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Zbrojovka Brno

Zbrojovka Brno (“Brno Armory”, the Brno arms factory) was a Czechoslovakian company whose diverse output included farm tractors and computer equipment. They are known for the Consul series of computers which used Hall effect keyboards. Many of the ICs for these keyboards were sourced from fellow Czechoslovakian manufacturer TESLA.

Keyboards

Examples

Known models include the following:

Model Hall ICs Encoder Reference
Consul 259.13 Unknown Dual TESLA MH1KK1 binary encoders plus Fujitsu MB7052 1 kB PROM eBay (ca. 1982)
Consul 262.3 MH3SS2 TESLA MH113 2-of-N encoder eBay (1987), eBay (1989)
Consul 262.12 MH3SS2 Intel D8748 µC Deskthority

Both 262 models use double-shot moulded keycaps, and the keycaps on those are distinctive, tall with a small step around the top. The Consul 262.12 example is of unclear date, the documentation is stamped “30 VIII. 1990” under “Datum vyskladnění” (“Date of removal from storage”) while the Intel 8748 (MCS-48 series) microcontroller is marked L4287050S, suggesting a manufacture date of 1984 (year 4 week 28).

Although the schematics indicate the use of “D”-type pulse sensors in various models, this has yet to be demonstrated in any discovered keyboard.

Schematics

The downloads page at consul.odkaznik.cz includes a number of keyboard schematic documents. An understanding of Czech is required to be able to make sense of the scanned material. Some keyboards have multiple variants and further investigation of the material is required to understand this; the table below simply reflects the details in the most basic form:

Consul model Hall ICs Encoder
259.11 MH1SS1 × 78 7400 Series TTL? with MH74S187 1024-bit mask ROM × 4
259.13 MH1SS1 + MH1SD1 MH1KK1 × 2 with MH74S187 1024-bit mask ROM × 6
262.3 MH3SS2 × 87 MH103 with MH74S571 512×4-bit PROM × 2, or MH113 (variant-specific)
262.4
262.5 MH3SD2 + MH3SS2 MH103 with MH74S571 512×4-bit PROM × 2, or MH113 (variant-specific)
2715 MH3SS2 MH1KK1 × 2

Models with MH1SD1 or MH3SD2 sensors are presumably N-key rollover on the same principle as Micro Switch’s implementation: each switch is only active for a brief moment, ensuring that it does not interfere with subsequent keystrokes no matter how long it is held.