LB-MEM-02

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LB-MEM-02 P1660-720px.jpg


Features

  • 32KB SRAM
  • 16KB EPROM
    • Headers to select PROM bank
  • Connects to Address/Data and Memory control lines
  • 50x75mm card

Design

SRAM

LB-MEM-02-SRAM.PNG

EPROM

LB-MEM-02-PROM.PNG

  • LB-65CXX-01 card has 16 KB PROM from 0xC000-0xFFFF
  • LB-6802-01 card has 16 KB PROM from 0xC000-0xFFFF
  • LB-6809-01 card has 16 KB PROM from 0xC000-0xFFFF
  • LB-Z80-01 card has 8KB PROM from 0x0000-0x1FFF (upper 8KB is not used)

Parts/Jumpers

  • Square pin is pin 1

LB-MEM-02 REV1 MECH Ann.png

27C256/27C512 EPROMs

  • Card has a 16KB size from the CPU
  • 27C256 (32KB) and 27C512 (64KB) Flash EPROMs are commonly available
  • Jumpers allow firmware banks to be selected
    • 2 banks in 27C256
    • 4 banks in 27C512
EPROM SIZE BANKS J6(A15/P1) J2(A14/P27) BANK # LOAD OFFSET
27C128 16KB 1 2-3 (GND) 2-3 (GND) 1 0x0000
27C256 32KB 2 2-3 (GND) 1-2 (VCC) 1 0x0000
27C256 32KB 2 2-3 (GND) 2-3 (GND) 2 0x4000
27C512 64KB 4 2-3 (GND) 2-3 (GND) 1 0x0000
27C512 64KB 4 2-3 (GND) 1-2 (VCC) 2 0x4000
27C512 64KB 4 1-2 (VCC) 2-3 (GND) 3 0x8000
27C512 64KB 4 1-2 (VCC) 1-2 (VCC) 4 0xC000

LB-MEM-02 EPROM 27C128 256 512.png

Backplane Connector

LB-MEM-02-BKPL.PNG

Mechanicals

Rev 3

Rev 2

LB-MEM-02 Rev2 MECH.PNG

Rev 1

LB-MEM-02 REV1 MECH.PNG

Checkout

Rev 3

  • Adds PWR and GND on U1 (74HC04)
  • Adds electrolytic cap footprint

Rev 2

  • Flips 74HC04 orientation
  • Missing PWR and GND on U1 (74HC04)
  • Tested with LB-6809-01 card
    • Works

Rev 1

  • Missing PWR and GND on U1 (74HC04)
    • Added PWR and GND wires to nearest pins with PWR and GND
  • SRAM passes in TL866 in SRAM test mode
  • Test using ramLoop.asm software

Assembly Sheet

Rev 3

Rev 1