Olivetti · M
Olivetti M300 (IF378)
Modular 16 MHz 386SX M300 with an IF378 CPU card and Intel 82335 memory control.
History
The original modular M300 combines the IF378 CPU card, IN108 bus and GO477 multifunction board. It is not the same motherboard as later numbered M300 desktops.
Hardware
- Processor
- Intel 80386SX 16 MHz on IF378
- Memory
- 1–12 MB
- Chipset
- Intel 82230/82231/82335
- Expansion slots
- IN108 system bus; GO477 multifunction board
Catalogue classification
- Form factor
- Desktop
- Mobility
- Stationary
- Processor generation
- 80386SX class
- Storage interface
- Floppy drive, IDE
Research
This page separates documented hardware facts, behavior observed in original firmware, and the current fidelity of BluMach emulation.
Sales and commercial configurations
Evidence: documented or confirmed hardware
- Commercial models
The original M300 is modular: the CPU board (UC093/097 and later UC112/113, with the IF378) plugs into slot 3 of the IN108 bus board, which has 8 slots (five 16-bit and three 8-bit). The GO477 multifunction board and the GO481 VGA take two more.
Architecture and memory
Evidence: documented or confirmed hardware
- CPU and bus
16 MHz Intel 386SX with an 80387SX socket. The Intel 82230/82231 hold the AT logic (clock, interrupts, DMA, timer, RTC) and the 82335 controls memory.
- Memory
Up to 12 MB: two banks on the CPU board (1 MB with 256 KB SIMMs, or 2 or 4 MB with 1 M × 9 SIMMs) and AMB 2678 memory boards of 2 to 4 MB. 100 ns access.
- Video
GO481 VGA board in bus slot 6. It is not emulated; the profile uses an external Paradise PVGA1A.
- Storage
The GO477 combines the disk interface, the floppy controller (WD37C65C) and the serial port. Documented disks are 20, 40 and 100 MB (Conner, NEC, Quantum). The BIOS table includes type 33 (776/8/33) and type 36 (805/4/26).
BIOS and firmware
Evidence: observed in preserved firmware and boot testing
- Known revisions
BIOS 1.09 (06/26/90), 64 KB in a 27C512, is preserved. The service guide places 1.09 on the UC112/113 boards and lists a later 1.10 that fixes the loss of the first key after Ctrl+Alt+Del with shadow memory disabled.
Emulation status
Evidence: current BluMach status; not necessarily a description of the original circuit
- Verified
With 2 MB, Resident Diagnostics complete their tests and count 640 KB base, 1280 KB extended and 128 KB shadow (2048 KB) after the BIOS memory remapping sequence; the ROM Setup then opens. MS-DOS 3.30a had previously been observed booting with saved NVR state.
- Pending or approximate
Bootable partial emulation. The 82335 memory configuration, memory remapping and the on-board memory ranges the BIOS uses to size memory are emulated. Memory does not repeat beyond the installed amount as on the real board, and the remapped memory sits directly above installed memory. The 82230/82231 and GO477 functions are composed from compatible AT devices, and the GO481 still requires an external VGA. The IDE disk, other memory sizes and more software remain to be validated.
Sources
Preserved research material
Evidence: primary sources and research notes