This article is written by Jeff M. Nay, about his experiments to restore a KIM-1 to working order, testing the 6530-002 RRIOT with his own KIM-1.
The challenge was to address the second 6530-002 in this setup at another address then the onboard 6530-002 RRIOT.
The experiment was a success, the 6530-002 is indeed in a bad state, the ROM is corrupt and it had to be replaced.

The KIM-1, from a friend, was in a bad state. The repair was a success also. He was able to get this old KIM-1 working again, after only having to replace, the 6502 CPU, the 6530-002 RRIOT Chip with a Corsham 6530 Replacement board, all 8 Memory Chips and the U17 7406 inverter.

Read more in the group: KIM-1 – Google Groups

Breadboard Test for 6530-002

Attach Breadboard to working KIM-1, using Expansion Port and using K4 and K2 from Application Port (Corsham Application Board)
NOTE: Turn all SW1 switches on CORSHAM Board Off (Or data will repeat at K1,K2,K3,K4)

I started by wiring the data lines on the 6530 to the expansion board pins 15-8.
Then the address lines to pins A-L.
Now it is just a matter of wiring the control lines correctly.

• I have phase 2, pin 3 of the 6530 going to pin U of the Expansion board (Yellow)
• I have pin 4 (RSO) of the 6530 going to (K4) of my Corsham Application Board – (Don’t forget pull up resistor) (Blue)
• I have RES pin 16 of the 6530 wired to pin 7 (RST) of the Expansion board
• I have pin 18, (CS1) on the 6530. Going to (K2) of my Corsham Application Board – (Don’t forget pull up resistor) (White)
• I have Power going to pin 20 and Gnd going to pin 1

You should be able to read ROM at $1000

Looking below at the data sheet, where the address of the I/O and RAM are determined by A9-A6. This means it is not hard set for $1700 or $1740.
K5 ($1400) + A9-A6 determines where the IO of both 6530s will start and end.

I ended up using K2, which starts at $0800 + A9-A6 means my I/O registers should start at $0B40 for the 6530-002 or $0B00 for the 6530-003
I also use K4 for the ROM section of the 6530-002 which starts the ROM section at $1000

This is the ROM of 6530-002 breadboard being accessed at $1000 (85)

The now working KIM-1:

The Chessmate is a 6530 – KIM-1 like computer. Keyboard, LED display are used as in the KIM-1. Peter Jennings, who designed this chess computer with Commodore, build upon his Microchess 1. from the KIM-1, and used the extra ROM space to enhance it to Microchess 1.5: more chess features, a chess clock, sounds, dedicated keys, status LEDs.

The 6530-024 delivers the I/O and timer and RAM used by the Chessmate, the RRIOT ROM is used by the main ROM as a Chess openings book.

It will not be that difficult to ‘clone’ this chess computer with the information here. A 6532 can easily take the role of the 6530. A 6502 instead of a 6504, some SRAM, a 2732 or similar ROM. The ROMs are dumped, see below.

On this page:

• Technical Specifications
• Manuals, documents and ROM dumps
• Notes on the 653- 024 RRIOT
• Opening book deciphered
• Chessmate emulators
• Photos of my Chessmate, others Chessmates and other vesions

My Chessmate

Technical specifications

• MOS MPS 6504 1 MHz 4 KB ROM 320 bytes RAM total
• 6530-0024 RRIOT (of which I/O lines, timer and 64 bytes RAM are used, ROM has data as chess openings book
• 256 SRAM (2x 2111)
• 4K ROM (6332), early models have 2x 2K ROMs
• Display: Four 7 Segment LED type (which indicates either the move or the time)
• 19 membrane keys
• LEDs for Check, Chessmate, or whether the computer is playing black or white
• Eight skill levels
• Piezo loudspeaker for 14 Electronic sounds
• Built-in chess clock
• The computer has 32 International standard openings in its memory and tries to follow them for 16 moves
• Chessmate plays black or white
• Can verify position of pieces at any stage of the game
• En passant and castling
• Playing strength (DWZ/ELO): ca. 1050

Related, identical specifications and hardware, and the same software, images below:

• Novag Chess Champion MK II (A)
• Novag Chess Champion MK II (B)
• TEC Schachcomputer

Memory map (deduced from disassembled source and hardware schematic, note that for the 6504 this is collapsed to the smaller address space 0000-1FFF. The software is written for the 6502 though!
$0000 – $01FF RAM 256 bytes, stack and zeropage mirrored
$8B00 – RRIOT I/O
$8B80 – RRIOT RAM 64 byte
$8C00 – $8FFF RRIOT ROM
$F000 – $FFFF Main ROM

Manuals and ROM dumps

	Commodore Chessmate manual
	Another Commodore Chessmate manual
	ROMs of early Commodore Chessmate, in two 2K parts and later main 4k ROM and the 630 024 RRIOT ROM
	ROMs of Novag Chess Champion MK II (Main 4k ROM and 630 024 RRIOT ROM, identical to Commodore ROMs!
	Novag Chess Champion MKII manual
	Partially commented source by me of the ROM of the Chessmate

Notes on the 6530 024 RRIOT

Michael Gardi helped me discover the following about the use of the RRIOT in the Chessmate, comments added to the source:
1. The timer is used for the random selection of openings.
CKINT = $8B0E
F38D AD 0E 8B LDA CKINT
2. The openings are stored in the RRIOT 1K ROM at $8C00
3. The RRIOT Timer is also used to implement the CHESSmate chess clock mode, see the source.

Opening book deciphered

The Chessmate chooses at random an opening from the opening book, which is in the 1K ROM of the 6530 024 RRIOT.
The first thing that pops out is that 28 of the 32 openings start with either D2-D4 (10) or E2-E4 (18). That explains the very high percentage of the time that these occur when openings are randomly selected. The Operation Instructions explicitly states that CHESSmate chooses one opening at random and tries to follow it for 16 moves

Micheal Gardi deciphered the coding of the openings:
There are 32 bytes for each opening representing 16 moves. Even bytes represent start positions and odd bytes represent end positions. A pair of bytes make a move. Moves alternate between white and black starting with white. Each byte represents a position on the chess board. The high nibble is the rank (row 1-8) and the low nibble the is the file (column A-H).

col_table = ['H','G','F','E','D','C','B','A']
row_table = ['1','2','3','4','5','6','7','8']

with open("Opening Book.bin", 'rb') as f:
    buffer = f.read()
   
    # For each line.
    ent_file = []
    even = 0
    address = 0x8C00
    for i in range(0,len(buffer),2):
        if i % 32 == 0:
            ent_file.append("\n")
            ent_file.append(hex(address))
            ent_file.append(": ")
            address += 32
        # Assume bytes are contiguous.
        if (even % 2) == 0:
            ent_file.append(col_table[buffer[i]&0x0F]+row_table[buffer[i]>>4]+"-"+
                            col_table[buffer[i+1]&0x0F]+row_table[buffer[i+1]>>4] +", ")   
        else:
            ent_file.append(col_table[7-(buffer[i]&0x0F)]+row_table[7-(buffer[i]>>4)]+"-"+
                            col_table[7-(buffer[i+1]&0x0F)]+row_table[7-(buffer[i+1]>>4)] +", ")
        even += 1     
    ent_file.append('\n')
    
    # Output the result.
    with open("Opening Book Dump.txt", 'w') as f:
        f.write(''.join(ent_file))

Running that code delivers this

8c00: E2-E4, E7-E5, G1-F3, B8-C6, B1-C3, G8-F6, F1-B5, F8-B4, E1-G1, E8-G8, D2-D3, D7-D6, C1-G5, B4-C3, B2-C3, D8-E7
8c20: D2-D4, D7-D5, C2-C4, D5-C4, G1-F3, G8-F6, E2-E3, E7-E6, F1-C4, C7-C5, E1-G1, A7-A6, D1-E2, B8-C6, B1-C3, C5-D4 
8c40: F2-F4, D7-D5, E2-E3, G8-F6, G1-F3, C7-C5, B2-B3, E7-E6, C1-B2, B8-C6, F1-B5, C8-D7, E1-G1, F8-D6, D2-D3, D8-C7 
8c60: E2-E4, E7-E5, F1-C4, G8-F6, D2-D4, E5-D4, G1-F3, F6-E4, D1-D4, E4-F6, C1-G5, F8-E7, B1-C3, C7-C6, E1-C1, D7-D5 
8c80: E2-E4, C7-C5, G1-F3, B8-C6, D2-D4, C5-D4, F3-D4, G8-F6, B1-C3, D7-D6, F1-E2, G7-G6, C1-E3, F8-G7, E1-G1, E8-G8 
8ca0: E2-E4, C7-C5, B1-C3, B8-C6, G2-G3, G7-G6, F1-G2, F8-G7, D2-D3, E7-E6, C1-E3, D7-D6, G1-E2, C6-D4, E1-G1, G8-E7
8cc0: E2-E4, E7-E5, G1-F3, B8-C6, F1-C4, F8-C5, C2-C3, G8-F6, D2-D4, E5-D4, C3-D4, C5-B4, B1-C3, F6-E4, E1-G1, E4-C3 
8ce0: G1-F3, G8-F6, C2-C4, C7-C5, D2-D4, C5-D4, F3-D4, E7-E6, B1-C3, F8-B4, C1-D2, E8-G8, E2-E3, B8-C6, F1-E2, D7-D5 
8d00: E2-E4, E7-E5, G1-F3, G8-F6, F3-E5, D7-D6, E5-F3, F6-E4, D2-D4, D6-D5, F1-D3, F8-D6, E1-G1, E8-G8, C2-C4, C7-C6 
8d20: D2-D4, G8-F6, C2-C4, E7-E6, G2-G3, D7-D5, F1-G2, D5-C4, D1-A4, B8-D7, A4-C4, A7-A6, G1-F3, B7-B5, C4-C6, A8-A7
8d40: E2-E4, G8-F6, E4-E5, F6-D5, D2-D4, D7-D6, C2-C4, D5-B6, F2-F4, D6-E5, F4-E5, B8-C6, C1-E3, C8-F5, B1-C3, E7-E6 
8d60: D2-D4, F7-F5, C2-C4, E7-E6, G1-F3, G8-F6, G2-G3, F8-E7, F1-G2, E8-G8, E1-G1, D7-D5, B1-C3, C7-C6, C1-F4, D8-E8 
8d80: E2-E4, E7-E5, G1-F3, B8-C6, F1-C4, G8-F6, D2-D4, E5-D4, E1-G1, F6-E4, F1-E1, D7-D5, C4-D5, D8-D5, B1-C3, D5-A5 
8da0: D2-D4, G8-F6, C2-C4, E7-E6, B1-C3, F8-B4, D1-C2, B8-C6, G1-F3, D7-D6, C1-D2, E6-E5, A2-A3, B4-C3, D2-C3, D8-E7 
8dc0: E2-E4, B8-C6, D2-D4, D7-D5, E4-D5, D8-D5, G1-F3, E7-E5, B1-C3, F8-B4, C1-E3, C8-G4, F1-E2, E8-C8, E1-G1, D5-A5 
8de0: D2-D4, D7-D5, C2-C4, E7-E6, B1-C3, G8-F6, C1-G5, B8-D7, G1-F3, F8-B4, C4-D5, E6-D5, E2-E3, C7-C5, F1-D3, D8-A5
8e00: D2-D4, D7-D5, C2-C4, C7-C6, G1-F3, G8-F6, B1-C3, D5-C4, A2-A4, C8-F5, F3-E5, B8-D7, E5-C4, D8-C7, G2-G3, E7-E5
8e20: E2-E4, E7-E5, G1-F3, B8-C6, F1-B5, D7-D6, D2-D4, C8-D7, B1-C3, G8-F6, E1-G1, F8-E7, F1-E1, E5-D4, F3-D4, E8-G8 
8e40: D2-D4, D7-D5, C2-C4, E7-E6, B1-C3, C7-C5, C4-D5, E6-D5, G1-F3, B8-C6, G2-G3, G8-F6, F1-G2, C5-D4, F3-D4, F8-C5 
8e60: E2-E4, E7-E5, G1-F3, B8-C6, F1-B5, A7-A6, B5-C6, D7-C6, D2-D4, E5-D4, D1-D4, D8-D4, F3-D4, C8-D7, B1-C3, E8-C8 
8e80: D2-D4, C7-C5, D4-D5, D7-D6, C2-C4, G7-G6, B1-C3, F8-G7, E2-E4, G8-F6, F1-E2, E7-E6, C1-G5, E8-G8, G1-F3, E6-D5 
8ea0: E2-E4, E7-E5, G1-F3, B8-C6, D2-D4, E5-D4, F3-D4, G8-F6, B1-C3, F8-B4, D4-C6, B7-C6, F1-D3, D7-D5, E4-D5, C6-D5 
8ec0: D2-D4, G8-F6, C2-C4, G7-G6, B1-C3, F8-G7, E2-E4, D7-D6, F2-F3, E7-E5, D4-D5, E8-G8, C1-G5, H7-H6, G5-E3, F6-H5 
8ee0: E2-E4, C7-C6, D2-D4, D7-D5, B1-C3, D5-E4, C3-E4, C8-F5, E4-G3, F5-G6, H2-H4, H7-H6, G1-F3, B8-D7, F1-D3, G6-D3 
8f00: D2-D4, G8-F6, C2-C4, E7-E6, G1-F3, B7-B6, G2-G3, C8-B7, F1-G2, F8-E7, E1-G1, E8-G8, B1-C3, F6-E4, D1-C2, E4-C3 
8f20: C2-C4, G8-F6, B1-C3, E7-E6, E2-E4, C7-C5, G1-F3, B8-C6, D2-D4, C5-D4, F3-D4, F8-B4, D4-C6, D7-C6, D1-D8, E8-D8 
8f40: E2-E4, E7-E5, G1-F3, B8-C6, F1-B5, G8-F6, E1-G1, F6-E4, D2-D4, F8-E7, D1-E2, E4-D6, B5-C6, B7-C6, D4-E5, D6-B7 
8f60: E2-E4, E7-E6, D2-D4, D7-D5, B1-C3, G8-F6, C1-G5, F8-E7, E4-E5, F6-D7, G5-E7, D8-E7, D1-D2, E8-G8, F2-F4, C7-C5
8f80: E2-E4, E7-E5, D2-D4, E5-D4, D1-D4, B8-C6, D4-E3, G8-F6, B1-C3, F8-B4, C1-D2, E8-G8, E1-C1, F8-E8, F1-C4, D7-D6 
8fa0: E2-E4, E7-E5, D2-D4, E5-D4, C2-C3, D4-C3, F1-C4, C3-B2, C1-B2, G8-F6, B1-C3, B8-C6, G1-F3, F8-B4, D1-C2, D7-D6 
8fc0: C2-C4, E7-E5, B1-C3, G8-F6, G1-F3, B8-C6, E2-E3, D7-D5, C4-D5, F6-D5, F1-B5, D5-C3, B2-C3, F8-D6, D2-D4, C8-D7 
8fe0: E2-E4, E7-E5, G1-F3, B8-C6, F1-B5, A7-A6, B5-A4, B7-B5, A4-B3, C6-A5, B3-F7, E8-F7, F3-E5, F7-E7, D2-D4, G8-F6

Chessmate emulator by Stephen Crane

An emulator with the look and feel of the Chessmate by Michael Gardi

Images of Chessmates

My Commodore Chessmate.

My Chessmate

Photo by Commodore International Historical Society on twitter @commodoreihs

Photo by Commodore International Historical Society on twitter @commodoreihs

On this early Chessmate two ROMs were used, each 2K. The TTL IC on the top right was added manually and wire wrapped, the wires running from it to the ROM selection inputs.

Boxes

Photo by Michael Gardi

Novag Chess Champion MK II A and B