This document is for the baby-sized (13.3" x 8.5") Baby Gemini 486SX-25 motherboard. It is also known as the "Upgradeable" board because it can accommodate the Intel OverDrive CPU. The part number for this board is 09-00145-xx. It's identifying features are: an LED between expansion slots #5 and #6; eight 16-bit expansion slots; four sockets for SIMMs (using 72-pin SIMMs); one proprietary 80-pin SIMM socket which accommodates a Micronics External Cache Card. The bus speed for this motherboard is fixed at 8MHz. +=============================+ + + + MOTHERBOARD SWITCH SETTINGS + + + + * = Default setting + +=============================+ SW1 --- 1 Memory size (see below) 2 Memory size (see below) 3 Memory size (see below) 4 Memory size (see below) 5 Reserved *Off 6 Reserved *Off 7 Reserved *Off 8 Reserved *On DIP switch settings for memory size =================================== Memory Banks DIP Switch 2 ----------------------------------------------- MB 0 1 2 3 S1 S2 S3 S4 ---- ---- ---- ---- ---- ---- ---- ---- ---- 4MB 4M ON ON ON ON 8MB 4M 4M OFF ON ON ON 12MB 4M 4M 4M ON OFF ON ON 16MB 4M 4M 4M 4M OFF OFF ON ON 16MB 16M ON ON OFF ON 20MB 4M 16M ON ON OFF OFF 24MB 4M 4M 16M ON OFF ON OFF 28MB 4M 4M 4M 16M OFF ON ON OFF 32MB 16M 16M OFF ON OFF ON 36MB 4M 16M 16M ON OFF OFF OFF 40MB 4M 4M 16M 16M OFF OFF ON OFF 48MB 16M 16M 16M ON OFF OFF ON 52MB 4M 16M 16M 16M OFF OFF OFF OFF 64MB 16M 16M 16M 16M OFF OFF OFF ON In the table above, 4M indicates that one 1Mx36 SIMM is installed in the socket, 16M indicates that one 4Mx36 SIMM is installed in the socket. The above shows all of the possible memory configurations. When installing more than 16MB of memory, BIOS relocation must be disabled. Bios relocation copies the video Bios (C0000-C7FFF) and the system ROM Bios (F0000-FFFFF) into RAM. The motherboard adds 15MB to these addresses (F00000) to be able to differentiate between the ROM and RAM. Enabling the relocation feature causes the memory above 16MB to become non-contiguous and therefore inaccessible. Micronics Computers has tested and verified the following 1Mx36 memory brands: Micron Technologies, Mitsubishi, Samsung, Texas Instruments, Toshiba Micronics Computers has tested and verified the following 4Mx36 memory brands: Mitsubishi, Samsung, Toshiba +=============================+ + + + MOTHERBOARD JUMPER SETTINGS + + + +=============================+ J5 External 6-volt battery connector Pin 1 - Battery Positive Pin 2 - no connector Pin 3 - Ground Pin 4 - Ground J7 Keylock / Power LED Pin 1 - Power LED signal Pin 2 - no connector Pin 3 - Ground Pin 4 - Keyboard lock signal Pin 5 - Ground J8 External speaker Pin 1 - Speaker Pin 2 - no connector Pin 3 - Ground Pin 4 - +5 volts DC W1 Turbo LED Pin 1 - Signal Pin 2 - Ground W2 Reset switch Pin 1 - Signal Pin 2 - Ground W3 Turbo switch Pin 1 - Signal Pin 2 - Ground