This document is for the baby-sized (13.3" x 8.5") Gemini VL-Bus motherboard. The part number for this board is 09-00144-xx. It's identifying features are: an LED between expansion slots #5 and #6; six 16-bit expansion slots; two 16-bit/VL-Bus expansion slots; four sockets for SIMMs; a socket for an OverDrive CPU; two IDE interface connectors; one floppy connector; two serial port connectors; one parallel port connector. The ISA bus speed for this motherboard is fixed at 8MHz. The VL-Bus bus speed is determined by the CPU speed. If the CPU is a 486SX-25, or 486DX2-50, the VL-Bus bus speed is 25MHz. If the CPU is a 486SX-33, 486DX-33, or 486DX2-66, the VL-Bus bus speed is 33MHz. +=============================+ + + + 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 CPU selection (see below) 6 CPU selection (see below) 7 CPU selection (see below) 8 CPU selection (see below) DIP switch settings for memory size =================================== Memory Banks DIP Switch 1 ----------------------------------------------- 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 DIP switch settings for CPU selection ===================================== DIP Switch 1 --------------------- CPU Speed S5 S6 S7 S8 -------------------------------------- 33MHz or 66MHz Off On Off Off 25MHz or 50MHz On Off On Off +=============================+ + + + MOTHERBOARD JUMPER SETTINGS + + + +=============================+ J11 Com Port A J12 Parallel Port J14 Com Port B J15 Floppy connector J16 Primary IDE connector J24 External 6-volt battery connector Pin 1 - Battery Positive Pin 2 - no connector Pin 3 - Ground Pin 4 - Ground J28 External speaker Pin 1 - Speaker Pin 2 - no connector Pin 3 - Ground Pin 4 - +5 volts DC J29 Keylock / Power LED Pin 1 - Power LED signal Pin 2 - no connector Pin 3 - Ground Pin 4 - Keyboard lock signal Pin 5 - Ground J30 Secondary IDE connector W13 CPU selection Pins 1-2 486DX, 486DX2 Pins 2-3 486SX W15 Reset switch Pin 1 - Signal Pin 2 - Ground W16 Parallel port I/O direction Pins 1-2 Input mode Pins 2-3 Output mode (default) W17 Turbo LED Pin 1 - Signal Pin 2 - Ground W18 Turbo switch Pin 1 - Signal Pin 2 - Ground W19 IDE LED Pin 1 - Signal Pin 2 - Ground W20 Flash ROM operation (see note below) Pins 1-2 Recovery Pins 2-3 Normal operation (default) DO NOT change jumper W20 unless instructed by a Micronics Technical Support Engineer. Changing the jumper will result in the Bios being erased. You must have a Flash recovery floppy diskette before attempting to recover. The jumper is NOT moved when updating the Flash ROM. +==========================+ + + + Additional Information + + + +==========================+ I/O Port addresses ------------------ COM1 3F8h COM2 2F8h COM3 3E8h COM4 2E8h LPT1 3BCh LPT2 378h LPT3 278h IRQ list -------- IRQ 6 Floppy controller IRQ 14 Primary IDE controller IRQ 15 Secondary IDE controller When using the on-board I/O ports, the interrupts used cannot be shared with another device. IRQ14 and IRQ15 cannot be shared, regardless of whether or not IDE drives are attached to the on-board connectors.