Archive for January, 2024

Sony PTC-500,-550,-300,-310 Family of Early PDAs

January 28, 2024

In the late 80s, early 90s, mobile computing still meant traditional text-and-keyboard devices although the computers used for that purpose were already quite small. You could get portable versions of WIMP desktop computers (e.g. the Macintosh Portable), but these computers required you to sit down in order to use them.

Mobile devices for casual use while standing required new paradigms like the pen-based computers from 1991 onwards (yes, there was the 1989 GRiDPad 1900, but this was a too rare model and the Operating System was basically an unaltered MS-DOS).

One of the difficulties of pen-based computers was that you really need some sort of handwriting recognition in order to exploit the full potential of such an approach. The problem is that you need a lot of compute power to do that, more than what was available for a small computer at that time that can be hold in one hand if you wanted to have a battery life of more than two or three hours. This problem would haunt almost the entire first generation of devices that wanted to do so until mobile CPUs become more powerful (or until Palm came up with its “Graffiti” input method which simplifies the problem from recognizing any handwriting to recognizing exactly one handwriting that the user had to learn).

This problem of entering text into a mobile computer is much worse if your language is not alphabet-based, but consists of several thousand symbols like Chinese or Japanese. For these languages, in the early 80s even displaying all characters was not trivial, not to speak of designing a keyboard that allows one to efficiently enter the needed symbols. For these languages the use of a pen or brush is not only convenient, but a necessity.

And so, finally, we are in the time, use case domain, and country where Sony saw a need for a pen-based PDA (Personal Digital Assistant) in Japan in 1990 (a PDA is an electronic appliance that aims to be a digital multi-tool for all your Calendar, Address Book, and Notebook needs, and that ideally, can be synced with your desktop computer). And that’s exactly what Sony designed: it’s family of “PTC” PDAs, which came out only in Japan (PTC means PalmTop Computer and you find Sony’s “PalmTop” logo all over these products).

Sony PTC-500

The first model was the PTC-500 released in 1990 for 198000 Yen (or about 3200$ in 2023). It was quite large (205x45x158mm closed) and heavy (1.3 Kg), but had a pen and could recognise more than 3500 Japanese and Western characters. The (electrostatical) pen still needed a cable to the computer, and you could not simply write anywhere on the display (although you could scribble everywhere), but had to fill pre-defined boxes with a single character at a time. In order to achieve this technical marvel (and it was a marvel at the time), Sony had to use the latest in algorithmic wizardry: Fuzzy Logic!

Fuzzy Logic expands the classical 2-value Boolean Logic (knowing only TRUE and FALSE) to a number interval between 0 and 1, with the ends encoding classical logic, but also being able to represent a logical level of e.g. 0.5. Fuzzy Logic values are able to represent vagueness and imprecise information. Applied to the problem of recognizing symbols I guess this allows for some level of tolerance when entering these symbols compared to the expected standard pattern of this symbol.

The PTC-500 was clearly targeted towards business people as depicted by the ads for that device.

It did not only look (when closed) like a black calendar, it also offered the applications that would be needed by traveling business men, e.g. the management of contact information. Showing a vaguely handset-like indentation on the upper half of the case tells you where to put the handset of your (fixed line) telephone because it can (touch-tone) dial a number from the contact list (as an accessory you could even get one of these external acoustic couplers which used a microphone and a small loudspeaker to receive and send data over a telephone line having a handset strapped on the top). Business-like was also the price of the PTC-500 (remember, the equivalent of $3200 nowadays). It had a large 512×342 backlit, monochrome LCD display with a diagonal of xx inch. Apart from a 2 MB ROM it also featured 320 KB of RAM.

The software of the PTC-500 falls into 3 main categories: Planning, Directory, and Idea Filing.

For planning, users can define “actions” that have a time period associated to them. These actions can be managed as To-Do lists or as appointments in a calendar.

The directory allowed to store contacts with many possible data fields like birthdays, address, phone numbers, etc. Different views on this data allowed to e.g. have a phone directory or a list of customers in a certain area.

The “idea filing” tool is a cross between a note taking and a presentation tool. It allows you to note down ideas and informations on cards and to categorize them, and also to create presentations that can be shown to customers.

A calendar, a world clock, FAX software and a tool to exchange files completes the software.

Data Modules

It was not easy to exchange data with a PTC PDA. There is no wireless (or wired) network that it can connect to and the device does not have a standardized card slot as the PCMCIA standard was only published in 1990. There is the proprietary extension interface, but if offers only a 2″ floppy diskdrive and an acoustic coupler as (optional) communication equipment. Therefore, all PTCs have an integrated (proprietary) solid state memory card slot for battery-buffered SRAM cards. The available sizes are 64 KB (PTM-064) and 256 kB, but I never saw the latter. Funnily, there was one other Sony device that could use these memory cards and that is the (Japanese) Video Titler XV-J777. This machine had a PTM-064 card included and (being basically an MSX2 machine) is interesting in itself (but this is a story for another day).

Other Models

The PTC-500 was replaced in 1991 by the PTC-550.

PTC-550

Instead of the (mainly useless) opens-like-a-book form factor of the 500, the 550 was a classical slate wrapped in a plastic cover. Therefore, it was a lot smaller when being used and about the same size when stowed away. The 550 weighs a little bit less and also costs a little bit less (30kYen less)

Also in 1991, a low-end model completed the line-up.

PTC-300

The PTC-300 halved the weight and almost divided the prize by 3. For that money, you got half the resolution, and a resistive instead of a capacitative pen (at least it did not need a cable anymore). You lose the extension interface, but gain an infrared communication port that lets you talk to other PTC-300s). One reason for the weight loss is that the device now uses a smaller, less widespread battery (which also can be replaced by 2 AA batteries in a holder). The PTC-300 has a lid on the side which contains also the pen when not used.

Finally, in 1992, the last model of the line is the PTC-310.

PTC-310

This is simply a PTC-300 without the lid but enclosed in a leather-like binder for a more upmarket look.

One problem of the PTCs is the usage of the early soft paint that many mobile products featured at the time. The problem with this generation of paint is that is turns into a sticky gooey mess after some time that costs one quite an effort to touch if not treated. The seller of my device has treated this problem, but even so e.g. the pen of my PTC-300 does not really want to leave its notch in the lid.

Sony PTC PDAs are, in my opinion, very cool, early devices, but you cannot develop your own software for it (I think). Being borderline appliances, not computers, and having being sold only in Japan (having a Japanese-only user interface and documentation), there are probably not many collectors attracted to these devices. The PTCs are quite rare even in Japan with the PTC-310 maybe being the rarest.

Sony did not produce further PTC models, but from 1994 re-entered the PDA market with their (2 model) line-up of Magic Cap devices, the PIC-1000 and PIC-2000.

PIC-1000

Especially the PTC-550 speaks design-wise a very similar language to the PIC-1000 from 3 years later. Also the PICs use a Sony videocamera battery, they also have a resistive pen (like the PTC-300s), it is a landscape format device, and a display with about the same resolution. The differences are that the PICs only weigh half so much, are much more graphically oriented, and are meant more for communication, also integrating a modem.

Regarding PDAs, finally Sony also produced their own versions of Palm-powered PDAs from 2000 to 2005 called the CLIÉ devices.

Technical Data

Model: PTC-500
CPU: Motorola 68HC000@8MHz
RAM: 320 KB
ROM: 2 MB
Mass memory: 320 KB battery-buffered RAM
Display: 512 x 342, backlit
Pen technology: capacitative with cable
Batteries: NP-55 (NiMH), about 6h runtime
Interfaces: power, 2-inch memory card adapter, proprietary 28-pin extension interface
Size: 205 x 45 x 158 mm closed, x 298mm opened
Weight: 1.3 Kg
Initial Price: 198 kYen
Introduced in: 1990

Model: PTC-550
CPU: Motorola 68HC000@8MHz
RAM: 320 KB
ROM: 2 MB
Mass memory: 256 KB battery-buffered RAM
Display: 512 x 342, backlit
Pen technology: capacitative with cable
Batteries: NP-55 (NiMH), NP-77H also possible
Interfaces: power, 2-inch memory card adapter, proprietary 28-pin extension interface, proprietary 26-pin interface
Size: 215 x 25.5 x 190 mm
Weight: 970 g
Initial Price: 168 kYen
Introduced in: 1991

Model: PTC-300
CPU: Motorola 68HC000@8MHz
RAM: 288 MB (battery-buffered)
ROM: 2.5 MB
Display: 320 x 256, backlit
Pen technology: resistive
Batteries: Sony BP-2PT (also BP-2EX and BP-2X might be usable), but there is also a holder for 2 AA batteries included
Interfaces: power, 2-inch memory card adapter, infrared
Size: 210 x 105 x 20 mm
Weight: 435 g
Initial Price: 65 kYen
Introduced in: 1991

Model: PTC-310
CPU: Motorola 68HC000@8MHz
RAM: 288 MB (battery-buffered)
ROM: 2.5 MB
Display: 320 x 256, backlit
Pen technology: resistive
Batteries: Sony BP-2PT (also BP-2EX and BP-2X might be usable)
Interfaces: power, 2-inch memory card adapter, infrared
Size: 210 x 105 x 20 mm
Weight: 360 g without / 560 g with cover
Initial Price: 68 kYen
Introduced in: 1992

References

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Small update on the tv-computersystem 6800

January 10, 2024

I recently brought the tv-computersystem to a vintage computer meeting in Stuttgart, Germany (click here if you are interested) and learned a little bit more about this machine.

The computer works when switched on (after around 48 years…) without even having to replace capacitors. We could not find the channel on a TV that gave us a stable or even unstable picture (although one could see that there was something out there somewhere).

So, a participant (thank you so much, Joachim Oswald!) proposed to try to convert the signal that goes into the tv modulator into a composite monitor signal and started on this endeavour right away (my electronics “knowledge” is so limited that I cannot only sit next to a hardware wizard and bring coffee if requested). It turns out there is already such a signal available on the PCBs! All you have to do is to

  • connect the (inner) pin of the cinch plug to Ground
  • connect the (outer) ring of the cinch plug to the “MO” pad on the power-supply-and-modulator PCB (the brown PCB)
  • Voila! Instant composite signal of a very good quality.
My computer connected to an 80s Philips Green Monitor
Here you can see the very good picture quality a little bit better

We experienced that the light pen did not work in the beginning, but increasing the intensity on the display did the trick (we used a green display where the bright parts might not be that bright as on a TV). Remember that the light pen will only work on a CRT display.

And now, for the first time, I could see a working tv-computersystem! I entered the first example program from the manual (adding two numbers) and it worked once I entered all needed values and selected “run”. The system is quite easy and smooth to use. The light pen works even a few millimeters above the CRT surface, and you can glide it easily from cell to cell. Together with the command to fill an entire memory page with the same value (that’s the first command on the top), entering values is quite fast (especially as you can enter hex digits), I imagine much faster than using switches and lamps.

I was now also able to (roughly) weigh the computer. It comes at about 3.5 kg in total.
weight

The last open question is about the clock speed the system uses. A M6800 of that era in a standard configuration would run at 1 Mhz, but I cannot confirm this yet. There is one quartz oscillator with 27 Mhz on a PCB (which seems to be a common sight at that time, especially for a device connected to a TV), but this cannot be simply divided down to 1 MHz by powers of 2, so this still is some sort of a mystery. There are circuit diagrams out there, I just did not have seen it yet. In the end, it does not matter that much on a device intended for teaching you how to program.

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Franz Morat KG tv-computersystem 6800

January 3, 2024

Recently, there was a computer on ebay.de which I never heard about before which turned out to be the quirkiest, most interesting and innovative model I learned about in a long time. No one else bid on it, so I got it for a low price. It is now the oldest computer I own. Meet the 1976 “tv-computersystem 6800” of the Franz Morat KG.


No, this is neither a power supply nor measurement equipment although the very generic steel case (in a fitting 1970s orange) and the very clean front plate (one on/off switch and a thing on a cable is all you get) certainly look like that type of devic

It is made by a small German company called Franz Morat KG from the High Black Forest muncipality of Eisenbach with about 2000 inhabitants. The company specializes in mechanics, custom drives, and plastic products. The muncipality and the entire region is well-known for their watch industry (think cuckoo clock if you are into stereotypes). So, in about 1975 someone from this industrious company decides that this is the right time for a computer product.

At that time, computers were a very uncommon sight in Germany. Big companies might have some very expensive, very big computers to do all this data processing witchcraft, but home computers will not really arrive in Germany until 1978 (with the Commodore PET 2001). Engineers can amuse themselves already with computer kits, but they require at least soldering abilities. The standard interface for a small computer these days is a long row of switches and lights that show the content of a single memory unit in binary. When you want to have a bit flipped, you literally flip the corresponding switch.

But, being the crafty German engineer that you are, you decide to make a very simple, relatively cheap computer that you can produce easily in-house and that people will buy because they want to learn to program computers. Keyboards are quite expensive and cannot be produced in-house. So, what about a purely electronic input device, let’s say a light pen? What, you don’t know what a light pen is? Meet the first broadly used direct input device for “graphical” user interfaces. It consists simply of a photo diode mounted on the tip of a pen connected to the computer. When the diode sees a light it means that the electrode beam of your CRT just passed underneath the position of your pen on the screen and showed a white pixel. The computer is very aware of this position because it controls this beam in order to produce a picture on the screen. Light pens are used since the 1950s and were common on the graphics terminals of the 1960s. Using a light pen also means using a CRT display. Hmm, that’s a cost issue. Computer monitors are very expensive (at that time). Well, there is one CRT display already 93% of all households in Germany own in 1975: a TV. So, lets produce an antenna signal for a TV to display.

Now, using a TV to show the output of a computer in 1975 or 1976 is a big innovation. From 1977 onwards, most home computers use a TV in order to save cost. But in 1976, only games consoles connect to TVs and until November 1976 when the Fairchild Channel F hits the (US) market, game consoles do not even have microprocessors. I’m sure there is a computer model out there that connected to a TV out-of-the-box before the tv-computersystem, but I could not find it. So, I claim that this model is the first and wait for the angry comments to prove me wrong 🙂

The resulting computer therefore has only 3 leads: One light pen, one power cable, one TV antenna cable, all permanently connected to the computer so you cannot lose them. Inside the box, the architecture is quite simple: you have a microprocessor, some small RAM (1kB), a 0.5 kB ROM (the initial brochure notes it down as the OG Intel 1702, the first available EPROM), a simple power supply, and a lot of discrete logic. Everything is housed on 5 PCBs, 4 of them connected at the edges with what would be nowadays would be edge connectors and ribbon cables (or maybe a backplane), but what is actually a long line of single wires connecting each PCB in a bus manner.


The PCBs slot in slits of simple pieces of plastic on the bottom and on the top: voilà the finished computer, at least the basic version. The basic version would have cost you 1294 DM, roughly a 1/10 of the price of the (then new) VW Golf GTI. If you spent 650 DM more, you could buy the luxury “C” version of the tv-computersystem that gave you a cassette interface and and external 37-pin bus interface.

To set this price in relation: in the same issue of a German electronics magazine that announces the tv-computer another article describes the private build of another 6800-based computer with a TV interface with less than 1kB of RAM but a keyboard imported from the US for a component cost total of 2000 DM.

Let’s talk a little bit about the logical architecture of this computer. What might astonish you (it certainly did astonish me) is that the basic model does not have any ROM whatsoever. None. Ok, you might say, where is the firmware? Is it a “clean computer” like some Sharp models that even has to load the firmware from a cassette? The answer is no: there is no firmware (at least in the basic model). All basic functionality of the computer is done in hardware. The user interface? Done in hardware. The light pen management? Done in hardware (actually there is an article in a German electronic magazine aptly named “Elektronik” from September 1975 that describes this latter circuit and it is probably written by the man who designed at least the circuit for the tv-computersystem). The microprocessor is not so much an enabler in this computer, it is the “system-under-test”, or, more correctly, it is, together with the RAM, the model of a computer system the device exposes so the user can learns its ways. From this point of view, the choice of the concrete CPU model is not really important, and now it does not surprise us that the manufacturer intended to offer different CPUs for it.

Now you might say, but, wait, I just saw you talking about a 0.5 kB ROM, what is all this no-firmware nonsense? Ah, you see, this ROM exclusively contains the library for using the cassette interface in the extended “C” model. And it is only available as a library. When you want to store to or read from a cassette tape, you need to write a small program calling the corresponding library subroutine and start it.

Ok, enough about the architecture. Let’s talk about the user interface (and remember, we are still talking about hardware). Here it is:


That’s all you get. The UI (basically a classical monitor) allows you to see the content of the RAM and to control the CPU, all of which happens by using the light pen. On the left side on the majority of the screen you can see 32 bytes of memory either as hexadecimal numbers or as bits. Each of these values has to fit into a 16×16 grid of cells. Each cell has a dot at the top left corner which is the target for the light pen if this cell is to be selected by the user. Next to the dot is the space for a single character, e.g. an hex digit. The rest of the controls can be seen on the right: a column with the 16 hex digits (each one in the same cell structure as in the values table) and a second column with the controls, also in cell structure. The controls column allows to scroll the values table through the memory, to set the value of one of the values table to a certain value, to fire an interrupt, to start, stop, and continue the execution of a program, and to single-step through a program.

Let me iterate once again that all the things that you see are generated by circuits without the help of the microprocessor. There is no bitmapped graphics and no text memory. When the content of a RAM page changes and if this page is the one you have selected for display, you will see this update very quickly.

Because the UI is hard-wired, you can also not change it. There is no command to display something on the screen. When your program wants to output something, you change the value in a memory cell and hope that the user is currently watching this page (or, less sensationally formulated, for any program you tell the user on which page he/she can see the results. This is done e.g. for the example programs in the [Book].

So, does this mean that a program cannot output anything graphical? Well, you can, in a way. Remember that I told you that the UI can display values either as hex digits or in binary (and that I, sneakily, showed you only a picture of the hex mode)? Here is a picture of the binary mode:

Binary Ui (Ignore the box on the bottom right corner)

As you can see, now the thing with the 16×16 value matrix makes sense. In hex mode, you need only four cells per value (because a 16-bit value can be expressed as four hex digits), but in binary, you need 16, and the entire cell space is displayed either black (being a 0) or white (being 1). You could argue that this is some sort of bitmap graphics with the sensational resolution of 16×16 pixels and two colors and that you have even 32 user-selectable pages of these graphics (and that you have a text mode with the small restriction that is can only show 10 digits and 6 (big caps) characters in a 4×16 grid. But it would be a bitmap and text mode where the output memory is also the code memory, and it is a bitmap where the user can also change the bitmap interactively. In every case, in my opinion, it is ingenious and certainly saves a lot of components that do not need to be designed for the computer and not being paid for by the buyer.

Because of all of that, programming on the tv-computer is rather bleak. Of course, there is no higher programming language, not even a symbolic assembler. You have to convert your assembler program (e.g. by using the provided paper programming forms) into numbers yourself which you then put into the memory using the UI. When you were ready, you select “run” on the screen and hope for the best. One advantage of the used Motorola 6800 processor is that it dumps its registers into memory after each interrupt, so in single-step mode, you can directly see the results of your assembler commands. The other aspect of being bleak is that you really get a deep insight into the 6800 machine code, that the computer is (very relatively) cheap, and that more comfort at that time comes with a hefty price tag, and many computer users are still accustomed to using computers with switches and lights. The Altair 8800 computer was released only a year prior and so was Microsoft Basic.

The tv-computersystem came with a German 250-page manual ([Book]) that describes usage of the computer and 6800 machine code in detail and contains many example programs. BTW, I scanned a copy:

tvc-bookDownload

Models

It is difficult to really tell what models really exist. The brochure talks about 6800-, 8080-, and SC/MP-based versions, but I never saw anything else than the 6800-based one. The brochure talks about two models, the “G” one (G = Grundausführung = basic model) and the “C” one. The “C” one contains a DIN (audio) cassette interface and an external, 37-pin extension bus whereas the “G” version does not have these luxuries. The pricelist also refers to 8080 “G” and “C” versions (having the same price as their 6800 counterparts). In reality, I saw two versions. My version is an orange, steel case “C” version with a single (power) switch on the front. The homecomputermuseum.de model has a nice wood case, and an additional switch at the front (marked “RAM”) and seems to be a “G” version where the PCBs on the inside are fixed by a single screw, which does not exist in my model.

Source: Boris Jakubaschk, Link: https://www.homecomputermuseum.de/sammlung/detailansicht/comp/Computer/show/tv-computersystem-6800/

I believe the tv-computersystem was sold really only in Germany, but in the references you can find an one-page ad for it in the UK-based magazine Electronics Today from 1977 from a company called Rotex which might have been located in the Netherlands.

ICs inside my tv-computersystem

The CPU is of course an original gold-capped Motorola M6800. The RAM consists of 8 2102-1PC 1 KB x 1 bit chips of different manufacturers. There is one MMI 6341-1 PROM (512 bytes) in a socket next to another, empty socket. There are 2 MMI 6331-1J chips which seems to be NiCR PROMs with the gigantic capacity of 32 x 8 bit each, so 64 bytes in total. The rest seems to be discrete ICs. No other Motorola 68xx family chips can be found. The 64 bytes of PROM solve a problem I was wondering about for some time. If your base, “G”, model has no ROM how do you produce the hex digits on the screen? The digits are in a 5×5 pixel matrix and you need 16 of these digits. This means you need to represent at least 25 * 16 bits or 50 bytes. This fits very well into a 64 bytes space…

From a collectors point of view, this computer, in my opinion, is a dream. It is an early, quirky computer with innovative, unusual features that is very, very rare, even in Germany. It is a self-contained unit where every significant cable is fixed to the unit and cannot get lost. It can be connected to a TV. It is virtually unknown in Germany, let alone any other country. It has extensive documentation (even if it is completely in German). As it is so unknown, the prices are (currently) quite low.

Technical Data

Manufacturer: Franz Morat KG
Model: tv-computersystem 6800
CPU: Motorola 6800@maybe 1MHz
RAM: 1 KB
ROM: 64 bytes + 0.5 KB (“C” model only)
Resolution: 16 x 16
Colors: monochrome
Interfaces: power cable, tv antenna cable, lightpen cable, 37-pin extension bus, cassette interface (DIN 5 pin)
Size: 255mm x 115 mm x 190mm
Weight: ~3.5 Kg
Initial Price: 1295 DM (“G”) or 1954 DM (“C”)
Introduced in: 1976
Produced devices: 2000 (estimated)

References:

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