Olivetti · M
Olivetti M300-30
25 MHz i486SX desktop with VLSI VL82C486 chipset and integrated WD90C31 video.
History
The M300-30 is the 25 MHz i486SX version of this 1992–1993 M300 platform. It shares its board, firmware and peripherals with the M300-30P, which has a DX2/50; BluMach offers them as two machines so that each has its own processor.
Hardware
- Processor
- Intel i486SX/25
- Memory
- 4/8/12/20/24/36 MB
- Chipset
- VLSI VL82C486
- Video
- Integrated Western Digital WD90C31, 1 MB
- Input and output
- PC87311/87312 family; separate Olivetti 8042
Catalogue classification
- Form factor
- Desktop
- Mobility
- Stationary
- Processor generation
- i486 class
- Graphics standard
- VGA
Research
This page separates documented hardware facts, behavior observed in original firmware, and the current fidelity of BluMach emulation.
Architecture and memory
Evidence: documentation, reverse engineering and diagnostics
- CPU and bus
25 MHz Intel i486SX. VLSI VL82C486 chipset, combining the memory and AT-bus controller.
- Memory
4 to 36 MB (4, 8, 12, 20, 24 or 36 MB). With 4 MB, POST counts 640 KB base, 3072 KB extended and 384 KB dedicated: the 384 KB behind the hole between 640 KB and 1 MB are reserved for video and BIOS shadowing.
- Video
Integrated Western Digital WD90C31 VGA with 1 MB. Its video BIOS, OVC 1.09, takes the lower half of the ROM.
- Storage
PC87311/87312-family Super I/O (floppy, serial and parallel) and a buffered IDE interface. The BIOS table adds types 17 to 26 for IDE disks, including type 17 (805/4/26, 40 MB) and type 18 (776/8/33, 100 MB).
BIOS and firmware
Evidence: observed in preserved firmware and boot testing
- Known revisions
Three 128 KB ROMs with the same OVC 1.09 video BIOS are preserved: Diagnostics 1.03 (09/24/92), 1.04 (11/05/92) and 2.00 (02/22/93). The BIOS reads the bus speed (25 or 33 MHz) and the Super I/O address from a board register, which it opens with keyboard-controller command 8Bh.
Emulation status
Evidence: current BluMach status; not necessarily a description of the original circuit
- Verified
Diagnostics 1.04 has completed POST, CPU, cache, memory, keyboard, RTC and protected-mode tests, booted MS-DOS 5.00 and retained the calendar. At 4 MB, memory is accounted as 640 KB base + 3072 KB extended + 384 KB dedicated = 4096 KB.
- Pending or approximate
Partial bootable emulation. The VL82C486 is an initial model; the WD90C31 uses the compatible WD90C30 core and the PC87311/87312 is approximated with PC873xx. The board configuration register, from which the BIOS reads the bus speed and the Super I/O address, has been reconstructed from the disassembly. The other documented RAM configurations and more software remain to be validated.
Sources
Sources and traceability
Evidence: primary sources and research notes