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Tesla PMD 85 (PMD 85-3)

PMD 85 is a computer designed by Engineer's Roman Ki��e team. It was produced in Tesla Pie��any. Mainly used in schools in Slovakia, as teaching aid (Information Technology). Many interfaces of this computer shown it also good to teach Automation and to control industrial machines. In today's Czech Republic IT was taught mainly using IQ151 computers.
PMD 85 was continuation of PMD computer series: starting with PMD 81 (not much popular because of high price and lack of software), PMD 83 (not much popular because of poor performance, lack of software and keyboard made of telephone keys). This telephone keyboard survived to PMD 85-1 model. In 85-2 it was replaced by something a bit better (yet the keys are a bit small to type quickly from the first try).
PMD 85-2 had better keyboard and it could be left running for longer than first version (less heating components).
PMD 85-2A had 64K of RAM.
PMD 85-3 was another step forward - Mainly the same as 2A, but less overheating, it could run for hours. It had much better switching power supply with last-stage linear regulation. Engineers added more ROM making Monitor program better, yet incompatible (compatibility mode was included).
In Didaktik Skalica, Didaktik Alfa and Beta computers - clones of PMD, were produced.

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Manufacturer	Tesla
Origin	Czechoslovakia (Slovakia)
Year of unit	1988
Year of introduction	1985
End of production	1989
CPU	8080
Speed	2MHz
RAM	48K/64K
ROM	8K
Colors:	4
Sound:	Beeper
OS:	Monitor Basic Pascal
Display modes:	Text: 25x48 Graphics: 288x256
Media:	ROM cartridge External tape recorder	Power supply:
		Male 5-pin DIN at the computer. 1 - +5V DC 2.5A 2, 4 - GND 3 - +12V DC 1A 5 - -5V DC 0.4A P.S. The pinout etched on PSU case is pinout of INNER soldering fields (not the same in all models, some are different than these markings), NOT pinout of DIN plug.
I/O:	Serial Tape IO RF output Luminance video IMS-2 (IEE488 merely compatible) Two parallel ports System bus ROM expansion
Possible upgrades:	Not known
Software accessibility:	Possible (dedicated sites)

My unit was heavily used in some factory, where it was driving SUF16CNC numerically-controlled metal milling machine. It has markings from Tesla Kolin (Czech Republic), probably the machine was used there.
Photo on this page shows it as it came. It has been restored a bit: the huge crack near display connector has been chemically repaired. Unfortunately these stains above K-keys are unerasable.

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Contents:

Starting

Recording media

Joystick

Pinouts

Links

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Starting:

First thing: Reset is Shift+RST.

If no cartridge is in computer, it'll boot to Monitor. This program allows simple memory manipulation and IO.

Loading binary (not Basic, Pascal etc.) program from tape requires to switch to Monitor. To do it from BASIC, press Shift-RCL.
If required, PMD 85-2 mode may be switched in -3 version by typing:

JUMP FFF0

Now loading command should be used (instead of 00, use number shown by Emulator's Tape Manager, usually 00):

MGLD 00

After program loads, use JUMP to run program:

JUMP 1234

Where 1234 is program's loading address - every program has its own one. To determine it, try to load PTP in emulator and see "starting address" of file.

Loading from BASIC is simpler:

LOAD 0

Now play tape. It loads... Should display program's name.

RUN

Loading BASIC program from ROM cartridge:
If a BASIC program is placed in cartridge after BASIC iterpreter, you have to use Basic's ROM statement:

ROM 0

to run first program after BASIC.

 

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Recording media

You can play PTP tape images by sound card using PMD-85 emulator's tape manager - just click a speaker button.

Better way is to use PTP Manager - it can also read PTP from data played to sound card input.

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Installing joystick:

Schematic is copied from program accessible here:

You must connect this to GPIO connector, pins are designated on drawing. See pinouts for exact pin numbering. Remember about ground wire, pin 1 at the bottom of picture.
For KC507 you can use BC167, BC182 or BC237. For KA206 use normal 1N4148.

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Pinouts:

Let's begin with the simple things. Connectors in PMD are not labeled any way, so we need to explain what is where. We will start on the left side of the computer:

The male DIN connector is power supply connector. Small one is RF output for connecting TV, the last one, female DIN5, is video output.

Video connector:

1 - Composite sync 2 - GND 3 - Green/Luma 4 - Red 5 - Blue

I could not get RGB from it. The fastest way to get any picture is connecting grounds and pin 3 to composite input of the monitor.
 

Here's the rear connector:
 

Tape connector:

1 - input 2 - Ground 3 - Output 4 - n.c 5 - n.c

 

Serial connector (V.24):

1   - Data IN+ 2   - GND 3   - Data OUT+ 4   - Data IN- 5   - Data OUT-

 

 

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Links:

http://www.schotek.cz/pmd/ - Technical info, ROMs, simple emulator
http://pmd85.borik.net - The best emulator, games, ROMs, donwloads
https://github.com/jose1711/simpmd   - Emulator for Linux OS
http://pmd85.topindex.sk/ - PMD-85 emulation using Atmega processor.

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