private and 30% professional customers. In the fall of 1985 Atari starts selling a new model, the Atari ST for an unrivaled low price (~DM 3,000 including floppy disk drive, monitor, mouse, and GUI) and basically ends sales of Gepards to private customers. The Gepard company does not know how to react to this competition, has not finalized all of its developments and is out of money. Eventually, 1986, the company files for bancruptcy.

In hindsight, Thomas Schumann, the former CEO of Gepard, thinks that it would probably have been possible to save the company if the management would have had more experience, and if it would have moved its focus to professional customers, offering a Unix-like operating system. After having found that the later 68020 version of the Gepard was quite unique at least on the German market for its price, I agree.

After Gepard went bust, one of the original founders, Hermann Spille founds his own company, HS Computer, to continue the Gepard business. He continues selling hard- and software from the Gepard catalogue, but also develops and sells new hardware. The most important development activity is the finalisation of the 68020 card and the development of the second version of this card. Other hardware includes:

  • a Z80 card
  • an EPROM burner

Apart from HS Computer, there are a whole number of small projects starting in the aftermath of Gepard:

  • ports of OS-9, PC DOS 2.1/GemDos, Eumel/Elan are started or at least proposed
  • version 1.4 of GDOS is finalized by Thomas Tempelmann
  • version 2.0 of GDOS is written by Harald Hellmann
  • an “Atari ST” graphics card is developed that can be connected to an Atari monitor

But eventually, over time, the Gepard business trickles off and HS Computer is liquidated in 2009.

Ok, so, here you have it. My collected findings about the German Gepard computer. I hope you liked it. It took me a long time to collect, analyse, and write, but it was fun, it was new, and it was basically never documented before (especially in English).

Gepard – Part Six: The Software

January 1, 2020

Let’s talk about the software in the order in which it was developed. We therefore start at the beginning (in Gepard terms): the Modula-2 compiler.


One cannot talk about the Gepard story without mentioning its Modula-2. Following the Zeitgeist (and Apple) not only should the operating system of the Gepard be written in Modula-2, but this computer language was also foreseen as the system language, the main application language, and the shell/batch language. This meant e.g. that all hardware was accessible to Modula-2 languages, by providing corresponding libraries.

The Modula-2 compiler was initially written by Jürgen Müller (who did not have much experience in this matter) directly in Assembler. The development started as a cross-assembler project on an Apple II. As soon as enough developer systems were produced, the development was moved to a Gepard itself, and as soon as no Apple II (or C64) was needed anymore, everything was done on the Gepard itself. As a result of being developed in Assembler, the compiler was very fast at compiling code (one Gepard manager believe it to be the fastest M2 compiler at that time in the world). As a result of the main programmer being not that experienced in that area the compiled code was not that fast (although the comparison of the Gepard Modula-2 to any Apple II compiler went of course very well for the Gepard as proven by the original comparison from 1985(?) below).


source: 68000=news Nr. 6

Users of the Gepard Modula-2 also often mentioned the completeness of the compiler positively. Being the main system language, it even featured an inline assembler.

Jürgen Müller received a royalty of 22.50 DM per Gepard for the compiler.

Later on, the Gepard M2 was ported to the Atari ST under the name “Megamax Modula-2” by Thomas Tempelmann. It was then distributed by “Application Systems Heidelberg”, which was funded later on by another former employee of Gepard. The initial version was mainly a pure port of the original Gepard version, later issues had improved features. The lower execution speed of the compiled code was also mentioned in comparative reviews of different Atari ST Modula-2 compilers.

However, the Modula-2 compiler was certainly the main reason to buy a Gepard before OS/9, because there was simply no other language you could use (except Assembler) nor any standard binary format of a program that could be executed.

The (original) Operating System: GDOS

The focus on a programming supporting software system continues on the User Interface side: it is a clone of the UCSD Pascal UI. It is all text, no mouse pointer nor windows in sight. All you have are a fixed set of commands that you reach by typing a single key. Some of the commands are displayed in the first line of the screen. If you branch into one command (which is an application on the top level), you have another set of sub command, some of which are displayed on the top.

Some of thes applications on the UI level are: Editor, Compiler, Monitor, Filer (a program that can do things with files).


This is a strange version “1.4cv”

One could argue that it would have been better to use a standard Operating System, but apart from Unix (which basically required a harddisk) there was not really one. The was CP/M-68k, but this was hardly standard and would have offered only a few advantages while being costly.

However, the lack of Unix was probably *the* problem that prevented the success of Gepards in the professional area after the Atari St and the Amiga had killed the private market for the Gepard. If it would have offered Unix, a Gepard would have been probably a cheaper alternative to “professional” 68000 computers, especially after having finished the development of the 68020 cards.

During the time of the Gepard company, GDOS was developed up to version 1.3*. Version 1.4 was finished after the Gepard company went bust. It was developed by Thomas Tempelmann, who tried to convince Gepard users to pay him some money for the version because the development was no longer financed by Gepard. It is not completely clear to me whether 1.4 was the last “official” version of GDOS because I have a version 1.5 from the floppy disk remainders owned by Jürgen Müller, who was obviously part of the special interest group GDOS maintenance who is mentioned on the splash screen of version 1.5.

A much more capable version of GDOS was always in the planning, even at the time of the Gepard company. A corresponding, much improved version of GDOS was later on published as “GDOS 2.0″ (and later on called OS/Science”) offering e.g. multitasking, different fonts, etc. However, as far as I can tell, this was never delivered with later Gepards, but needed to be bought as a separate software for DM 400.

Application Software

There wasn’t much application software as far as I can tell.

There was Gepard’s own editor (GepStar, a WordStar-like program) and Gepard’s own spread sheet program, GepCalc. Initially sold separately, it was later on bundled with GDOS 2.0.

There was Gepard’s own PCB layout program, PlaTool, which Gepard used itself to design new cards.

Then, there was a small catalogue of little tools like GepTerm, a terminal program, a disk with utilities, one with test tools, disks with Modula-2 libraries for mice and graphic tablets, the GDC graphics, and the graphics of the 80-characters-card. There was a small sampler program, and two disks with samples.

For GDOS, GepStar, GepCalc, and the Boot ROM images, you could also get the source code.

The other Operating System: OS-9

OS-9 is a Unix-like multi-user, multi-tasking operating system originally developed for the Motorola 6809 processor by a company called Microware Systems Corporation. It was originally developed from 1979 as the operating system for the BASIC09 project fundedy by Motorola. At that time it was used mainly for TRS-80 Color Computers, and Dragon computers (requiring a floppy disk drive). In 1983, OS-9 was ported to the Motorola 68000 CPU.

In contrast to most operating systems, OS-9 was sold mainly as a 3rd-party-product that needed to be purchased by the users. Therefore, also the Gepard version of OS-9 was sold for about DM 750 from about the end of 1986 onwards. At Gepard times it had a small but active community including an own newsletter. On the Gepard, OS-9 uses its own file system and cannot be copied by GDOS tools.

You can still get OS-9 for many computers today.

Even if you cannot copy OS-9 using GDOS, you can copy it using OS-9. First, boot OS-9. As the user name, use an empty string, i.e. just hit ENTER. Now, you can format a new floppy disk with format /d0 (if you want to use the first drive) or format /d1 (for the second drive). Using the backup command, you can copy disks. For a cheat sheet of OS-9 commands, look onto the last page of this file.

Software, that did not really make it

CP/M 68k

This actually appears in the 1986 price list including a C compiler for DM 1225. I know someone who claims that he actually tried it. However, I do not know anybody who claims to have actually used it. Technically, it would not have been impossible to actually port it. Most probably, the price was basically determined by the license fee and it offered not that much of a benefit compared to GDOS.

PC DOS 2.1/GemDos

In 1986, in the aftermath of Gepard Computer GmbH going bust, someone asked for subscriptions to a project that wanted to port GemDos to the Gepard. It would include PC DOS 2.1 and the GEM Desktop and would cost DM 499.- If 100 users would subscribe, they would buy the license from Digital Research and start porting the software. I never read anything about this project again, so probably the 100 subscriptions never happened. Also, it seems a little bit like a stretch to port PC DOS to the 68000.


Elan (Education Language) is a programming language that was developed in 1976 in Germany. The Operating System to run it was called Eumel. Like the GemDos porting project, this was an attempt by an individual to open the Gepard to other software worlds. Like GDOS was written in Modula-2, Eumel was mostly written in Elan. The price for a multi-user version would have been DM 750.-, but like the GemDos port, this project seems to have never materialised.

Gepard – Part Five e): The Hardware: GDC Graphics

December 15, 2019

The Gepard 80-characters card is able to display also some monochrome graphics, but if you wanted color you had to buy the GDC graphics solution. This solution is rather unique in that it is a modular graphics subsystem centered around the NEC 7220 chip, which is a marvel on its own. But let’s start at the beginning.

A GDC graphics subsystem consists of one Video card and 1 to 8(!) GDC cards. The GDC cards are “daughter-boarded” (or to another GDC card) to the Video card, and only the Video card connects to the Gepard bus, making it a rather bulky PCB block. You can see this on my GDC block consisting of 3 GDC cards on top of the Video card.


Each Video card cost around 300€ and each GDC card around 500€. This means the maximum configuration cost 4300€, that’s more than an entire (text-capable) Gepard computer…

The Video card has pin header connections for:

  • a monochrome Composite monitor signal (the same as from the 80-characters card)
  • an analog RGB monitor

The GDC card each have a NEC 7220 graphics processor and 128 kB RAM.

If there are more than one GDC card, the cards can share the workload by being responsible only for a part of the color information each.

For example, if you have 8 bits of color information per pixel, you can share it amongst 1, 2, 4 or 8 GDC cards. As a positive side effect you can have higher resolutions as each card has to work less on a single pixel in the restriction imposed by the time a single frame needs to be created (which is given by the time the CRT tube needs to display the single frame).

Depending on the RAM need of a single frame, the number of GDC cards, and some other restrictions, you can have more than a single frame (up to 16) drawn in parallel (then simply switching to another part of the RAM).

You can have up to 256 colors out of a palette of either 2^12 or 2^18 colors (the manual and the price list differ in this point).

The highest achievable resolution seems to be 1024×102 pixels.

It is not possible for me to list here all possible resolutions, color depths, and number of parallel screens as this depends on:

  • the number of GDC cards
  • the type of monitor interface used
  • the jumper configuration on the GDC cards

Also, not all combinations are possible.

The NEC 7220 chip is probably the first integrated “GPU” chip. It was released in 1982 and had the following features:

  • DMA-capable
  • own memory control
  • own command set: lines, circles, arcs, rectangles, characters
  • can address up to 512 kb RAM
  • max. resoution: 2048×2048 pixels
  • can use a lightpen directly

Its importance can also be seen from the fact that Intel licensed the design and produced it under the Intel 82720 designation. Which in turn triggered the Soviet block U82720 clone.

This graphics architecture has the advantage of being

  • very scalable
  • easy to incrementally extend

but also to be

  • very expensive (in 1985, my 3-GDC-card block is more expensive than an entire Atari ST system a year later on)

Therefore, GDC graphics seem to be rather scarce. Out of the 6 Gepards whose configuration I know only mine has GDC graphics, the rest has 80-characters cards.

Also, there are hardly any other computer models based on NEC 7220 graphics that have more than one such chip. The DEC Rainbow 100 (graphics option), Epson QX-10, QX-16, Tulip System-1, EC 1834, A7150, as well as the Number Nine Revolution 512 family of graphics cards all had one NEC 7220 (or equivalent) chip. Only the NEC PC-9801 and the NEC APC family had two, supported by 256 kB RAM.

In later years, GDC cards had 512 kB RAM each.

Gepard – Part Five d): The Hardware, Misc. Topics

December 2, 2019

To conclude the hardware parts, here some short remarks on various
“hardware”-related topics.


Serial Numbers
Easy topic. There weren’t any. Neither on the case nor on the cards. However, some cards have a paper sticker with a date on it.

Card Versions
My above remarks on the different cards might have give you the impression that there was only one version of every card. Well, there wasn’t. Some cards have even version numbers on the PCB. See the above picture. CPU card V1.3. Sticker with a “18.11.(19)85” date. Hmm, I could have mentioned that Gepard designed the PCBs (later on with a program on a Gepard), a company in Oldenburg, Germany (where Gepard was located) produced the (naked) Gepards, and Gepard itself populated them. Quite short turnaround time I would assume, but neither the fastest nor the cheapest way. Quality, local production, though. These were the times where assembling stuff in East Asia was not the fast, cheap, (sometimes) quality way to go for every company.


The Manual
No Gepard system was complete without the (up to) 650-page custom-made A5 ring binder. “It was not complete” is not a phrase. As the operating system, the hardware, and the system programs were all completely proprietary, this was the only document that described them. The Modula-2 compiler was near-standard, but not completely, so you also needed a description of the details (e.g. in the 100 page annex). For good measure, it also contained a 144-page introduction into Modula-2 (which made sense as this was exactly the audience that would buy a Gepard). A description of the card hardware (incl. block diagram, population plan, pins and jumpers as well as the occasional Assembler code) allowed the user to use and modify the hardware. The manual was completed by a description of GDOS (the operating system), the “Filer”, and the “Monitor” programs as well as a 100-page description of the Motorola 68000 CPU. Everything you need in a pre-Internet age.

Oh, yes, all documentation is German only 🙂 (well, the nouns are often English as is usual in technical German). You can find two version of the manual in the electronic resources post.

Gepard – Part Five c): The Hardware, Phase 3

November 25, 2019

After the Gepard company went bust, one of the founders, Hermann Spille, founded HS Computer and continued providing Gepard hard- and software and even developing further cards. In this last phase, the 68020 cards were finished and put on the market. In this phase, most of the cards from the 2nd phase were still available. HS Computer was liquidated in 2009. Afterwards, no new Gepard component development or distribution seems to have taken place.

Third Phase: 1987: the 32-bit era


68020 cards

There were two variants of this card. In April 1987 the first version appears. It sports a Motorola 68020 with 12.5 MHz, offers a socket for a 68881 FPU, and 128 kB SRAM. The problem with the Gepard architecture and 32 bit CPUs is that the used proprietary bus is a 16 bit bus providing mainly the signals of the 16 bit 68000 CPU. A 32 bit CPU needs a 32 bit bus if you want to connect CPU and RAM at full speed. In a backplane-based system like the Gepard CPU and RAM reside on different cards. Now, unfortunately, you cannot change the bus in a backplane-based system because you would have to change a lot of hardware and still have the problem of backwards compatibility with the old 16 bit cards. So, the typical solution, also used here, is to put (some) RAM on the CPU card (where you can have 32 bit connections), and use the system bus for the rest of the system. The first version provides only a small amount of on-CPU-card RAM (128 kB) and tries to mitigate this small amount by using a faster RAM variant, namely SRAM. The bulk of the RAM is still residing in the separate RAM cards, connected by only 16 bits, but by caching memory in the SRAM now not every RAM access needs to pass the 16 bit bottleneck. Although not backplane-based system, the same problem and solution occurred also for the Amiga 3000 and Atari TT. They both sport the legacy 16 bit architecture of the Amiga and Atari ST, respectively. This means that both new systems basically contain an old system, but now have a 32 bit CPU. That’s why in both systems you have now two different types of RAM: old, 16 bit-connected RAM, and new 32 bit “Fast” RAM connected directly to the CPU.

The second version (in DEcember of 1987) of this card uses 16.5 MHz, has also a 68881 socket, and sports now an own 32 bit socket for a daughter memory card. At the same time, a 4 MB (D)RAM card is offered for this socket. This allows now to access all memory with 32 bit.

In the research of the Gepard history it occurred to me that probably from 1987 the 68020 Gepards were the cheapest 32 bit systems in Germany until the appearance of the Amiga 3000 and the Atari TT in 1990.


Z80 card (“HD 64180 – Karte”)

This card contains a Z80-compatible HD 64180 processor that runs at 8 MHz. It provides also 256 kB of RAM. Additionally, it features a Centronics printer port and two serial ports. It is delivered with an LDOS called operating system that is compatible with CPM 80 V3.0.


EPROM Burner

This card allows to program two EPROMs at the same time. This card has a cable that connects to a small external box with two EPROM sockets. The needed software is delivered with the card.


“Atari” Graphics card
This graphics card was developed by a company that two of the other founders of Gepard founded. It offeres basically the monochrome graphics capabilities of the Atari ST having a resolution of 640*400 pixels black and white and have an interface where the 70 Hz Atari monitor (e.g. the SM 124) can be connected to. This card can also be used for generating text output instead of the 80-characters card.

Gepard – Part Five b): The Hardware, Phase 2

November 21, 2019

In this phase, the Gepard becomes a self-contained, autonomous system as all necessary components are available from the Gepard manufacturer. This means text and graphics output, keyboard input, and floppy disk drives. The cards of the First Phase get improved or have successors, and new functionality is added in the form of cards. The second phase is coming to an end when the Gepard Computer GmbH closes.

Second Phase: 1984 – 1986, Gepards as autonomous computers


CPU cards
Now a Motorola 68010 card (also at 10 MHz) is available, replacing the original 68000 card (at least in the Price List 1/86, the old CPU card is no longer available).


RAM cards
The first card was a 128 kB DRAM card. It is soon followed by a 512 kB DRAM card, and then by a 1MB one. There is not much to say about these cards apart from you can have up to 7 128 kB cards, or up to 2 512 kB cards, or multiple 1MB cards plus one 512 kB card.


80 Characters card
This is the card used in text Gepards to display text. It can display (surprise, surprise) 80 by 25 characters. Each character consists of a 8 x 11 pixel grid. It can display four different, freely programmable fonts (a 128 charachters each) at the same time. The program to define these fonts is even contained in the Operating System. Additionally, it can display (equally monochromous) graphics with a 320 x 192 pixels resolution. This card can be used in parallel to a GDC graphics card. The standard output interface is a (Y) component cinch plug. The card can serve monitors with a line frequency of 15.75 KHz. The monitor options from the catalogue were a 12″ Taxan KX 1201 or Taxan KX 1203. Recently I had no problems displaying the output on a quite recent Sony 4K TV and an older noname CRT TV.

GDC Graphics card
The GDC graphics card (or, rather, subsystem) is architecturally a marvellous thing, but way too expensive. As it deserves an own blog entry, I will give it one :-).



Floppy Disk system
Such a system consists of a Floppy Controller card and one or two, theoretically even up to four floppy disk drives. The controller card can control either two standard 3.5″ floppy drives or two 5.25″ ones, or up to four “Gepard” 3.5″ floppy disk drives. The data rate can be selected between 250 and 500 kbps. Drives can have up to 2 times 80 tracks. Software-wise a track is divided into 5 sectors of 1024 bytes each. This results in 800 kB disks capacity.
The “Gepard” drives are Sony MP-F52W models that have a data rate of 500 kbps, something the early Gepard newsletters are really excited about. In the first price list (1/85) a full height Sony drive is depicted, a year later the drive is half height. The controller card has two potentiometers with which the Read Pulse Width and the Read Pulse Width can be adjusted.


Multi-Function card
This cards contains a keyboard interface, a battery-buffered real-time clock, two joystick ports, a programable timer, a PIA, an analogue multiplexer, two D/A converters, and one A/D converter. It was the standard means to connect a keyboard, so these cards are often contained in 2nd Phase Gepards. The keyboard interface is a 5-prong (big) DIN connector. The standard keyboard was a Marquardt type 703 or 704 with a Gepard logo. Later on there was a cheaper option, the “AFC Operator” keyboard. The Multi-Function card was also the audio source and typically the (mono) loudspeaker contained in the computer case connected to the sum of the two D/A outputs. There was no sound chip, so one had to prepare the audio data digitally so it could be put to the D/A converters. There was a program for the Gepard that could play out sample libraries using this mechanism.


Parallel/Serial cards
The standard way to connect to a printer was the Parallel-Serial card. It provided two Centronics parallel interfaces and two RS232 serial interfaces. The card even came with a Centronics cable. Additionaly, there was also an 8*RS232c card. It had a massive 50-pin Sub-D jack which provided the 6 signals for the 8 connections.


This card has 8 sockets for SRAMs or EPROMS. The advantage of SRAMs is the faster access speed, the disadvantage the higher price. You can mix SRAM and EPROM, but you have to always use pairs of chips. EPROMS provide Read-only memory that is available without having to read it from a floppy disk.

Complete Kits
Also in this phase the kits from the first phase are still available. Additionally, there is now also the C64 version of the Apple II system. Then, there are two new kits. The first kit is the “Text Packet”: a complete Gepard system complete with case, power supply, keyboard, 80 characters card, floppy controller card, one 3.5″ floppy disk drive, a multi-function card, and the elements from the Apple II kit (except the Apple II card). The RAM card is 512 kB, and the I/O card is used as a Boot ROM card. The Text Packet (or variations of it) seems to be the most frequent Second Phase Gepard. And, finally, there is the “Graphics Packet”. It is a Text Packet kit plus a 14″ monochrome monitor and a GDC graphics card as well as a parallel/serial card. The RAM card has now a full MB.

Other cards
There are also a few other cards in the catalogue 1/86:

  • an 8-channel A/D and D/A converter card with 10 bit resolution
  • an 80-channel card with 40 output and 40 input TTL channels
  • a mouse/track ball card with two 9 pin interfaces
  • two MIDI interface cards. One with one MIDI input and one output interface, and one with 8(!) MIDI outputs and 8 MIDI inputs. The latter card even includes six serial ports
  • an IEEE-488 interface card

Gepard – Part Five a): The Hardware, Phase 1

November 13, 2019

As I said the Gepard is a modular computer. Modular here means modular like in the early days of private computers: you have a case with a backplane, and everything else, from the CPU to the RAM, comes in single cards that can be inserted into the case. This is a photo of a typical Gepard configuration from the back. Yes, there are no card covers or handles, this is the factory view:


Every Gepard computer had at least three types of cards in it: CPU, RAM, and Boot ROMs.

First Phase: 1984-1986, Gepards using Apple IIs or C64 as terminals and drives

In this phase, a Gepard had to connect to an Apple II or (later) to a C64 as there were no graphics cards, keyboard interfaces, or floppy disk interfaces yet. Instead, a Gepard I/O card connected to an Apple II card (or, later on, the user port of a C64) via a ribbon cable. The Apple II (or …) provided the keyboard, the display, and the floppy disk drive. Software, therefore, had to be booted from an Apple II floppy disk. There was some boot ROM on the I/O card specific to the computer model (Apple II or C64) it booted from. A program on the Apple II provided the necessary support to the entire operation.

The Gepard bus has the mechanical format of the ECB Bus (96 pins in 3 rows), but has a proprietary assignment of signals. It is a 16-bit bus basically giving you the signals of the Motorola 68000 CPU.

The hardware from the first phase could also be used in later phases.


The backplane has 16 slots, the left 9 ones are quite close to each other while the right 7 are spaced further apart. One slot (the leftmost one) is used by the terminator card.

Terminator Card
The terminator card terminates all bus signals.

The case is a very rugged, heavy, modular steel sheet thing. There is place in the front for the power supply (on the left if you look from the front), and for up to 2 floppy disk drives (on the right). The back half of the case contains the backplane, and the space for the cards. Each card can be inserted on two plastic rails, one on the top and one on the bottom.

The thick front plate has the power switch on the left. The front plate has no inscription. Sometimes, there is a “Gepard” sticker on the top left side. Later front plate issues can have either a lock on the bottom left side or a keyboard interface in the bottom right.

The case has a timeless sandish (the brochure calls it “light ivory” like the typical taxis in Germany) color with brown bezels at the front and at the back. The middle stripe along the sides is of the same brown color.

Typically, there is no back plate. Normally, you see the single cards in the back directly.

The front feet can be raised, giving it the feel of a measurement device.

Power Supply (NMC 101 S)
Input: 220V, 50 Hz using a German “Schuko” plug
Output: 5 V/6A, 12V/2A, -12V/1A
There is a quite quiet fan cooling the power supply.


CPU Card
The first CPU card sports a Motorola 68000 with 10 MHz. Remember that in 1984 Macintosh has only 7.8 MHz, 1986 an Atari ST has 8 Mhz, and the Amiga has 7.2 MHz…
All Gepard CPU cards have a reset button.


RAM card
There is a 128 kB DRAM card capable of running at 8MHz (-5%). You can have up to 7 of these cards in a Gepard.


I/O Card
The is the Gepard end of the connection to an Apple II. It contains 2 boot EPROMS and an interface for a cable to the Apple II card.

Apple II card
This is the Apple II end of the connection to the Gepard. The connection is done via a ribbon cable and is an 8-bit bi-directional bus.

Complete Kits
A first phase Gepard kit either consisted of a backplane, terminator card, CPU card, RAM card, I/O card, and the Apple II card, or it included also a case and a power supply.

Gepard – Part Four: Known Gepard Computers

November 10, 2019

As there aren’t a lot of Gepard computers to start with and as I meet quite some of them I thought it might make sense to have a public directory of known Gepards. As not all of the owners (well, hardly any of them) have given me permission to do so, I’ll exclude personal details except the city and the configuration if known to me

City Configuration URL
Stuttgart Phase 1 + 3 GDC graphics
near Stuttgart Phase 1
Hamburg Text Gepard Phase 2
Michelstadt 68020, 128kB Text Gepard
Clausthal-Zellerfeld 68020, 4MB, Text Gepard
Mutlangen ???
Mutlangen ???
Schöneberg Text Gepard?
Leimen ???
Kiel (KPR) 68020-Boot, SCSI-B-Card, FG-Card, … , GDOS 1.52c

If you want to be on the list, send me photos of your Gepard computer.

Gepard – Part Three: Operating Gepards Today

November 10, 2019


You can display something only if you have either a 80-Characters card (80-Zeichen-Karte) or a GDC graphics card. Gepards that connect to an Apple II or C64 get their output on their Apple II or C64 screen.

Both cards can connect at least to a single component (Y) output, often as a cinch plug, monochrome only. Fortunately, component-in can be found even today in high-quality LCD displays such as some TVs or computer displays. Component means YPbPr (or, to be more exact, the single Y plug of this interface), not RCA RGB nor anything you can get out of a VGA, DVI, oder HDMI interface.

The original monitors were black/green CRTs with a single component interface. If you have one of them, use them if they still work.


Tricky. The Gepard uses a keyboard with a standard serial interface. As far as I know, these are very hard to come by these days. I don’t think that any PC keyboard can be used.

However, the advantage of using a standard serial interface is that you should be able to use any terminal or computer with a terminal program. The plug is a 5-prong “DIN” interface. Pin 1 is Data In, Pin 2 is Ground, Pin 3 is Buffer Full, Pin 4 is +5V. If “Buffer Full” is logically 1, the Gepard can receive a new character.
The serial interface uses: 1200 bps, 8 bits data width, 1 stop bit, Even Parity

Operating System/ Software

This is something I can help with as long as you can use 3.5″ Floppy Disks. Simply email me and let’s see what I can copy.

Missing/Additional cards

You’re out of luck. Curently, I do not know any source for new cards. Ebay is always a possibility, but I have only once seen a Gepard on Ebay, and it was mine afterwards 🙂 Single cards are probably even more scarce, especially as it is hard to identify them.

Gepard – Part Two: My digital resources

November 5, 2019

I decided to start with my digital resources for download first, because it might interest some people. So, here are scanned price lists, newsletters, manuals and the like. Unfortunately for some, they are all written in German.

Price lists



(1985) Manual 4.0

(1986) Manual 4.1