LB-68B50-02

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Lb-6850-01 P1672-720PX.jpg

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)

LB-68B50-02 ACIA-Rev2.PNG

PLD

LB-68B50-02 U2 PLD.PNG

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)

LB-68B50-02 J2 FTDI.PNG

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

Backplane

LB-68B50-02 J1 Backplane.PNG

Mechanicals

Rev 2

LB-68B50-02 Rev2 MECHS.PNG

Rev 1

LB-68B50-02 Rev1 MECHS.PNG

Checkout

Rev 2 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
  • Add LED with resistor to U2-15
  • Moved Osc down a bit

LB-6850-02 FRONT REV2(BLK).png

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

LB-68B50-02 J1-38 Rework.PNG

  • Rev 1 before

LB-68B50-02 NP Errors-Rev2.PNG

  • Fixed on Rev 2 PCB

LB-68B50-02 NP Fixed-Rev2.PNG

Missing IORQ signal

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

LB-68B50-02 U2 IORQ Before.PNG

  • Rev 2

LB-68B50-02 U2 IORQ After.PNG

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

Mechanicals

Assembly Sheet

Rev 2

Rev 1