Sord M5 Pro

February 21, 2021
Sord M5 PRO

Recently, I bought a quite rare Japanese homecomputer at Ebay. It is the M5 Pro variant of the less rare (but still rare) Sord M5 computer. As the M5 was sold also in Europe, there is some information available on it. However, the M5 Pro was sold only in Japan, so this post focuses on the differences of the M5 Pro to the M5. As we will see, we can get rid of some misconceptions that have been made on the M5 Pro and Jr.

Sord Computer Systems was founded on 15 April 1970 by Takayoshi Shiina. In its first ten years it had become one of Japan’s fastest growing firms thanks to its success selling business micros on its home turf. The word Sord was derived from ‘SOftware haRDware’.

In 1982, Sord introduced its homecomputer model “M5”. It was meant to be mainly used as a games console. Therefore, it featured two joystick ports, only 4 kB of RAM, 4-channel audio, 32 sprites, and a cartridge slot. Also typically for game machines, the Basic was not built-in, but was delivered as a cartridge. Even more revealing is that the delivered Basic, Basic-I (I for Integer) did not feature floating point numbers or graphics commands. If you wanted these features, you’d need a Basic-F, or a Basic-G cartridge, respectively. The design of the case was very slick, and the PCB design and its build was high-quality and clean. The machine contained a dedicated graphics and audio chip and used Static RAMs. The keyboard was of a ZX Spectrum quality (because, again, this is not a serious business machine, and a 4 kB Basic program can also be entered by a lower quality keyboard). The M5 was introduced in other markets in 1983 (see the “The Register” article in the references for an account of the (lack of) success on the British market). There are also “CGL” branded M5s because CGL was the distributor of Sord in the UK.

Because the M5 was not a success, subsequent M5 models were only released in Japan, and not much is known about them. When we look at what we find on some popular web pages about the M5 Pro and M5 Jr., we find:

  • “[…] M5 Turbo, a faster version with “at least” 64KB of Ram […]. The M5 Turbo […] appear to have been released in Japan – as the M5 Pro […]” (The Register)
  • “M5 Pro […] were released with a built-in power supply unit (and more RAM?)” (
    As we will see, most of that is basically not true.

What is true is that the M5 Pro and the M5 Jr. were introduced in 1983, one year after the M5. They were sold only in Japan. The price of the M5 Pro was 39800 Yen, and the one of the M5 Jr. was 29800 Yen. At the same time, the price of the M5 was reduced in Japan to 49800 Yen.

The point which the above sources are missing is that the M5 Pro is not the extended version of the M5, but the cost-reduced version of the M5 with the same features in the same case (but a different color scheme). It is neither faster nor has it more RAM. Also no built-in power supply, but exactly the same external power supply as the M5.

The difference between the M5 Pro and the M5 is the PCB. The M5 Pro PCB (Revision M5C-1B) is smaller, and uses different RAM chips (HM6116P-4 instead of TMM2016). The RF box is not mounted on the PCB anymore, but resides in the case next to the PCB.

There is also a strange switch that can be altered between H and L. On the M5 Jr. this switch is called “CH”, so I assume you can switch the antenna channels here.

The feature-reduced version of the M5 (and M5 Pro) is the M5 Jr. The missing features seem to be

  • the printer port
  • the video port (RF is still available)
  • the audio port

Addditionally, the power supply finally is integrated into the case. The PCB again is different from the M5 Pro (Revision M2C-01A). The case is slightly changed and the joystick ports moved to the front (which makes so much sense for a games console). The price is 25% less than the M5 Pro.

Z80 CPU, Japanese home computer: is the M5 family MSX-compatible? Well, no. It is using the same graphics chip as MSX computers, and a similar (but not the same) audio chip. But M5s have not enough RAM to meet the MSX standard, and they do neither have the MSX BIOS nor the MSX Basic.

While researching the M5 family, I found that the M5 Pro and the M5 Jr. were also offered in Japan under a different brand, namely as two models (?? and 84S) of the “Sanno Primary Computer” family. There are also other computers sold under this brand, but as the cases look the same as in the Sord case, they are easy to recognise. The Japanese “Sanno Institute of Management” had as its mission to computerize the Japanese schools. This program was lead by the Sanno Institute of Business Administration.

There you have it. The M5 Pro and the M5 Jr. are Japanese-market-only cost-reduced version of the M5. They are quite rare.

Technical Data

Manufacturer: Sord
Model: M5 Pro
CPU: Z80A @ 3.58 Mhz
RAM: 4 kB + 16 kB Video RAM
ROM: 8 kB
Graphics: Up to 256 x 192 at 16 colors, 32 sprites
Audio: 3 channels with 8 octaves, 1 noise channel
Interfaces: Power, Tape, Parallel, 2 x Game Pads, Audio, Video, RF (NTSC), Cartridge
Dimensions: 262x185x35mm, 800 g.
Introduced in: 1983
Initial price: 39800 Yen


IBM ThinkPad 730T

January 24, 2021

As some of you know, I’m very much interested in Tablet computers of the 1990 that are able to run PenPoint, the Operating System the company GO developed for the first “real” pen computers.

The computer IBM send into the race for this first pen computer was a new product, a tablet computer they christened “ThinkPad”. This product did not take off and they re-used the name for the new line-up of notebook computers. In order to fit the old tablet computer into the new naming scheme, they re-christened the tablet the “ThinkPad 700T” (T is the “slate” tablet version in the ThinkPad line-up).

All ThinkPads, of course, are basically PCs, and can run (in this case also) Windows. Therefore, the tablet ThinkPads could still be sold even though PenPoint as an Operating System (although much better adapted to a computer operated by a pen) did vanish very fast from the market.

The successor of the 700T was the 710T, which was then suceeded by the 730T. The final iteration of the T-Models was the 730TE. All of these models (well, at least the 700T and the 730T) can run PenPoint. If you want to know the differences between the T-Model, here you are:

RAM4-8 MB4-12 MB4-8, max 20-24 MB4-8, max 20-24 MB
Display10″ STN VGA, 8 Gray scales9.5″ STN VGA, 16 Gray scales9.5″ STN VGA, 16 Gray scales9.5″ STN VGA, 16 Gray scales
Weight2.8 Kg2.49 Kg1.77 Kg (2 Batteries)1.77 Kg (2 Batteries)
ThinkPad Tablet Slates Data

The 730T that I bought at Ebay was very cheap, but also clearly broken (which I knew). Its display has a strange wobbly-wave-like surface and has underneath some broken areas. The case is covered in a white crystalline powder and the material is very brittle and sticky. Therefore a good candidate for opening the device and contribute some PCB photos. Here they are.

730T PCB, top
730T PCB, bottom

The internal RAM (8 MB in my case) comes as a “Panasonic Memory Card”, a daughtboard with a strange connector. The RAM can be expanded with special PCMCIA cards.


Technology Museums and Collectors: Question Time: An FAQ (German)

January 3, 2021

At the last VCFB 2020 I moderated an event on “Technology Museums and Collectors: Question Time“. The event was held in German because the event related to the situation in Germany (i.e. German museums and Collectors). The rest of this post is the German FAQ that resulted from that event.

Technikmuseen und Sammler: Eine Fragestunde: Die FAQ

Zusammengestellt von Fritz Hohl (

Es kommt die Zeit, da sich ein Techniksammler fragt, ob seine Sammlung nicht größeren Zwecken als nur der Befriedigung des eigenen Sammlertriebs dienen kann. Es gibt doch Museen, und ist deren Zweck nicht die Volksbildung? Man könnte die Sammlung doch einem Museum spenden, die wären bestimmt froh, zumindest die seltenen Stücke zu bekommen…

Im Rahmen des (virtuellen) Vintage Computing Festivals Berlin 2020 fand am 11.10.2020 ein Workshop mit dem Titel “Technikmuseen und Sammler: Eine Fragestunde” statt.

Ziel dieses Workshops war es herauszufinden, wie Technikmuseen arbeiten und was die Rahmenbedingungen für deren Arbeit sind, um es so Computersammlern zu ermöglichen abzuschätzen, wie Sie mit Technikmuseen interagieren können. Dies sollte durch Fragen an einige Kuratoren in Rahmen eines Workshops erreicht werden.

Aus diesem Workshop sollte dann die FAQ, die ihr gerade lest, erstellt werden, um die wichtigsten Fragen und Antworten zu dokumentieren, ohne daß einzelne Kuratoren auf einzelne Antworten festgenagelt werden können und so in Gefahr gewesen wären, unverbindlich zu antworten oder sich eine Antwort museumspolitisch absegnen zu lassen. Daher wurde die Veranstaltung auch nicht aufgezeichnet. Diese FAQ gibt daher ausschließlich die Meinung des Moderators wieder, die sich in einzelnen Fällen mit den Meinungen einzelner Workshopteilnehmer überschneiden kann, aber nicht muß.

Auf dem VCFB 2020 gab es darüber hinaus auch noch drei (aufgezeichnete) Vorträge von Museen, die
sich und ihre Konzepte und Prozesse vorgestellt haben, und die für die Leserin dieser FAQ von
besonderem Interesse sein könnten:

Wie sammeln wir als Museum Computer oder wie kommt ein Brotkasten ins Haus?
von Dr. Christian Berg, Heinz Nixdorf MuseumsForum

Computer sammeln im Museum: Die Informatiksammlung des Deutschen Technikmuseums
von Eva Kudrass, Deutsches Technikmuseum

Führung durch das Oldenburger Computer-Museum
von Thiemo Eddiks, Oldenburger Computer-Museum

Die folgenden Kuratoren haben am Workshop teilgenommen:

  • Dr. Carola Dahlke (Kuratorin für Informatik und Kryptologie, Deutsches Museum)
  • Thiemo Eddiks (1. Vorsitzender OCM e.V., Oldenburger Computer-Museum)
  • Eva Kudrass (Leiterin des Sammlungsbereichs Mathematik und Informatik, Deutsches Technikmuseum)
  • Dr. Jochen Viehoff (Geschäftsführer, Heinz Nixdorf Museumsforum)

Moderation: Dr. Fritz Hohl (Blog

Ein Ergebnis des Workshops war die Einsicht, daß die vier vertretenen Museen drei verschiedene
Typen von Museen repräsentieren.

Einrichtungen öffentlichen Rechts

Dazu gehören z.B. das Deutsche Museum und das Deutsche Technikmuseum Berlin.
Solche Institutionen können z.B. keine Objekte aus ihrer Sammlung verkaufen.


Dazu gehört das Heinz Nixdorf MuseumsForum. Alle Sammlungsobjekte gehören der GmbH, die damit natürlich auch frei entscheiden kann, was sie damit macht.

Museen in privater Trägerschaft

Dazu gehört das Oldenburger Computermuseum. Diese Museen haben keine einheitliche Trägerstruktur.
Beim Oldenburger Computermuseum z.B. sind alle Objekte jeweils Privateigentum einzelner Sammler, aber es gibt einen Verein, der das Museum betreibt. Deshalb können dort auch die einzelnen Sammler entscheiden, Stücke einzukaufen oder zu verkaufen.

Fragen und Antworten

Q: Was sind die Kriterien, die entscheiden, ob sich ein Museum für einen Computer interessiert?
A: Die privaten Museen entscheiden darüber individuell.
Die öffentlichen Museen haben u.a. folgende Kriterien:

  • brauche ich das Stück für die nächste Ausstellung?
  • tendenziell: je kleiner, desto lieber
  • passt das Stück in mein Sammlungskonzept?
  • funktioniert das Stück?
  • kommt es mit Software?
  • ist zu dem Stück auch eine Nutzungsgeschichte dokumentiert? Zunehmend sammeln Museen nicht mehr nur Objekte und stellen sie aus, sondern wollen anhand der Objekte ein Stück Sozialgeschichte vermitteln. Alles Material, das mit dem Objekt mitkommt und diese Geschichte erzählt (und vor allem, wenn diese Geschichte relevant ist), macht ein Objekt interessanter

Q: Woher bekommen Museen Stücke?
A: Dazu können wir uns ansehen, was eines der Museen über 2019 berichtet hat.
Es hat 150 Angebote erhalten, 139 Schenkungsangebote und 11 Kaufangebote. Von diesen hat es 6 Schenkungen angenommen und 2 Stücke gekauft. Von diesen Stücken hat es eines nach 2-3 Monaten in die Ausstellung geschafft (weil es eine ungewöhnliche historische Bedeutung hat).

Q: Wie hoch ist das typische Ankaufsbudget?
A: Das Budget ist für den Informatikbereich bei verschiedenen Museen unterschiedlich und liegt typischerweise zwischen 1000€ und 4000€/Jahr. Nein, nicht pro Stück, für alles zusammen.
Man sollte dabei die langfristigen Kosten für die Museen nicht vergessen, über den Daumen gepeilt sind diese 5 – 10 Mal so teuer wie der Kaufpreis des Objektes.

Q: Wieviel Stücke sind im Depot?
A: Die Museen haben typischerweise im Informatikbereich zwischen 4000 und 25000 Exponate, wobei ein Museum etwa 20% der Exponate im Ausstellungsbereich hat und 80% im Depot. Dieses Verhältnis ist bei verschiedenen Museen unterschiedlich.

Q: Wieviel Platz ist noch im Depot?
A: Bei allen Museen liegt der Füllstand in ihren Depots bei etwa 120%…

Q: Kann ich ein Museumsstück kaufen?
A: Von öffentlich-rechtlichen Museen auf keinen Fall. Bei anderen Museumsformen muß das nicht ausgeschlossen sein, ist es aber in der Praxis (zu deutsch: Nein).

Q: Kann ich ein Museumsstück tauschen?
A: Im Prinzip ist das möglich, beschränkt sich aber bei öffentlichen Museen auf andere Museen als Tauschpartner.

Q: Ich möchte meine Sammlung an ein Museum schenken, geht das?
A: Aus dem obigen geht bereits hervor, daß ein Museum typischerweise keinen Platz hat, und auch nicht mit der Bürde einer Mischung aus Schrott, Dubletten, und interessanten Geräten kämpfen will. Museen werden sehr gerne gefragt, ob sie sich für eine Schenkung interessieren, möchten sich aber die Geräte, die sie haben wollen, aussuchen. Die Einrichtungen öffentlichen Rechts sind zur Einhaltung ihrer Sammlungskonzepte angehalten und können daher nicht frei über eine Annahme einer größeren Sammlung entscheiden.

Q: Ich möchte, daß das Museum meine Sammlung als Sammlung ausstellt, geht das?
A: Nein. Vielleicht, wenn mit der Sammlung auch genug Geld mitkommt, die Sammlung zu lagern, aufzubereiten, zu inventarisieren, zu unterhalten und auszustellen…

Q: Wo kann ich mich darüber informieren, was ein Museum im Depot hat?
A: Zwei Museen nutzen Museum Digital ( um einige Stücke zu präsentieren, das sind aber eher der kleinere Teil. Intern benutzen zwei Museen die Software MuseumPlus, ein Museum eine selbst erstellte Datenbank. Diese internen Verzeichnisse sind nicht für die Öffentlichkeit bestimmt. Die Hürden, diese Daten der Öffentlichkeit zur Verfügung zu stellen sind rechtlicher Art (Rechte an Bildern) und Mangel an Humanressourcen, auch wenn die Museen das eigentlich gut finden würden.

Q: Kann ein Technikmuseum meinen Computer schätzen?
A: Nein. Ist weder deren Aufgabe noch deren Stärke.

Q: Was machen Museen mit den Stücken, die sie bekommen, zuerst?
A: Verschiedene Museen gehen hier verschieden vor. Die einen nehmen v.a. alle Batterien und Akkus heraus, die anderen geben sie direkt ins Depot, bei wieder anderen hängt das vom Alter und der Seltenheit des Stückes ab. Restaurierungsforschung ist in diesem Bereich ein aktives Forschungsgebiet.

Q: Helfen Euch Ehrenamtliche?
A: Den meisten Museen helfen Ehrenamtliche, auch wenn manchmal das Problem besteht, die richtigen zu finden bzw. solche, die gut als Gruppe harmonieren. Nur das HNF darf aufgrund ihrer Rechtsform keine Ehrenamtlichen einsetzen.

Thomson TO9+

December 27, 2020

I recently bought a Thomson TO9+ on ebay because I wanted to add another videotext model of a homecomputer family to my collection. It is a rare model, but of a (at the time) succesful manufacturer, so I thought there would be certainly enough information out there so I did not have to write a blog entry. Turned out that there is quite some information, but mainly in French, so maybe some more English details do not hurt. Here we go.

Nico201214, CC BY-SA 4.0, via Wikimedia Commons

Thomson was a French electronics manufacturer (freshly nationalised in 1982) that produced homecomputers from 1982 to 1989. Thomson had a TO (Tele Ordinateur) and a (more downmarket) MO line of computers, all based on the Motorola 6809 CPU (in fact, all of their models used a 6809 at 1 Mhz). Thomson was a very popular computer manufacturer in France (partly because most schools used their devices), but did not see a huge success in other countries (they also exported some models to Germany, Spain, and Switzerland). The most distinctive feature of Thomson computers was the light pen. It was delivered with each of their first models and available as an option for the later models.

In contrast to its predecessor, the TO9, the TO9+ had

  • Basic 512 as oposed to Basic 128
  • 512 kB RAM instead of 192 kB
  • a double sided floppy disk drive (640 kB) instead of a single sided one (320 kB)
  • an integrated modem
  • more programs delivered with it
  • the mouse port in the base, not the keyboard
  • two ports for mice or joysticks compared to a single mouse port

There was also an export version of the TO9+ that had a QWERTY keyboard, a serial port instead of the built-in model, and a PAL (antenna?) output instead of a SCART one.

I started this article by saying something about a videotext version of a previously introduced family of computer models. You see, in 1986 there was no widespread use of the Internet outside Universities and a few companies. At that time the nerd in the know would use mailboxes to connect to the world (the start of the web is still 7 years away, and the widespread use even longer). The only thing that was available for electronic communication on a more widespread national (not even international) level was videotext (or Minitel, or Peritel, or BTX as it was called in different countries). This system used a terminal at the users and a central server infrastructure that made everything work. The terminals were non-general-purpose computers of some complexity, to be connected to TVs. The terminal hardware required an officially authorized 1200/75 bps Modem and some graphics capabilities that were not easy to fulfill by 1983s home computers. Therefore, a few computer manufacturers (especially in France where Minitel, the French variant of videotext, was very popular) decided to bring out versions of existing computers that included a suited modem, fulfilled the graphics requirements, and that also had the videotext terminal software on board. For the Exelvision company, this were the Exeltel VS/VX models, for Oric this was the Telestrat, and for Thomson this was the TO9+.

The TO9+ was delivered with four programs on floppy disks:

  • Paragraphe (text processsing)
  • Fiches et dossiers (database)
  • Microsoft Multiplan (spreadsheet)
  • A communication program
    In contrast to the TO9+, the programs the TO9 was delivered with were contained in ROM. This was a problem as some of the programs on the TO9 had bugs and their bug fixes could not be integrated in the delivered machines easily. You can find a version of the programs the TO9+ was delivered with on the website “dcmoto” in the references.

The TO9+ was basically the top-of-the-line model of Thomson’s homecomputer lineup. However, due to the late introduction year (1986) and the high price (7500FF), this model was rarely sold. In that year you could already buy an Amstrad CPC 6128 for much less, and an Commodore Amiga or Atari ST (10000FF) for not so much more given that they had a performance that was much higher. After the TO9+ Thomson also introduced a PC compatible model and then ceased producing microcomputers in 1989.

TO9+ were always rare due to their price and their competition in 1986. Therefore, there are very hard to come by today.

Technical Data

Manufacturer: Thomson
Model: TO9+
CPU: Motorola 6809E @ 1 Mhz
RAM: 512 kB
ROM: 80 kB
FDD: 3.5″ disk-drive
Text: 40×24 / 80×24
Graphics: from 160×200 to 640×200
Colors: from 2 to 16 among 4096
Audio: 3 channels, 7 octaves
Basic: Microsoft Basic 1.0 and Basic 512
Interfaces: Light Pen, 2 * Joystick or Mouse, Keyboard, Centronics, FDD, SCART, Cartridge, Cassette, Audio, Bus slots (2), Telephone
Dimensions: 105 × 440 × 300 mm
Introduced in: 1986
Initial price: 7490 FF, about 1925 € in 2016


Epson EHT-10

October 26, 2020

Epson created the first “true laptop computer” with the HX-20. It was released in July 1982 and weighed 1.6 Kg. The successor to the HX-20 was in 1984 the 2.3 Kg PX-8 which was now capable to run CP/M due to its Z80-compatible CPU. The next model, the 1985 PX-4 combined features from the PX-8 and the HX-20, was also Z80-based and offered CP/M. I could not find the weight of the PX-4, but it was probably in the range of the HX-20.

The HX-20, the PX-8, and the PX-4 were all laptop computers, i.e. they required a desk or at least a lap to sit on so you can use it with your hands. But there are usage scenarios that require a more mobile device, i.e. one that you can hold in one hand while the other one uses the device. It is technically possible to use e.g. a HX-20 for this purpose, but it’s not comfortable at all.

So if you are a device manufacturer like Epson and want to serve the market that needs that higher mobility, what do you do? You design a version of the PX-4 that is lighter and that you can hold in one hand. Voila the Epson Handy Terminal (EHT)-10 family from 1986 onwards.


The (original?) model, the EHT-10 is a (from a today’s point of view) massive beige brick with an on/off switch at the top and an enormous 7-inch black-and-white display. It is mainly a touchscreen that you use with your finger, no pen required.

The basic usage scenario of the EHT-10s is mobile data entry. But you do not need to develop your application on the EHT-10, in fact, you can’t. You develop it instead on a desktop CP/M machine, and then simply transfer it to the EHT-10. To that end the EHT-10s are equipped with both CP/M 2.2 and the basic runtime environment that allows to run Epson Basic programs (e.g. coming from a PX-4). All you have to take into account are the different display sizes and input possibilities. This does not mean that you can get a CP/M shell on the EHT-10 or an editor to enter Basic programs; the EHT-10 is purely an execution device. You can transfer your programs to an EHT-10 either by serial connection, or by “IC Card”, or burn it on an EPROM and stick it into the conveniently located socket next to the main battery. So, you cannot program on the EHT-10, but you can connect the EHT-10 to your development computer by using a “Development Cartridge” for debugging purposes.

The main battery of the device is a proprietary 4.8V, 700 mAh NiCd module which gives the device a runtime of 8h. In case you have to change the battery, there is a secondary RAM backup battery (4.8V, 45 mAh). Using the stock power supply it takes 10h to load the main battery and a whopping 45h to load the secondary one it was completely empty.

On the sides of the case, at the bottom, there are two massive buttons to which you could strap a ribbon, so the device could go around your neck, thus freeing also the other hand if needed.


The other two models of the family are, first, the EHT-10/2b which looks like an oversized calculator with its 4-line display and its 34 keys (there is even a CALC key which puts the device in basic calculator mode). Apart from that, it’s innards are the same as the EHT-10’s.
The second model is the EHT-10/2 which is a EHT-10/2b without a backlight.

I received my two EHT-10/2bs (plus a printer) together with a simple 5.6V, 0.4A travel power adapter with a connector crudely welded to it. I have a 64 kB and a 128 kB RAM model. Using this power adapter I could never get the 128 kB model to run for more than a few seconds even connected to the power adapter, but the 64 kB model worked fine. And if you think about it, this makes complete sense. There was no main battery in any model (because they would be quite proprietary NiCd modules), but the backup cells were still in there. No, if you load the backup cells, the (battery-buffered) RAM immediately run on the cells, and even if they are full, the power needed by 128 kB is seemingly larger what the backup battery can deliver when switched on. The 64 kB model need less power and can run on my power adapter. The stock adapter had 6.0V anyway.

Epson produces many printers, and there is a clip-on dot-matrix printer model that fits the top of any EHT-10 device (it even uses a tiny ribbon cassette which you find even today on ebay).

There are almost no Internet sources on the EHT-10. The only one is listed below. It contains some photos (actually showing the very devices I ended up with), some (but unfortunately not all) manuals and the development software meant for CP/M or MSDOS desktops.

Epson sold these devices from 1986, but they were not the first company to target the ultra-mobile market. The first company probably was DVW (later on Husky Computers) with their Husky line of devices from 1981. The competition to the EHT-10 at the time was probably the 1984 Husk Hunter 2 which weighed 1.15 Kg, and had to be held in landscape mode, where as the EHT-10 was below 1 Kg, 50% smaller, and could be used hanging from the neck. The CPU and OS on both the EHT-10 and the Husky Hunter 2 was very similar.

Another competitor would have been the much lighter and cheaper Psion Organizer II from 1986, but it was much more proprietary in terms of CPU and OS, had much less RAM, and was much slower than the EHT-10.

Progress cannot be stopped and Epson later on gave up the EHT-10 family for the 1991 EHT-20, EHT-30, and EHT-40, which were PC- and DOS-based devices for the same usage scenario (all looking quite similar to the original EHT-10). The final model was the 1995 EHT-400c which was a small color-screen pen-based Pen Windows 3.1 tablet.

Epson EHT devices are probably quite scarce today because they were probably never distributed over normal computer stores (but to system integrators) and they were very pricey (which they could be in the beginning because there was not much competition). As a piece of industrial equipment, though, only a few people are interested in them.



  • CPU: Z80@3.68 MHz (CMOS)
  • RAM: 64-256 kB
  • ROM: 128 kB System ROM, up to 128 kB Application ROM
  • OS: CP/M 2.2
  • Batteries: main: backup: NiCd cells
  • Interfaces: RS232C, Barcode Scanner, IC cards
  • Dimensions: 21.3 x 9.3 x 3.8cm
  • Weight: 600g without main battery
  • Display: 12 x 14 characters (5 x 14 characters out of which can be used as a touch screen), 84*154 pixels


  • same data as the EHT-10/2b, but without the backlight


  • same data as above except the
  • Display: 20 x 4 characters, 120 x 32 pixels, with backlight
  • Keyboard: 34-key-calculator keyboard

Reference (yes, this time it’s only one)

Vintage Computing Festival Berlin 2020

October 8, 2020

In contrast to some other events, the VCFB 2020 will actually take place. This weekend (depending on when you read this), on October 10th and 11th, it will take place via a Wiki, BigBlueButton, and some streaming.

Find all important information on

Most exhibitions, presentations and workshops are in German, but there are also some English things:

I will also hold a presentation (on “Collecting Computers as an hobby: An Introduction“), but it will be given in German (as some information relates to the German situation).

Also, I will moderate an event on “Technology Museums and Collectors: Question Time“, but again, in German, because these are German museums.

Siemens Nixdorf PCD-3 Psl/20

October 8, 2020

Recently, on Ebay I discovered a variant of the NCR 3125 that I did not know: the Siemens Nixdorf PCD-3 Psl/20.

I did not buy it, but from the picture it seems quite clear that this is, in fact, a NCR 3125. Also, the name seems to hint to the 3125′ 80386SL CPU at 20 MHz…

VTech Logo Computers

August 5, 2020

I am always fascinated about computers with a programming language other than Basic in ROM. You might have heard of computers with Forth (e.g. the Jupiter Ace), maybe even APL. But do you know any computers with LOGO as their first language? No? Then you probably also do not know the company with the largest lineup of LOGO-computers. Any guesses? No, it’s VTECH!

You might pretend that you don’t know VTECH, but that would be very unlikely given that they are in business since the mid-70s and that their products are still sold in a big shop near you. VTECH is a Hongkong-based electronics company and my impression of them was always that they started selling computers in the 80s, and cleverly never changed their architecture afterwards, just their target market. However, that’s not really true.

VTECH (short for Video Technology) started their business in the mid-70s with a PONG console (what else?). They followed this up with LED-based games (looking like old calculator displays), then LCD-based handheld games. In 1982, they released their own games console, the CreatiVision. We might know VTECH for their 1980s line-up of home computers (and similar devices), the Laser family of computers (i.e. the Z80-based Laser 50, 100, 200, 210, 300, 310, 350, 500, and 700, and the 6502-based Laser 128, 2001, and 3000).

Next to their “serious” home computer line, VTECH also started in the 80s to build up a line-up of educational devices targeted at kids that soon imitated the looks of serious computers, either desktop models, or, later on, notebook models which makes one think of them as toy computers, especially when a tiny, black-and-white LCD display is mounted in a normal-size notebook lid, resulting in a huge bezel. Initially, these models were also based on Z80 CPUs.

Now, lately, I watched Nostalgia Nerd’s Youtube episode on VTECH (educational, toy) Laptops (, and I was very surprised to learn that there was a model from 1998 which even had the programming language LOGO built in.

This puzzled me because there is no other computer with a built-in Logo in ROM (as far as I know). Sure, there were quite some Logo modules and interpreters that could be added to all sorts of computers, but no manufacturer chose to provide this as the initial choice and in ROM.

So, I started to explore this road a little bit. What is the CPU Logo is interpreted on? How many models did VTECH produce with Logo? How good is the interpreter? There is not much information about these aspects on the Internet (probably you can find all of it in the references section). So, here is what I could find out.

All the models with Logo were a single generation of VTECH educational computers that were produced between about 1997 and 2001. This generation was probably all based on the same or at least a similar System-on-a-chip (SoC) architecture plus a RAM chip (the Black Magic CX had 128 kB of static RAM) that was completed by a conventional masked ROM chip that had up to 2 MB of ROM memory.

Unfortunately, we do not know the exact SoC model(s) that were used for sure, but the MAME code trying to emulate some of these computers use “CR16B” emulations. CR16B is a version of National Semiconductors 16bit “CompactRisc” architecture that can address (you guessed it) up to 2 MB of code/data. We don’t know for sure because, unfortunately, the SoC is bonded directly on the (very small) PCB, with a drop of epoxy on top of it, and no helpful labels on the PCB.

Main PCB of the Black Magic CX

However, the friendly decapping nerds from Team Europe decapped the SoC of a 6600 CX (see References) and produced a picture of the chip underneath the epoxy. It looks as if the die has a label that reads “NSC1028”. They also cite a press release from 1999 saying: “National Semiconductor designed the Geode NSC1028 processor specifically for VTech’s new email appliances. The system-on-a-chip integrates a powerful 16-bit RISC processor, keyboard and printer ports, LCD display controller and speech synthesis circuitry into a single piece of silicon. This custom integrated processor represents the first step in a partnership between VTech and National to bring attractively priced, easy-to-use information appliances to the consumer market.”

BTW, it seems to me that this line of Geode-branded SoCs has nothing to do with the x86-compatible line of Geode processors based on Cyrix technology that was sold later on to AMD.

The Logo is a nameless, quite basic version of the programming language. It is rudimentarily explained on 2.5 pages in the manual of the device, and consist of 25 drawing commands (turtle graphics), 15 mathematical functions, 9 “word and list” commands (don’t forget that Logo is a descendent of Lisp), 3 logical functions, 17 “other” commands, and 11 “flow control” commands, resulting in 80 commands overall.

If we compare this to e.g. to Commodore’s C64 Logo (by Terrapin), we find 37 drawing commands, 20 mathematical operations, 16 word and list commands, 7 flow control commands, and 66 other commands, 146 commands in total. The differences lie mainly in the larger range of devices that can be addressed on the C64.

Words and lists (in the Logo sense!) must not have more than 20 characters. Apart from that it is not known how much memory is available to the Logo interpreter, or whether there are other restrictions to the language. It seems to me that the interpreter is very, very slow, at least when graphics are involved.

The VTECH devices do not only offer the Logo interpreter (and editor mode), but also three groups of sample programs, ready to be edited if needed. When using the editor, Logo programs can be stored to either the internal (battery buffered) memory or a storage cartridge if you have one.

The different VTECH computer models had partially different displays, varying in size and resolution. The basic model (e.g. the 5005 X) had only a 5.4″ display with a resolution of 130 x 50 pixels (still giving you 4 or 5 lines of text). The deluxe Black Magic CX has a whopping 7.1″ with (about) 237 x 138 pixels. Unfortunately, because VTECH needed to appear modern, the usable area for Logo programs is much smaller as there is a window border around the area, and command icons on the right and the bottom. As a result, e.g. on the Black Magic CX, you can use maximally 202 x 86 pixels under Logo.

Apart from the English version, there was also a German version of Logo that is completely localized language-wise even down to the command names. So if you have e.g. the 5005 X model which features both English and German, you get also an English and a German Logo! Apart from German I did not find another language Logo was localized to (although I could check this only for the Genio 6000 model which has Spanish and English software. The Spanisch software offer also the English Logo.
For the later, deluxe model (the Black Magic CX) the Logo part of the manual was even extended heavily. Now, you are introduced through 10 pages into Logo (plus the extended explanation of the commands), quite a nice change.

Now to the question of which models of this generation do have Logo on board. This question is a little bit hard to answer as

  • there is no comprehensive, worldwide catalogue of VTECH devices
  • different language versions of basically the same machine have different names

So it’s up to lists of machines where the Logo feature we could ascertain. Here is my current list:

Power Zone 2000

Year: 1997
Format: Desktop with separate keyboard, see-through case
Display size: large, probably 18.1 cm = 7.1 inch, 237 x 138 pixels, with background light
Languages: English

PC Endeavour

Year: 1998
Format: Notebook
Display size: small, probably 5.4 inch, 130 x 50 pixels
Languages: English

Power Zone Edge

Year: 1998
Format: Desktop with separate keyboard, see-through case
Display size: large, probably 18.1 cm = 7.1 inch, 237 x 138 pixels, with background light
Languages: English

Power Zone Plus Notebook

Year: 2001
Format: Notebook
Display size: small, probably 5.4 inch, 130 x 50 pixels
Languages: English

Power Zone Plus Desktop

Year: 2001
Format: Desktop
Display size: small, probably 5.4 inch, 130 x 50 pixels
Languages: English

Genius 5005 X

Year: ???
Format: Notebook
Display size: 13.8 cm = 5.4 inch, 130 x 50 pixels
Languages: German & English

Genio 6000

Year: ???
Format: Notebook
Display size: 13.8 cm = 5.4 inch, 130 x 50 pixels
Languages: Spanish & English

Genius 6600 CX

Year: 1999
Format: Notebook
Display size: small, probably 5.4 inch, 130 x 50 pixels
Languages: German

Genius 8008 CX

Year: 2000
Format: Notebook
Display size: large, probably 18.1 cm = 7.1 inch, 237 x 138 pixels
Languages: German & English

Genius Tabletop Black Magic CX

Year: 2000
Format: Desktop with separate keyboard, see-through case
Display size: 18.1 cm = 7.1 inch, 237 x 138 pixels, with background light
Usable pixels under Logo: 202 * 86
Languages: German
Keyboard: wireless (infrared) keyboard with connector for the mouse
RAM: 128 kB Static RAM (GM76v8128cllfw70)

In conclusion, VTECH produced a number of models of educational computers offering a built-in Logo interpreter. Given the typical volumes of VTECH products, this makes them the largest (and only) manufacturer of Logo computers. If you want to own one yourself, get a model with the large screen.

Genius 9009 CXL

Year: 2000
Format: Notebook
Display size: large, probably 18.1 cm = 7.1 inch, 237 x 138 pixels
Languages: German & English


EO 440

June 22, 2020

From time to time I am baffled that I own a computer that I do not have a blog entry about. Either I had at the time of purchase too much going on and forgot or I felt at the time that there was already enough information available in the Internet. However, as I did quite some research on some adjacent areas (which I reported on in this blog), I feel I should do the honors for this model. Meet the EO 440, a pen-based tablet computer with an usual CPU.

Wbvanrij at English Wikipedia / Public domain

According to some sources, the 440’s (and its bigger brother, the 880’s) claim to fame is that PC Magazine called it in 2012 the the first true phablet. But that’s, of course, not the real story here. The point of the EO 440 is that it should have been the first pen-based tablet with a dedicated operating system. It should have been (but wasn’t) because it was conceived (and nearly built) by a start-up company that was one of the first that forsaw the potential of a computer that one uses like a block of paper (with a pen): the GO Corporation.

I could now paint you the picture of this company, but I already made a presentation on that in 2017 (English slides here, recorded German presentation here). The presentation largely follows the 1995 book of Jerry Kaplan (the founder of GO) called “Startup: A Silicon Valley Adventure”. It is a very entertaining book on the specific history of GO, and a good example of how startups work and what troubles they face.

GO incorporates in 1987, and subsequently develops a hardware prototype and an operating system to go with it. It uses an Intel 80286 processor. In January 1991 finally GO presents the Developer’s Release of their operating system called PenPoint. At that stage, PenPoint is already licensed to three other companies, namely IBM, GRiD, and NCR who want to use it on their own hardware developments. You may ask how to develop for PenPoint without GO hardware? Well, after all the prototype hardware is basically only a PC, and you can use several PCs models with specific graphic tablets to simulate the system.

In March 1991, Microsoft (that battled GO on every event stage since years) presents PenWindows, an add-on for Windows 3.1. This allows Windows to be used with a pen instead of a mouse and a keyboard, but (obviously) cannot change the structure of a Windows program in order to adequately support a pen. As a result, users have to e.g. hit UI elements with a pen that are far to small, and have to use the virtual keyboard too often. All Microsoft attempts that use a pen (including Windows CE) fail, and it is maybe this problematic experience that leads to a Microsoft that tries in 2012 to come up with a Windows version that is primarily meant for pen-based tablets although the majority of computers it runs on do not have a pen. This version, of course, is Windows 8.

In June 1991 NCR presents the first tablet that can run PenPoint, the NCR 3125 (proudly designed in Germany). It weighs 1.5 Kg and costs about $4800…

In April 1992 IBM presents the original ThinkPad computer which is a pen-based tablet (and weighs 2.8 Kg). It can run PenPoint. Tablets will not be a hit product for many years (spoiler alert :-), so IBM re-uses the “ThinkPad” trademark for its line of notebook computers (renaming the ThinkPad to ThinkPad 700T so it fits in the overall naming scheme). In case you ever wondered why a Notebook computer is called “pad” without resembling a pad or having a pen…

Apple starts selling the Newton in May 1992. It weighs only 400 grams and costs only $700. Although not sold in huge numbers, the Newton is probably the bestselling pen product of its time.

Where did all this leave the EO 440? And why is it called EO, not GO?

Well, in 1991 GO finds itself choked on the mobile PC market. Microsoft controls the PC operating system market and makes it impossible for GO to find manufacturers for components like BIOS or to sell their operating system to smaller PC manufacturers. The solution seems to be to change the CPU to a RISC model, thus not competing in the PC market. They have two choices: ARM or a chip from AT&T called the Hobbit. Apple just has decided not to use the Hobbit CPU and to switch to ARM for the Newton. When in doubt, GO (as maybe also other startup companies) always decides not for the objectively best option, but for the one they have to use as they are (again) short for money. AT&T, short of a customer for their Hobbit project, offers 10M$ in capital, so they go with the Hobbit (EO will be the only company to ever use the Hobbit and AT&T closes the Hobbit project down some months later).

As another consequence of the deal, GO has to cut out the hardware development division from the company and contribute it to another company AT&T wants to invest in. This new company is called EO (which means GO in Latin…). After that, GO is a pure Operating System company. GO finally releases version 1.0 of PenPoint in April 1992.

In November 1992 finally EO presents their first two models, the EO 440 and the EO 880, but sells them only from April 1993. The design has not the clear, time-less esthetics of the NCR 3125. It is designed by Frog design and has two ear-like protrusions on the top. These protrusions do not have a technical reason, the designers wanted to have them. It has a 7.5″ monochrome display and weighs 1 Kg. This is much handier than the 1.5 Kg of the NCR 3125 or the 2.8 Kg of the ThinkPad, but much heavier that the 400 grams of the Newton even if the Newton has a much smaller display of 5.2″ and can offer only roughly a quarter of the resolution of the EO 440.

The EO 440 sports a 20 Mhz Hobbit CPU and between 4 and 12 MB of RAM. PenPoint is provided on a 8 MB PCMCIA card. The computer offers serial, parallel, PS/2 keyboard, SCSI and VGA interfaces as well as a PCMCIA card slot. The 7.5″ monochrome display has a resolution of 480*640 pixels. Harddisks are optional. The EO 440 cost $2000 initially. There was also an optional mobile phone module which added a handset and an antenna, so you could use your device as some sort of smartphone… The batteries lasted abouth 3h.

The differences of the EO 880 to the 440 are a larger display, a 50% faster clock for the CPU and a much higher weight (and price).

Handwriting Recognition

The key of using a tablet and a pen in the same way as paper was considered to be handwriting recognition. This ability largely determined also the computational needs which exceeded what mobile computers until then had to provide. The handwriting recognition algorithm-wise seems not to have been a problem given enough computational power was provided.

This need was a problem for some 1993 pen tablets, namely the Amstrad PenPad which used a Z80 variant, the Z8S180 at 14.3 MHz and the Zoomer incarnations (e.g. the Tandy Z-PDA) which uses a NEC V20 at 10 MHz. This was the reason for the PC-based pen tablets to start at Intel 80386SL CPUs and for EO and Apple to look at RISC CPUs. For the Newton, every model used a faster ARM chip and early models were known for their sluggishness.

The need for a high computational power drove also the price and the battery requirements, which in turn increased the weight. Therefore, US Robotics’ Palm series of pen-based PDAs later on decided on another design alternative and did not attempt handwriting recognition. Instead, the user had to learn an easily recognizable alphabet (“Graffiti”), so the Palm could use a simple 68000-family CPU. This lead to a cheap, light-weight device that became very popular.

PenPoint as an Operating System

PenPoint supported the following features:

  • Priority-based, preemptive multitasking with processes and threads
  • Interprocesscommunication and semaphores
  • 32-bit flat memory model
  • Ability to run on RAM-only as well as disk-based computers
  • Support of DLLs
  • Heap memory allocation with transparent relocation and compaction (no fixed-length buffers)
  • Object-oriented message passing and subclass inheritance
  • Detachable networking and deferred data transfer
  • All hardware dependencies are isolated into a “machine interface layer” to facilitate porting to a wide variety of hardware and processor architectures
  • Kernel runs on both PC and pen-based machines

User-interface wise, PenPoint programs use mainly (paper) notebook metaphors. You could use tabs to go to a certain part of the notebook, you could have different notebools in a bookshelf, you had tables of contents and so on.

On a page you had the usual means of GUIs of the day: drop-down menus, buttons, scroll margins, the lot.

Also you had a number of commands you could execute with your pen on pages: the pen gestures. You could insert text, remove and edit text, call the options or selecting things.

BTW, PenPoint requires a portrait orientation of the display. Windows wants a landscape orientation. You can typically see for what operating system a computer model is meant when you look at the orientation of the manufacturers logo and the buttons 🙂

PenPoint-based computers are very rare today, the EO 440 is even rarer, and even more so the EO 880. Typically the NiCd batteries are long gone, and sometimes you do not even have a power supply. Some years I was lucky enough to find a EO 440 and last year I could purchase even a power supply for it!

Technical Data

EO 440EO 880
CPUHobbit @ 20 MHzHobbit @ 30 MHz
Display7.5″, 480 * 6409.4″ backlit
RAM4 – 12 MBsame
Portsserial, parallel, PCMCIA, PS/2 keyboard, SCSI, VGAsame
HDD (opt.)20 MB64 MB
Weight1 Kg1.8 Kg
Initial price$1999$2499


Gepard – Part 8: The 3rd life of the Gepard

May 23, 2020

Somewhat unexpectedly another person contacted me and told the story of the 3rd life of the Gepard. This person is Hans Carlos Hofmann. I already read his name before as it appears in copyright notices of some of the later versions of GDOS. As it turns out, he can shed some interesting light on the history of the Gepard after the phases I explained earlier. So, in the following, please find his information (translated from German by me). In the following, “I” means Hans Carlos Hofmann.

I received at that time the source code of the compiler from Mr. Müller as well as license to distribute it as a binary for computers of the Gepard architecture. The reason for that was that modifications of the compiler were needed in order to support MMUs (for the Motorola 68030) and FPUs (for the 68020 and 68030).

I, together with another student, then also developed GDOS further as I had a need for computational power. This other student was Harald Hellmann who developed the data processing for the measuring system for the ion drive at the University in Gießen.

I then used the finished system for my theses in Math and Physics so the system was also represented in the “Experimental Physics II” department (Ion drives were and are a topic in the Experimental Physics I department, translator’s note). At that time I validated a program written by Martin Berz, today a professor (at MSU, translator’s note) that calculated ion optics. The validation took place by comparing the results from his program with the ones from my independant implementation in Modula 2. Thanks to Modula, my implementation was more readable, but could not be run on a CRAY. I’m still a little bit proud in that the most errors could be found in his implementation.

The improved operating system that we called “OS/Science” (you will see in a moment why) received many, partially spectacular modules.

The first module was the interrupt handler. The original Gepards did not do interrupt handling, all the PCBs had was a simple jumper to order the CPU to get an auto vector. A program had to handle interrupts itself. If a program exited, e.g. due to an exception, an active interrupt jumped into nowhere, and you had to reboot the computer. All these problems were solved by my interrupt handler by dynamically creating machine code for the current situation. Using this handler, all the drivers were updated, one by one, so no polling was necessary anymore. This ended up that later applications could stand up to 3000 interrupts per second.

Exploiting this ability a “virtual processor” module (nowadays these would be called threads) was developed that ended up in a preemptive multitasking scheduler offering cooperative multi-user management. The latter features was added due to Modula-2 because else the compiler would have needed modification.

After the Gepard Computer company had ceased to exist, not only HS Computer built Gepard clones, but also the MediSyst company of Prof. Dr. Dimpfel (which existed until September 2005, translator’s note).

With my metrological applications I helped a lot of people to get their PhD, enabling quite spectacular presentations like these ones:

The technology of representing data by dynamically generated code was then used in other modules and applications. One of these applications was a Raytracing program from the begin of the 1990s. It computed an entire day for a single picture and heavily swapping data in and out using the MMU as there was 20 times more memory needed as existed physically. Here are some examples of the generated graphics:

Info Graphics
Visualisation of Atomic Force Microscopy

The “Gepards” were then built until the beginning of the 2000s. New cards were added, e.g. better graphic cards. One Atari (ST)-compatible graphics card could be used both for text and graphics, one that could switch between 1 byte color for every pixel and having 8 different, monochrome pixel layers, and one based on an Intel GDP chip that could execute graphics command in hardware. One big strength of the system was that, already in the 1990s, I could use up to four displays with realtime graphics.

Other things added were a SCSI subsystem for hard disks, tapes, floppy disk drives, optical drives, ZIP drives, CD and DVD drives, photo typesetters, a relational DB, a video subsystem, and a NFS V2 server.

Unfortunately, there was no new CPU/memory board among the new things. HS Computer did develop a Motorola 68040 prototype card, but the design turned out to be unusable due to problems that could not be solved in software. In a system like the Gepard where the bulk of the software is compiled by the onboard compiler, there is this chance to compensate for hardware bugs by centrally providing suitable code generation. The same problems occurred when a 68060 prototype was tried out. MediSyst wanted even to develop a 3 x 68030 + memory card but failed out of economic reasons.

The successor company of MediSyst, MEWICON CATEEM-Tec had the last generation of Gepard-like computers in production until early May of 2020(!). Due to the economic consequences of the Corona virus the now 75-year-old owner of MEWICON (and MediSyst), Prof. Dimpfel has now decided to close his company. Therefore, only a few weeks ago I had the honor to switch off the probably last of the Gepards in production – after over 30 years of Gepards still being used at the one or the other location.