Primo microcomputer family

Games

Computer management and BASIC programming training

Single people

Elementary and secondary schools

Information Technology History Exhibition

Structure

Central unit

Byte-organized machines: 8 bpB

• CPU: U880 microprocessor ( Zilog Z80 copy manufactured in the GDR), nominal clock speed: 2.5 MHz
  
• main store:
  • A, C and Pro:
    • 48 KB DRAM
    • 16 KB EPROM (four 4 KB cards)
  • B:
    • 16 KB DRAM
    • 16 KB EPROM (four 4 KB cards)
• calculator: ALU built into the microprocessor

Periphery

• backup:
  • tape recorder (BRG MK-27 or MK-29, with bandpass filter and amplifier matching)
  • B, C and Pro: FDU-1109 floppy disk, 5.25″, 35 tracks single-sided, capacity: 89600 bytes/disk or 80 files/disk (due to the address space of the disk catalog)

(For a detailed explanation of how to mount a floppy disk, see Primo Floppy Disk

• external devices:
  • keyboard:
    • A and C: touch (capacitive); (very cheap, rather unstable operation)
    • B and Pro: professional push-button
  • CRT display:
    • A and B: monochrome
    • C and Pro:: color expansion (32 colors from a 256-element palette)
  • B, C and Pro: Commodore IEC serial rail (can be connected to: serial joystick, barcode scanner, separate keyboard, Centronics printer driver, etc.)

Operation

Screen resolution:

• A and B: 16 rows, 42 chpl
• C:
  • text mode: 16 lines, 42 chpl
  • graphics mode: 256*192 pixels
• Pro:
  • text mode: 16 lines, 42 chpl
  • graphics mode: 256*256 pixels

Program set

• operating system: PRIMO BASIC System (burned into 16 KB EPROM)
  • The series is available on PBS 84.1
  • For series B PBS 84.2
  • For type C: PBS 84.2-C
  • CDOS disk system for Pro version
• compilers
  • for basic machine: BASIC (enhanced for color image processing in type C and Pro version)
  • For Pro version: (can be loaded from the storage)
    • assembler
    • Forth
    • Pascal

Historical curiosities

The original (working) name of the machine was Microter, a combination of the name of the manufacturing company and the word computer, and the fancy name of the power supply was Energoter. Later (before its release) these names were changed to Primo (= first ), or changed to PSU.

(The name Microter was printed on the box of the machine — probably due to an administrative error; the power supply is listed as Energoter on the warranty card.

The A series machines differed only in the color of the keyboard, and the C model differs from them only in that it was supplemented with a colored expansion card. Only ~ 10 copies of the AC model were made, and they were not commercially available. The description of the machines also includes a scathing opinion about the "touch" keyboard:

"I'm afraid we can't even talk about a keyboard, since there's no sign of a key on the machine, except perhaps for the RESET button. However, we can talk about a touchpad, a massage pad, and the nerve problems that can be caused by it. I'm afraid those who 'soon liked' this touchpad would quickly become familiar with bitter sugar, onion Napoli and perhaps poppy seed tripe as well."

Technical differences in Pro/Primo:

Although the color option panel is identical to the C model, in this case the color option pins were connected to the corresponding points on the motherboard, the Pro/Primo motherboard already had the appropriate ribbon cable connection location, and in addition, the motherboard, EPROM, case, keyboard, and power supply are completely different.

EPROMs were replaced with 24-pin EPROMs, which had a larger capacity and 28 pins, reducing their number from four to two. There were also some changes in their content: in addition to color management, new BASIC instructions supporting graphics were added.

The RAM slots are also different: in the A and B series, the fully equipped versions have 3×8, or 24, RAM slots, while the Pro/Primo motherboard only has space for 8 larger storage capacity slots.

There are also differences in other auxiliary circuits of the motherboard. The keyboard is actually a SZKI product, technically identical to the Uniboard professional keyboard manufactured there. What is interesting is that the pressing force of the keys was not provided by springs, but by magnets; and the buttons were not screen-printed, but were made by engraving. (The Uniboard keyboard was also used in the later SZKI professional computer family, the Proper 8 and Proper 16.) Due to the relatively high height of the keyboard, the original box had to be supplemented with a plastic heightening frame.

The power supply electronics are also different. The transformer has a higher power rating due to the additional panel's current draw and possible heating. The panel is also different, and a UA723 IC has been added.

“Although one of the goals of the School Computer Program competition was to support the Hungarian IT industry, and Pro/Primo won first place in the high school category and third place in the elementary school category, the absolute winner of the competition was the Commodore 16 computer family, which was sold at a reasonable price… Thus, Primo did not become a Hungarian ZX Spectrum” ( The Past of the Future, page 166.)

Despite this, his memory still lives on in 2020!

Resources

General Overview: Primo

More about the A and B series: Primo A and Primo B

Detailed description: The Primo

A thorough and professional analysis of the machine's properties: The Primo "people's computer" Mikrokomputer Magazin, 1984/6, 28.-29.

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