This text is a 1:1 copy from

https://git.sr.ht/~adlpr/bk0010-01-programming/tree/main/item/bk0010-01-programming.md

To be sure to have it in the future, I keep it locally. All credits go to original authors of this document and its parts.

Electronika BK-0010-01 Programming Reference

Overview and basic operation

The Электроника БК-0010-01 / Electronika BK-0010-01 (hereafter “BK”) is a Soviet microcomputer intended for home and school use. It was manufactured from 1984 to c. 1993.

A BK enthusiast is known as a BeKashnik (БэКашник). 😎

Internals

BK hardware follows the Q-Bus scheme; all devices (CPU, memory, and I/O) are connected to a common bus through which control signals and data are transmitted.

• CPU: К1801ВМ1; 16-bit architecture, binary-compatible with the PDP/LSI-11 instruction set (1 , 2), plus extended instructions XOR and SOB (no MUL, DIV, ASH). 3 MHz clock, with e.g. register transfer operations requiring a minimum of 12 cycles, so a few hundred k op/s.

• RAM: 32 KiB = 16 x КР565РУ6.

  • 0.5K reserved for system variables and stack

  • 15.5K free for programming; can be increased to 27.5K (“режим расширенной памяти (РП)”/“expanded-memory mode”), overwriting first 12K of graphics framebuffer RAM

  • 16K (4K in expanded-memory mode) hardware-scrollable framebuffer; two graphics modes:

    • 256x256, 32 chr/line, 2-bit color (red, green, blue, black)

    • 512x256, 64 chr/line, 1-bit color (white/black)

• ROM: 32 KiB = 4 x КР1801РЕ2.

  • The first 8K contains MONITOR (МОНИТОР), the BK’s OS. It includes the keyboard driver, screen driver, tape recorder driver, and an 8x10 font.

  • In the 0010-01 model, the other three ICs contain a Vilnius BASIC 1986.07.24 interpreter.

  • With the MSTD cartridge connected, the upper part of the address space is remapped to that of the original model BK-0010: a FOCAL interpreter and a diagnostic test suite (and 8K of empty space where you could maybe connect another IC??).

For a very long time it was believed that BK-0010, unlike most home microcomputers, had no Western counterpart or prototype. Lately I’ve learned that BK-0010 looks very much like a trimmed Terak 8510/a. I am adapting my BK-0010/11 emulator to emulate Terak as well, using whatever documentation is available on BitSavers.

Keyboard

Function key descriptions, left to right, top to bottom:

Display

Display output consists of 25 lines of 8x10px characters, the first and topmost being a “service line” with information about current keyboard and screen operating modes.

There are two display modes, toggled by [АР2]+[;]:

• 32 characters per line: 256x256 2-bit color (black, red, green, blue);

• 64 characters per line: 512x256 1-bit color (black and white)

Graphics drawing (ГРАФ) mode

The key combination [АР2]+[⇩]+[5] toggles between text entry and direct graphics-drawing mode. On entering graphics mode, ГРАФ (for “графика”) will display on the service line, and the cursor will change to crosshairs, which can be moved pixel-by-pixel with the arrow keys.

Entering a decimal number followed by an arrow key will move the cursor that many pixels; e.g., [1][0][0][⭢] will move 100px to the right. Any non-digit entered will cancel this process.

To begin drawing, press [АР2]+[⇩]+[5]. ЗАП (“запись”) will display on the service line. Any pixel the cursor touches will be changed to the current color.

To erase previously drawn pixels to the background color, toggle [АР2]+[⇩] +[7] for СТИР (“стирание”) mode. Any pixel the cursor touches will be erased.

Edit Lock (БЛР) mode

The [БЛОК РЕД] key activates edit-lock mode (БЛР on the service line). Keys and input combinations that control editing will instead be inputted as visible textual characters, presumably facilitating the preparation of data sequences for programming, I guess.

Ports

Facing back of unit, from left to right:

Common expansions

• блок МСТД (Мониторная Система Тестовой Диагностики, Monitor System Test Diagnostics / MSTD cartridge): contains ROM for original model BK-0010 (FOCAL interpreter and test suite/debugger)

• блок нагрузок ( load [?] cartridge): tests operability of the parallel port, used in conjunction with the MSTD cart

• блок КНГМД ( KNGMD [?] cartridge): connect to 5.25" floppy drive

• блок КМ ( KM [?] cartridge): connect a printer and mouse. e.g. УВК-01 Марсианка , Электроника МС-6312

• блок Менестрель ( Minstrel cartridge): sound card with 2 channels, 9-10? octave range, effects: legato, vibrato, glissando, smooth tempo change

MSTD test suite and debugger

@@@@@@@@@@ note: I don’t have the MSTD cart so I can’t test any of this

The test system on the MSTD card includes a set of tests to check the health of the BK, and a remote debugger that allows you to view and modify memory contents directly.

To work with the test system, connect the MSTD cartridge and use the P T command to switch from FOCAL to the test system.

The test system command prompt is indicated by the + sign.

Digits 1 to 5 are the commands to run tests of: RAM and ROM, keyboard performance (designed for the earlier model BK-0010 keyboard), the parallel port, the character generator/image quality (?), and tape recorder operation.

To exit the test system to FOCAL, press К.

To switch to the console debugger, enter Cyrillic input mode (РУС key) and type ТС.

The debugger command prompt is indicated by the ¤ symbol. The debugger allows you to view and modify the contents of memory, as well as perform a number of operations with memory ranges. Key concepts are the current address (А) and * array length* (Д), together specifying a consecutive block of memory [А, А+Д).

All addresses and values should be specified in octal.

Memory map

By convention with this architecture, memory addresses are written in ** octal** (&xxxxxx).

System variables (&000000–&000777)

Interrupt vectors

Note that despite the existence of a clock register, there is no clock interrupt.

System variables

User RAM (&001000–&037777 or &067777)

Free for programming, but note that BASIC system variables are in &002000 –&003777 and should be free if you wish to utilize any of the BASIC arithmetic subroutines (see below section).

@@@@@@@@ TODO: move instructions on how to set expanded-memory mode here

Screen RAM (&040000 or &070000–&077777)

&040000 : topmost, “service” line

one line = 64 (&100) B, one character line = 640 (&1200) B

…

System ROM

MONITOR (&100000–&117777)

Power-on initialization is handled by the BK’s OS, MONITOR (МОНИТОР). This consists of setting the stack pointer, interrupt vectors, and other system variables, after which the screen is cleared and control passes to address &120000 . For the model BK-0010-01, this is the built-in BASIC interpreter, or FOCAL on the MSTD cart.

You can switch back to MONITOR command mode (from BASIC: MO), typically necessary for working with binary executables. Like BASIC commands, MONITOR commands may be used in full or abbreviated.

BASIC (&120000–&177577)

The built-in interpreter is Vilnius BASIC 1986.07.24. Not gonna detail it all here, pretty typical implementation, though as Wikipedia notes:

The dialect was very close to MSX BASIC. The major differences were the lack of the PLAY, SOUND, VPOKE and PUT SPRITE operators, the inability to open several files at the same time, and the inability to use more than one operator on one line.

Note that the string postfix is ¤.

Valid commands include: MO(NIT), RUN, CONT, CS(AVE), CLOAD, BS(AVE) , BL(OAD), LIST, ., DEL(ETE), NEW, REN(UM), CLE(AR), AU(TO) , CLS, COL(OR), PS(ET), LIN(E), CI(RCLE), PA(INT), DR(AW), FRE , LET, PRI(NT)/? (+ TAB, AT), IN(PUT), FO(R)/NEX(T), REM , DA(TA), REA(D), RES(TORE), DI(M), IF/TH(EN)/EL(SE), STEP , ST(OP), AND, OR, GOTO, GOS(UB), RET(URN), ON/GOTO, KE(Y) , SQR, SIN, COS, TAN, ATN, EXP, LOG, ABS, INT, FIX, SGN , RND, BIN¤, OCT¤, HEX¤, CHR¤, ASC, LEN, STRING¤, INKEY¤ , STR¤, VAL, MID¤, PO(KE), PEEK, OU(T), INP, BE(EP)…

Arithmetic subroutine addresses

All BASIC arithmetic function subroutines expect FP11 double-precision (64-bit) floating point inputs:

• b65 (1): sign

• b56-64 (8): exponent

• b0-54 (55): fraction

Calling these from outside BASIC requires a structure to be assembled in RAM consisting of 6 or 8 consecutive pointers:

1. For each operand (1-2 depending on the function):

   1. #&156170 (subroutine to push the value at the following address on the stack)

   2. Operand address

2. Desired function address (from below table)

3. #&156334 (subroutine to pop 4 words and store to the following address), unless the desired function is 16-bit int conversion (at &166760), in which case #&156350 (same but for one word)

4. Output address

5. Return address (probably the address immediately following your JMP)

Load a pointer to the start of this structure into R4, then execute JMP @(R4)+.

Steps 3-4 could be skipped if you’re fine with popping the values yourself, I guess.

Also note that the BASIC system variable area (&002000–&003777) should be free.

Registers

&177660 — Keyboard Status

Bit 0-5: unused.

Bit 6: (R/W) Keyboard interrupt: 0 = enabled; 1 = disabled

Bit 7: (Read-only) Set (1) when a new code is entered into the Keyboard Data register; cleared (0) on reading Keyboard Data register. If keyboard interrupt enabled (0), the keyboard interrupt is triggered.

Bit 8-15: unused.

&177662 — Keyboard Data

Bit 0-6: (Read-only) Encodes the last key pressed. No new codes are written until the previous code is read.

Bit 7-15: unused.

&177664 — Display Offset

Bit 0-7: (R/W) Initial value == &330. Changing this value by 1 corresponds to a 1-px vertical shift of the display output (positive = upward); i.e. in the screen RAM by 64 (&100) B.

Bit 8: unused.

Bit 9: (R/W) 0 = enable expanded-memory mode; 1 = disable.

Bit 10-15: unused.

&177706 — Timer Period

…

10 POKE &O177706,&O77777   'set period
20 POKE &O177712,&O160     'start timer
30 ? AT(0,0)PEEK(&O177710)
40 GOTO 30

&177710 — Timer

…

&177712 — Timer Control

…

&177714 — Parallel Port

• A1: output signal “RESET” – for the initial installation of an external device with the RESET command; the load capacity of the output is limited - the signal comes directly from the “INIT” output of the processor

• B1: input signal “IRQ2” – interrupt request signal from an external device; interrupt vector is located at address &000100

• A11, B11, A18, B18, A19, B19: ground

• A8, B8, A9, B9: +5V; in order to avoid overloading the BK power supply, it is not recommended to power devices from these contacts.

• Inputs: 2.4V~5.25V = 0; 0V~0.5 V = 1

&177716 — System External Device Management

Bit 0-3: (Read-only) processor operating modes (??)

Bit 4: (R/W) Read/write to/from the line (?? ИРПС?)

Bit 5: (R/W) Read/write data to/from tape recorder, or send ready signal to the line (?? ИРПС?)

Bit 6: (R/W) Read: 0 if at least one key is pressed, 1 “if all keys are pressed” (??). Write: transfer data to tape recorder / generate a (1-bit) audio signal (same line)

Bit 7: (R/W) Read: ready signal from the line. Write: drive tape recorder (0 = start, 1 = stop).

Bit 8-15: (Read-only) Program counter start address on boot; default is &100000 (i.e. bottom of ROM)

&177776 ???? — Processor Status (PSW)

…

Emulator traps (system subroutines)

EMT 34 display status word

EMT 40 serial transmission baud rate

Character map

Seems to be mostly an extension of KOI-8, ****with many ( afaict) system-specific control characters.

Control characters are written with their corresponding key or key combination in brackets; see above “Keyboard” section for descriptions of their respective functions.

Note that #&030 is backspace and #&010 is arrow left, strangely.

#&040 to #&176 : see ASCII/KOI-8, though with #&044 == ¤.

#&240 to #&277: Graphical characters; may be entered with [АР2] + the key in parentheses (i.e. corresponding to the code + #%40). The order of these make more sense in the context of the keyboard layout: box-drawing chars on the top 2 rows and “←→↑↓♠♣♦♥π” on the bottom.

#&300 to #&377: Cyrillic, see KOI8-R (i.e. with #&377 == Ъ).

References

• Программирование на БК-0010-01

• http://bukosek.si/hardware/collection/elektronika-bk-0010-01/bk-0010-01-manual.pdf

• BK-0010 Nostalgia Page

• Бытовой компьютер БК-0010-01. Дубль два

• Руководство пользователя. Эмулятор БК 0010(01) и БК 0011(М) для Windows XP / 7 / 8 / 10. Версия 3.10.