TEC FP-1500-25 serial printer

The Tokyo Electric Corp. FP-1500-25 is a daisywheel printer that was available from 1980 (possibly earlier) as a peripheral to the 8-bit micros of the time and it predates the original IBM PC by at least a year. It was sold under the Exidy brand (as shown on the title image) as a companion to the Sorcerer computer in the WPS 80/2 package as a DP-6120, and it might have been OEMed by other vendors as well.

TEC FP-1500-25 restored, shown with the tractor for fanfold paper

Unfortunately, almost nothing about this particular printer is available on the Internet, and the manual disappeared long ago. It seems to be based on a Diablo mechanism, as it uses Diablo-style typewheels and ribbons. Diablo, who pioneered daisy wheel technology and later were bought by Xerox, appear to have been a kind of standard back in the day for these kinds of printers.

Serial Printer with a parallel Centronics port…

Interestingly, even though the badge identifies it as a “serial printer” it connects via a standard parallel centronics cable. Therefore, the “serial” designation might mean that it renders text in a serial, character-by-character fashion as opposed to chain printers that formed a whole line of text at once and thus were much speedier. In fact, the -25 part of the model designation points to a 25 characters per second printing speed.

As such it seems that the TEC FP-1500-25 implements at least a part of the Diablo printer protocol, it will work with the D630 printer driver of MS Word under MS DOS as well as with the Text-Only printer driver under Windows 98.

As the seller, Klaus, told me, the printer had been in storage for about 20 years after being decommissioned. So, it had gathered quite a bit of dust and some mild corrosion.

It had been used in his own business to print invoices for IT consultancy and mainframe software development services. It was hooked up to a Northstar Horizon computer via a proprietry, 15-pin D-Sub parallel connector by means of a self-made cable.

Restoration

The restoration mainly involved cleaning and lubing and replacing a dead mains switch which made fizzing noises when connected to power. Apparently some corrosion had been going on in there, fortunately I had a similar switch from a japanese made device at hand which worked perfectly as a replacement.

Mains switch replacement, some corrosion on the casing

For properly servicing this device, it has to come apart, so I disssembled it up to a point where the case, electronics and the printing mechansim separated. It is quite service friendly – just disconnect the paper out and front panel connectors, unscrew the four feet and the mechanism lifts out. That way, cleaning up the hardened grease and re-lubing was much easier.

The printer is built in a pretty modular way, with the mechanism and the electronics backplane forming one component into which the individual logic parts plug, similar to ISA cards. It was probably possible to order other variants of the printer, for instance, with different interfaces.

Printer logic board: low voltage part of the PSU, CPU (i8085), motor driver board, IO logic board)

Aside from that, the machine is built like a tank. Even the case is cast aluminium, and only a few parts are made of plastic; everything else is metal.

8085 CPU Board and ROMs. Note the transparent tape on the EPROM UV Windows.

Testing

After re-assembly, it was testing time. Applying power didn’t release any magic smoke so we were good to go ahead. A bit of guesswork lead to finding how to initiate the self-test printing routine – it is holding down the page advance button (middle) while turning on the power.

The printer will start hammering away the selection of characters on the printing wheel, do a line feed and start over. That confirmed that both electronics and the mechanism were in working order.

I then replaced the printing ribbon with a new one from ebay – Diablo HYtype – and tested a little bit more with a computer connected. Its funny to see Windows 98 on the tiny Toshiba Libretto drive the more than 40 years old dinosaur just perfectly.

What is ESC 3 for?

The Diablo manual reveals a couple of tricks those old daisywheel printers had up their sleeve. One of those is “graphics mode” which is initiated by sending ESC 3 to the printer and terminated by sending ESC 4.

The effect of ESC 3 is to scale horizontal – carriage – and vertical – paper – movement such that one increment is no longer a character or a line but a fraction thereof which coincides with the size of the dot (.) on the typewheel.

Graphics printing on a text-only printer.

Printing graphics this way is crazy loud and takes forever but technically works. This obviously totally impractical to print full page images but for small logos or the like this might have been useful.

Below is a Processing script to convert an image file into the format this printer understands. Since the control codes are from the Diablo manual, it should work with other, Diablo compatible printers as well.

/* Simple conversion of an image file to 
 * Diablo graphics code.
 *
 * Image will be loaded from file, converted to
 * black & white based on the given threshold,
 * scaled down and then converted to ascii text
 * for output on a Diablo compatible daisywheel 
 * printer.
 */
char ESC=0x1B;
char LF =0x0A;
char BS =0x08;

String GFXON = ESC + "3" + LF;
String GFXOFF= ESC + "4";

int width=100;
int height = width;

size(400,400);

PImage img;
img = loadImage("/Users/timo/Desktop/TVC/logo_color.png");
img.filter(THRESHOLD, 0.4);
img.resize(width,height);
image(img, 0, 0);


PrintWriter file = createWriter("/Users/timo/Desktop/data.txt"); 

int dimension = width * height;
img.loadPixels();
file.print(GFXON);
for (int i = 0; i < dimension; i++) {
  color c = img.pixels[i];
  if (brightness(c)>127) {
    print(" ");
    file.print(" "); 
  }
  else {
    print(".");
    file.print(".");
  }
  if (i % width == 0) {
    print("\n");
    file.print(LF);
    for(int b=0;b<width;b++) {
      file.print(BS);
    }
  }
}
file.print(GFXOFF);

file.flush();
file.close();

TEC FP 1500-25 Technical Details

	TEC / TECToshiba FP-1500-25 aka Exidy DP-6120
Manufacturer	Tokyo Electric Corporation (now Toshiba)
Printer Type	Serial impact daisywheel printer
Interface	Parallel centronics
Protocol	TTY, possibly Diablo ESC sequences
Graphics	None, text only
Printing speed	25 CPS
Paper handling	Single sheet or endless fanfold
CPU	8085 (higher integrated 8080 variant)
Manufactured	<= 1980, this unit 1981(as per PCB labeling)
Price	USD $2,195 in May 1980 (as per Exidy price list) USD $8,413 inflation adjusted (as per April 2024)