R12 computer

They were not applied.

There were no

Neither version has survived.

Structure

Central unit

SZKI:

Word-organized machine: 18 bpW (16 data bits, 1 parity bit, 1 write-protect bit)

• controller: (SSI and MSI encapsulated) circuits built from TTL elements; clock frequency: ~3 MHz
  • 2*2 KB (bipolar ROM) microprogram memory; cycle time: ~300 ns
  • 32 interrupt levels
  • Minibus rail system
  • control panel
• main memory: 1-4 pcs 8 KW ferrite ring RAM (2*8 KB modules), cycle time: 800 ns
• calculator: fixed and floating point arithmetic
• channel: IBM-compatible multiplex channel; microprogrammed control of external units, via their own interface card

VT:

Word-organized machine: 16 bpW

• All components are identical to the R10 machine, there is no separately evaluable data

Periphery

• backups
  • SZKI:
    • DISZKMOM fixed head hard drive (Sagem license), 300 KB
    • up to 4 EC 5052 (Bulgarian) hard drives
      • 7.25 MB removable disk packs
  • VT:
    • FEX3 fixed hard disk (Sagem), 800 KB, access time: 10 ms
    • floppy disk
    • magnetic tape unit
• external devices:
  • operator desk (VT340 monitor + console typewriter)
  • console matrix printer (LX 120)
  • punched tape reader (MOM)
  • punch tape punch (MOM)
  • punch card reader (VIDEOTON)
  • line printer (VIDEOTON)

Operation

Screen resolution: 16 lines, 80 chpl

SZKI:

77 microprogrammed instructions; basic mathematical operations hard-wired in hardware

Fixed-point operation speeds:

• addition/subtraction: 2.3 μs
• multiplication: 8.1 μs
• division: 9.1 μs

VT:

The R12's central processing unit was identical to the R10: its control system was instruction-level compatible with the Mitra 15, its instruction set contained 86 microprogrammed instructions, and both the microprograms and execution times were identical; but the main memory was also identical.

It was actually a "large" R10 configuration oriented towards data processing: its peripherals – instead of process control devices – included numerous external devices supporting data processing (magnetic tape units, magnetic disks, line printers, punched card readers, punched tape devices, etc.).

Program set

• operating system: rewritten IBM DOS
• compilers:
  • SZKI
    •  assembler
    • editor (Linkage Editor)
  • VT: na

Historical curiosities

It was a unique event not only in our country, but also in the CEEC, that one country produced two different versions of one model.

When the development of the R10 was entrusted to VIDEOTON by a central decision, SZKI immediately began developing the R12; the machine was later successfully approved.

During this time, VT switched to the development and serial production of the R11, and then successfully marketed the machines in the CMEA countries. It started with the R12 with some delay, and did not even submit this product for approval. Based on the available data, it seems more likely that the R12 designation was only a commercial and marketing code, and in fact designated a higher-speed and expanded set of external tools, more suitable for data processing purposes, the R10.

It should be noted that, due to the exemption granted in international treaties, neither the architecture of R0, R11, nor R12 was IBM-compatible, but the multiplex channel was, so any external device could be used with the machines for which the appropriate hardware interface and driver had been developed.

For example, the interface unit developed at SZKI for the EC5052 removable disks, in addition to writing the same cylinder and track as IBM, also handled the same file formats, meaning that information written on a large ESR or even an IBM machine could be written to and read back.

Resources

SZKI: József Csendes and Endre Nagy (oral communication)

VT:

• Zoltán Béla Ujvári (oral communication)
• The History of Videoton 1938-1990 (VIDEOTON Holding, 2012, ISBN 978-963-085110-7)