danny@garnet.berkeley.edu (Danny Lee) (10/18/90)
Hi there! I've just acquired a true blue IBM-AT with a board in it that has no documentation. It *seems* to be able to handle 3 megs of memory using SIMMS and has 1 parallel and 1 serial port. Does anyone have any info on this beast? If so, could someone please email me the switch settings for the different memory configurations? Presently its got 1.5 megs of SIMMS on the board. System configuration: 512K System memory 1 - 1.2 and 360K 5.25" drive CGA card and moniter 1 SEAGATE ST4096 (80 meg drive partitioned w/Speedstor) using a standard IBM floppy/hard drive controller. Enhanced keyboard Thanks in advance. Danny Lee danny@garnet.berkeley.edu (415) 486-1768
medici@dorm.rutgers.edu (Mark Medici) (10/19/90)
danny@garnet.berkeley.edu (Danny Lee) writes: |Hi there! | I've just acquired a true blue IBM-AT with a board in it that |has no documentation. It *seems* to be able to handle 3 megs of memory |using SIMMS and has 1 parallel and 1 serial port. Does anyone have |any info on this beast? If so, could someone please email me the switch |settings for the different memory configurations? Presently its got |1.5 megs of SIMMS on the board. 1. A "true-blue" IBM PC/AT motherboard only accomodates a maximum of 512kB RAM on the motherboard. It does NOT support SIMMS on the motherboard. Depending on the motherboard revision, either 64kB DIPS, 128kb DIP modules, or 256kB DIPs can be installed. There is a jumper located on the front right corner of an IBM PC/AT mother- board to specify whether 256kB or 512kB of RAM is installed on the motherboard. This jumper changes the way the RAM on the motherboard is addressed. Other than changing the motherboard RAM addressing mode (via the above mentioned jumper), all other memory settings are maintained in battery-backed CMOS RAM. The IBM Personal Computer AT Diagnos- tics and Setup Diskette allows you to change these settings. 2. An IBM PC/AT motherboard does not have any serial or parallel ports built in to the motherboard. These are supplied on an expansion adapter available standard on the IBM 5170-339 (8MHz system with 30MB fixed drive), and optional for all other models. 3. A "true-blue" IBM PC/AT motherboard has but a single switch - the one that is used to select the primary display adapter. Setting this switch ON (toward the front of the system unit) selects a Color Graphics or compatible adapter as the primary display adapter, while OFF selects a Monochrome Display and Printer Adapter as the primary adapter. The primary adapter is the one that will, by default, be active when the system is powered-on or rebooted. If there is only one display adapter installed, this switch should be set to reflect the capabilities of that adapter. -- ---------------------------------------------------------------------------- Mark Medici/SysProg3 * Rutgers University/CCIS * medici@elbereth.rutgers.edu ----------------------------------------------------------------------------