LB-68B50-02

Features

• Serial/Parallel I/O Card
• 68B50 UART
• 1.8432 MHz oscillator
  • Baud Rate Clock (115,200 baud oscillator)
• Control PLD
• 100x50mm card

Design

ACIA

• 68B50 UART
• Baud Rate Clock (115,200 baud oscillator)

PLD

• Customize PLD per CPU type and to match memory map
  • Can be used to support multiple 6850 cards
• ATF16V8B part
• TL866ii Plus Programmer

LB-68B50-02_6XXX_PLD Listing

• 6XXX (6502, 6802, 6809 specific)

Name       LB-68B50-02_6XXX_PLD;
Partno     ATF16V8B;
Date       09/20/24;
Revision   01;
Designer   DOUG G;
Company    LAND BOARDS LLC;
Assembly   LB-68B50-02_6XXX_U2;
Location   Rustbelt, US;
Device     G16V8;

/*
	68B50 Control for LB-6809-01, LB-6802-01, and LB-65CXX CPU boards
	0x8000-0xBFFF - 16KB I/O space
*/

/* Control inputs */
PIN    1   = CPUA15;
PIN    2   = CPUA14;
PIN    3   = CPUA13;
PIN    4   = CPUA12;
PIN    5   = CPUA11;
PIN    6   = CPUA10;
PIN    7   = CPUA1;
PIN    8   = CPUA0;
PIN    9   = !IOCS;	/* IOCS is IO space decoded on all CPU cards 	*/
PIN    11   = VDA;	/* Not used in any version	*/
PIN    12   = VPB;	/* VPB is enable on 6802, 6809 AND 6502 (Rev 2 rwk) CPUs */
PIN    14   = !IORQ;	/* IORQ* is enable on Z80 cards	*/

/* Address Decode and Chip Select outputs */
PIN    16  = ACIACS1;
PIN    17  = ACIACS0;
PIN    18  = ACIARS;
PIN    19  = ACIAE;

ACIACS1 = CPUA15 & !CPUA14 & IOCS;

ACIACS0 = CPUA15 & !CPUA14 & IOCS;

ACIARS = CPUA0;

ACIAE = CPUA15 & !CPUA14 & IOCS & VPB;

LB-68B50-02_Z80_PLD PLD Listing

Name       LB-68B50-02_Z80_PLD;
Partno     ATF16V8B;
Date       09/19/24;
Revision   01;
Designer   DOUG G;
Company    LAND BOARDS LLC;
Assembly   LB-6850-02_U2;
Location   Rustbelt, US;
Device     G16V8;

/*
	68B50 Control for Z80 CPU board
*/

/* Control inputs */
PIN    1   = CPUA15;
PIN    2   = CPUA14;
PIN    3   = CPUA13;
PIN    4   = CPUA12;
PIN    5   = CPUA11;
PIN    6   = CPUA10;
PIN    7   = CPUA1;
PIN    8   = CPUA0;
PIN    9   = !IOCS;
PIN    11  = VDA;
PIN    12  = VPB;
PIN    13  = !IORQ;

/* Address Decode and Chip Select outputs */
PIN    16  = ACIACS1;
PIN    17  = ACIACS0;
PIN    18  = ACIARS;
PIN    19  = ACIAE;

ACIACS1 = IOCS & IORQ;

ACIACS0 = IOCS & IORQ;

ACIARS = CPUA0;

ACIAE = IOCS & IORQ;

J2 - FTDI Header)

• 5V levels
• Pinout

1. GND
2. CTS (in)
3. VCC
4. TX (out)
5. RX (in)
6. RTS (out)

Backplane

Mechanicals

Rev 2

Rev 1

Checkout

Rev 2 Changes

• Fixed IOCS* to be on J1-38
• Fixed IORQ signal
  • Inv on one end but not on the other end on schematic
• Added config jumper J3 into PLD (U2-14) to allow for 2 configs
  • 6502, 6802, 6809 jumper removed
  • Z80 jumper installed
• Add LED with resistor to U2-15
• Moved Osc down a bit

Rev 1 Checkout

IOCS* is on wrong pin

• It is on J1-38 on the Rev 1 PCB
• IOCS* should be on pin J1-37
• Rework
  • Add wire J1-37 to U2-13
  • Cut trace near J1-38

• Rev 1 before

• Fixed on Rev 2 PCB

Missing IORQ signal

• Inverted on one end but not on the other end on schematic
• Rev 1

• Rev 2

• Rework
  • Add wire U2-13 to J1-51 (Z80)

Assembly Sheet

Rev 2

• Interactive BOM

Rev 1

• Interactive BOM