Imported from GitHub: skiselev/radio-86rk · commit c5e9cb7 · license GPL-3.0

Description

Re-make of the Soviet Ham Radio computer published in Radio Magazine in 1986

README

Radio 86RK

Re-make of the Soviet Ham Radio computer published in Radio Magazine in 1986

Hardware Documentation

Table of Content

• Introduction
• Specifications
• Project Notes
• Hardware Documentation
  • Schematic and PCB Layout
  • Connectors
  • Bill of Materials
  • Memory Map
• Firmware Documentation
  • Monitor
• Release Notes
  • Changes
  • Known Issues

Introduction

This project is a remake of Radio-86RK - a soviet ham radio computer. The original design was published in Radio Magazine, an amateur radio and DIY electronics oriented publication, starting from April 1986. Hence the "Radio" and "86" in the name ("RK" stands for ham radio computer).

The goal of the original design was to create a computer that can be built relatively easily and cheaply using commonly available components. Therefore it included several short-cuts. For example it didn't use 8228 bus controller. Instead, it uses /WR and DBIN CPU signals instead to distinguish between write and read CPU cycles. Since the system doesn't decode I/O control signals, all the I/O devices are memory mapped. Another optimization is the use of DMA controller for both supplying the data to the CRT controller and for refreshing DRAMs. The system didn't support interrupts. The sound was implemented using INTE output of the CPU. The software would use EI/DI instructions to generate sound. There are no graphics capabilities. The font size was limited to 128 characters (8275 CRT controller limitation), and given that it had to support both Latin and Cyrillic ABCs, it only had capital letters for both ABCs. The CRT controller shares 16 MHz clock oscillator with the CPU (not uncommon in other home computers at that time period).

Despite the limitations, the design was fairly successful, many people have built this computer, and there are some that still building one, this project included. In addtion, several factories manufactured computers based on (but not always compatible with) this design - e.g. Mikrosha, Apogee BK-01, and a few more.

Specifications of the Original Design

• KR580VM80A (Intel 8080) CPU @ 1.78 MHz (16 MHz divided by 9)
• 16 KiB to 32 KiB DRAM, 2 KiB ROM (monitor software)
• KR580VG75 (Intel 8275) CRT controller which works together with KR580VT57 (Intel 8257) DMA controller. 1 KiB ROM is used for font
• Two KR580VV55A (Intel 8255A) PPIs. One is used for keyboard and cassette I/O, another one for the extension port
• Normally the computer consisted of 2 or 3 PCBs - the mainboard, the keyboard, and the keypad.

Modifications to the Original Design

• 16 DRAM ICs replaced with a single 32 KiB SRAM IC
• Font ROM size increased to 2 KiB, so that it fits an alternative font. CRT controller GPA0 attribute is used to switch between fonts.
• Reverse video attribute implemented in CRT controller
• Added 8251 USART and 8253 timer. The timer is used for dividing the clock for USART and for sound generation.
• Single board design, including an integrated mechanical keyboard
• The work is largely based on Radio-86RК-SRAM project created by Alexey Khudyakov (alexcp).

Specifications

• Processor: Intel 8080A / КР580ВМ80А CPU running at 1.78 MHz
• Memory:
  • RAM: 32 KiB SRAM
  • ROM: 2 KiB UV EPROM with system monitor software
• Video: Intel 8275 / КР580ВГ75 CRT Controller
  • Alphanumeric display
  • 2 KiB UV EPROM with font
  • Composite video output (50 Hz)
• Audio:
  • Intel 8253 / КР580ВИ53 (single channel)
  • CPU INTE output
• Parallel Interface:
  • Intel 8255А / КР580ВВ55А PPI
  • 26-pin expansion header
• Serial Interface:
  • Intel 8251А / КР580ВВ51А USART
  • DE-9 connector
• Built-in 67-keys keyboard
• Cassette recorder interface

Project Notes

Check Project Notes for the information about building this project

Hardware Documentation

Documentation for the Previous Versions

• Version 1.3
• Version 1.2
• Version 1.1

Schematic and PCB Layout

• Schematic - Version 1.4
• PCB Layout - Version 1.4

Connectors

J1 - Composite Video

Pin	Description
Tip (the inner contact)	Output: Composite Video
Ring / Sleeve	Power: GND

J2 - Power (5V)

Connect regulated +5V power supply to this connector.

Note: The 8080A CPU, clock generator, and serial port transmitters and receivers use +12V/-5V/-12V voltages. An on-board DC-DC converter (U26) is used to obtain these voltages. Instead of using the DC-DC converter it is possible to provide these voltages directly to the system using J3 connector.

Pin	Description
Tip (the inner contact)	Power: 5V (positive terminal)
Barrel / Sleeve	Power: GND (negative terminal)

J3 - Power (5V, 12V, -12V)

Connect regulated 5V/12V/-12V power supply to this connector.

Pin	Description
1, 2, 3	Power: GND
4, 5, 6	Power: 5V
7	Power: 12V
8	Power: -12V

J4 - Cassette Connector

Pin	Description
1, 2, 3, 8	Power: GND
4	Output: Sound output to cassette recorder (line level)
5	Input: Sound input from cassette recorder (line level)
6, 7	Not connected

J5 - Serial Port Connector

Pin	Description
1	Not connected: DCD
2	Input: RX
3	Output: TX
4	Output: DTR
5	Power: GND
6	Input: DSR
7	Output: RTS
8	Input: CTS
9	Not connected: RI

J6 - Parallel Port Connector

Pin	Description	Pin	Description
1	Output: PC0	2	Input: PA0
3	Output: PC1	4	Input: PA1
5	Output: PC2	6	Input: PA2
7	Output: PC3	8	Input: PA3
9	Output: PC4	10	Input: PA4
11	Output: PC5	12	Input: PA5
13	Output: PC6	14	Input: PA6
15	Output: PC7	16	Input: PA7
17	Output: PB7	18	Output: PB0
19	Output: PB6	20	Output: PB1
21	Output: PB5	22	Output: PB2
23	Output: PB4	24	Output: PB3
25	Power: +5V	26	Power: GND

Bill of Materials

• Radio-86RK project on Mouser.com - View and order all components except of the PCB, and most Intel 8xxx ICs.

• Unicorn Electronics is a good source for Intel 8xxx or compatible ICs, 7400-series TTL ICs, and 74LS00-series TTL-LS ICs

Component type	Reference	Description	Quantity	Possible sources and notes
PCB		Radio-86RK PCB	1	Buy from my Tindie store: Radio-86RK - PCB or order from a PCB manufacturer of your choice using provided Gerber or KiCad files
Capacitor	C1 - C32	0.1 uF, MLCC, 5 mm Pitch	32	Mouser 594-K104K15X7RF53H5
Capacitor	C33 - C38	47 uF, 25V, Electrolytic or Organic Polymer	6	Mouser 80-A750EK476M1EAAE40
Capacitor	C39	0.22 uF, MLCC, 5 mm Pitch	1	Mouser 810-FG24X7R1H224KNT0
Capacitor	C40	22 nF, MLCC, 5 mm Pitch	1	Mouser 810-FG28X7R1H223KNT0
Capacitor	C41	10 nF, MLCC, 5 mm Pitch	1	Mouser 810-FG28X7R1H103KNT0
Capacitor	C42	2.2 nF, MLCC, 5 mm Pitch	1	Mouser 810-FG28X7R1H222KNT0
Capacitor	C43	1 nF, MLCC, 5 mm Pitch	1	Mouser 810-FG28C0G1H102JNT6
Capacitor	C44	10 pF, MLCC, 5 mm Pitch	1	Mouser 810-FG28C0G1H100DNT00
Diode	D1 - D9	1N4148	9	Mouser 512-1N4148
LED	D10	LED Indicator, 3 mm, Green	1	Mouser 630-HLMP-1503-C0002
LED	D11	LED Indicator, 3 mm, Yellow	1	Mouser 630-HLMP-1401
Polyfuse	F1	1.1A, 5 mm Pitch	1	Mouser 576-16R110BU
Connector	JP1, JP2	4 pin header, 2.54 mm Pitch	2	Mouser 649-68000-204HLF
Connector	JP1, JP2	Jumper, 2.54 mm Pitch	4	Mouser 806-SX1100-B)
Connector	J1	RCA Phono connector, Yellow	1	Mouser 490-RCJ-014
Connector	J2	DC Power Jack, 2mm	1	Mouser 806-KLDX-0202-A
Connector	J3	8 pin friction lock connector	1	Mouser 571-6404568
Connector	J4	DIN 8-pos, Right Angle, PCB mount	1	Mouser 490-SDF-80J
Connector	J5	Sub-D DE9M, Right Angle, PCB mount	1	Mouser 523-L717SDE09P1ACH3R
Connector	J6	13x2 pin header, shrouded	1	Mouser 517-30326-6002
Connector	J7	20x1 pin socket	1	Mouser 517-929850-01-20-RB. Note: Optional, for extension board connection
Transistor	Q1, Q2	2N3904	2	Mouser 512-2N3904TA
Resistor	R1	33 ohm	1	Mouser 660-CF1/4CT52R330J
Resistor	R2	75 ohm	1	Mouser 660-CF1/4CT52R750J
Resistor	R3	150 ohm	1	Mouser 660-CF1/4CT52R151J
Resistor	R4	330 ohm	1	Mouser 660-CF1/4CT52R331J
Resistor	R5	1.5 k	1	Mouser 660-CF1/4CT52R152J
Resistor	R6 - R13	1 k	8	Mouser 660-CF1/4CT52R102J
Resistor	R14	2.4 k	1	Mouser 660-CF1/4CT52R242J
Resistor	R15	12 k	1	Mouser 660-CF1/4CT52R123J
Resistor Array	RN1	10 k, SIP10	1	Mouser 652-4610X-1LF-10K
Resistor Array	RN2 - RN4	4.7 k, SIP6	3	Mouser 652-4606X-1LF-4.7K
Speaker	SP1	12 mm speaker	1	Mouser 665-AT-1224TWTR
Keyboard Switch	SW1 - SW67	Cherry MX Blue (Clicky)	67	Mouser 540-MX1A-E1NW
Switch Leveling Kit	SW11, SW64	Leveling kit for MX 1x2, 1x2.25, 1x2.75	2	Mouser 540-G99-0742
Switch Leveling Kit	SW64	Leveling kit for MX 1x8	1	Mouser 540-G99-0226 Note: Use the wire from this part and one of 540-G99-0742 to build a through hole leveling kit for the spacebar
Tactile Switch	SW68	6 mm Tactile Switch Right Angle	1	Mouser 653-B3F-3152
Switch Keycap	SW68	4 x 4 mmm Tactile Switch Key Cap, Orange	1	Mouser 653-B32-1020
Integrated Circuit	U1	Intel 8080A / КР580ВМ80А, CPU	1	Unicorn Electronics 8080A, Jameco 52046
Integrated Circuit	U2	Intel 8224 / КР580ГФ24, Clock Generator	1	Unicorn Electronics 8224
Integrated Circuit	U3	Intel 8251А / КР580ВВ51А, USART	1	Unicorn Electronics 8251A
Integrated Circuit	U4	Intel 8253 / КР580ВИ53, PIT	1	Unicorn Electronics 8253, Mouser 968-CP82C54Z
Integrated Circuit	U5, U6	Intel 8255А / КР580ВВ55А, PPI	2	Unicorn Electronics 8055A, Mouser 968-CP82C55A-5Z, Jameco 52732
Integrated Circuit	U7	Intel 8257 / КР580ВТ57, DMA Controller	1	Unicorn Electronics 8257
Integrated Circuit	U8	Intel 8275 / КР580ВГ75, CRT Controller	1	Unicorn Electronics 8275, Jameco 52821
Integrated Circuit	U9	AS6C62256, SRAM 32Kx8	1	Mouser 913-AS6C62256-55PCN, Unicorn Electronics 62256LP
Integrated Circuit	U10, U11	2716 / КР573РФ5, 2Kx8 EPROM	2	Mouser 556-AT28C64B15PU, Unicorn Electronics 2716. Note: 2716, 2732, 2764, 27C64 EPROMs, or 28C64 EEPROMs can be used
Integrated Circuit	U12	74LS373/К555ИР22, 8-bit Latch, 3-state outputs	1	Mouser 595-SN74LS373N
Integrated Circuit	U13	74198/К155ИР13, 8-bit Shift Register	1	Unicorn Electronics 74198
Integrated Circuit	U14	74LS138/К555ИД7, Decoder 3 to 8 active low outputs	1	Mouser 595-SN74LS138N, Unicorn Electronics 74LS138
Integrated Circuit	U15	7492/К155ИЕ4, Divide by 12 counter	1	Mouser 595-SN74LS92N, Unicorn Electronics 74LS92
Integrated Circuit	U16	7486/К155ЛП5, Quad 2-input XOR	1	Mouser 595-SN74LS86AN, Unicorn Electronics 74LS86
Integrated Circuit	U17	7474/К155ТМ2, Dual D Flip-flop, Set & Reset	1	Mouser 595-SN74LS74AN, Unicorn Electronics 74LS74
Integrated Circuit	U18	7408/К155ЛИ1, Quad 2-input AND	1	Mouser 595-SN74LS08N, Unicorn Electronics 74LS08
Integrated Circuit	U19	7404/К155ЛН1, Hex Inverter	1	Mouser 595-SN74LS04N, Unicorn Electronics 74LS04
Integrated Circuit	U20	7400/К155ЛА3, Quad 2-input NAND	1	Mouser 595-SN74LS00N, Unicorn Electronics 74LS00
Integrated Circuit	U21	TL071/К140УД6, Operational Amplifier	1	Mouser 595-TL071IP
Integrated Circuit	U22	SN75154N/К170УП2В, Quad RS-232 Receiver	1	Mouser 595-SN75154N, Unicorn Electronics 75154
Integrated Circuit	U23, U24	SN75150P/К170АП2, Dual RS-232 Driver	2	Mouser 595-SN75150P, Unicorn Electronics 75150
Integrated Circuit	U25	LM7905/КР1179ЕНВ, Negative 5V 1A Linear Regulator	1	Mouser 926-LM7905CT-NOPB, Unicorn Electronics 7905T
DC-DC Converter	U26	IZ0512, +/-12V +/-125mA, 4.5V-9V input	1	Mouser 209-IZ0512S
Integrated Circuit	U27	DS1233-5, CPU Supervisory Circuit	1	Mouser 700-DS1233-5T&R
Crystal	Y1	16 MHz, Series, HC-49U	1	Mouser 774-ATS160-E
IC Socket	U1, U5, U6, U7, U8	40 pin DIP	5	Mouser 649-DILB40P223TLF, 517-4840-6000-CP
IC Socket	U3, U9, U10, U11	28 pin DIP	4	Mouser 649-DILB28P223TLF, 517-4828-6000-CP
IC Socket	U4, U13	24 pin DIP	2	Mouser 649-DILB24P-223TLF, 517-4824-6000-CP
IC Socket	U12	20 pin DIP	1	Mouser 649-DILB20P-223TLF, 517-4820-3000-CP
IC Socket	U2, U14, U22	16 pin DIP	3	Mouser 649-DILB16P-223TLF, 517-4816-3000-CP
IC Socket	U15 - U20	14 pin DIP	6	Mouser 649-DILB14P-223TLF, 517-4814-3000-CP
IC Socket	U21, U23, U24	8 pin DIP	3	Mouser 649-DILB8P223TLF, 517-4808-3000-CP

Memory Map

• 0000h - 7FFFh - SRAM
  • 7600h - 7FFFh - Display buffer and monitor variables
• 8000h - 8FFFh - 8255A PPI (Keyboard, Cassette recorder, Sound control)
  • 8000h - Channel A data
  • 8001h - Channel B data
  • 8002h - Channel C data
  • 8003h - Control word
• 9000h - 9FFFh - 8253 Timer (USART Clock, Sound)
  • 9000h - Channel 0 count
  • 9001h - Channel 1 count
  • 9002h - Channel 2 count
  • 9003h - Control word
• 0A000h - 0AFFFh - 8255A PPI (Parallel Interface)
  • 0A000h - Channel A data
  • 0A001h - Channel B data
  • 0A002h - Channel C data
  • 0A003h - Control word
• 0B000h - 0BFFFh - 8251A USART
  • 0B000h - Data register
  • 0B001h - Command register
• 0C000h - 0CFFFh - 8275 CRT Controller
• 0D000h - 0DFFFh - Unused
• 0E000h - 0EFFFh - 8257 DMA Controller (write only)
• 0E000h - 0FFFFh - Monitor EPROM (read only)

Firmware Documentation

Monitor

Monitor Commands

• Memory Operations
  • D<Start_Address>,<End_Address> - Display memory content in hexadecimal
  • L<Start_Address>,<End_Address> - Display memory content in ASCII
  • F<Start_Address>,<End_Address>,<Value> - Fill memory with the specified value
  • M<Address> - Modify memory content
  • T<Start_Address>,<End_Address>,<Destination_Start_Address> - Copy memory block to destination
  • C<Start_Address>,<End_Address>,<Destination_Start_Address> - Compare memory block with destination
  • S<Start_Address>,<End_Address>,<Value> - Search memory for a value
  • R<ROM_Start_Address>,<ROM_End_Address>,<Destination_Start_Address> - Read from the ROM connected to the Parallel interface to memory
• Run Control
  • G<Start_Address>[,End_Address] - Run code, optionally stop at the specified address
  • X - Display and modify registers
• Cassette Input/Output
  • O<Start_Address>,<End_Address>[,Speed] - Write memory to cassette. Default speed is 1Dh / 1200 bps
  • I[Offset][,Speed] - Read data from to cassette memory at specified offset

Monitor Subroutines:

• 0F803h - Keyboard input
  • Input: None
  • Output: A - character code read from keyboard
• 0F806h - Cassette input
  • Input: A=0FFh - with sync; A=08h - no sync
  • Output: A - data read from cassette
• 0F809h - Print character to screen
  • Input: C - character to print
• 0F80Ch - Cassette output
  • Input: C - data to write
• 0F812h - Query keyboard
  • Output: A=00h - key not pressed; A=0FFh - key pressed
• 0F815h - Print to screen in hex
  • Input: A - data to print
• 0F818h - Print string
  • Input: HL - string address
• 0F81Bh - Get key
  • Output: A=0FFh - key not pressed; A=0FEh - Rus/Lat; otherwise A - key code
• 0F81Eh - Get cursor position
  • Output: H - row, L - column
• 0F821h - Read character from screen at current cursor position
  • Output: A - char read from screen
• 0F824h - Read from cassette
  • Input: HL - offset of memory buffer to store data to
  • Output: HL - start; DE - end; BC - checksum

Release Notes

Changes

• Version 1.4

  • Change keyboard layout to QWERTY
  • Add the J7 extension connector
  • Add support for 2732, 2764 and 27C64 EPROMs and 28C64 EEPROM.

• Version 1.3

  • Fix issues from version 1.1 and version 1.2:
    • Use key labels "Ь X" and "СС SHIFT" on top silkscreen
    • Video signal generation circuit: use R2 = 75 Ohm and R5 = 1.5 kOhm

• Version 1.2

  • Add F5 key
  • Add copyright year on the top silkscreen

• Version 1.1

  • Fix all known issues of version 1.0
  • Use DS1233-5 mircoprocessor supervisor to generate reset signal
  • Implement reverse video attribute

• Version 1.0

  • Initial version

Known Issues

• Version 1.3

  • No known issues

• Version 1.2

  • Top silkscreen: "Ь" and "X" key labels are swapped
  • Top silkscreen: More correct translation for "СС" is "SHIFT"
  • Video signal generation: Produced video Vpp and the backporch levels are a bit too high. Use R2 = 75 to 100 Ohm, and R5 = 1.5 kOhm for proper video signal levels (Reported by Martin Lukasek)

• Version 1.1

  • Top silkscreen: "Ь" and "X" key labels are swapped
  • Top silkscreen: More correct translation for "СС" is "SHIFT"
  • Top silkscreen: No copyright year
  • Video signal generation: Produced video Vpp and the backporch levels are a bit too high. Use R2 = 75 to 100 Ohm, and R5 = 1.5 kOhm for proper video signal levels (Reported by Martin Lukasek)

• Version 1.0

  • 8224 (U2) should use DIP-16 footprint
  • Down and Right buttons swapped
  • Reset RC does not provide enough time for the system to properly reset at power-on