Olivetti · M
Olivetti M15 Plus
1988 80C88 portable with 512 KB, a detachable keyboard, a backlit monochrome LCD and dual-floppy or 20 MB HDU configurations.
EXPERIMENTAL: the documented tests belong to the earlier pilot. This updated build still needs interactive regression testing. No add-on sound cards are supported; the internal speaker remains. Hardware approximations and unverified peripherals are described below.
History
The M15 Plus is a distinct Olivetti portable related to the base M15. It combined an 80C88 at 4.77 MHz, 512 KB, a detachable keyboard and a 10.5-inch backlit LCD. Olivetti sold either two internal 720 KB floppy drives or one floppy with a 20 MB HDU; both configurations are represented experimentally.
Hardware
- Processor
- Intel 80C88 at 4.77 MHz
- Memory
- 512 KB user RAM; 16 KB video RAM
- Video
- 10.5-inch backlit super-twist monochrome LCD; eight observed shade codes, 40/80-column text and 320×200/640×200 BIOS graphics modes
- Floppy drive
- Pilot: two internal 3.5-inch, 720 KB drives
- Clock and CMOS
- Battery-backed clock/calendar; BIOS accesses an MSM6242-compatible register set at 0100h-010Fh
- Interfaces
- RS-232C, Centronics parallel and optional external 5.25-inch floppy; no documented external video connector
- Keyboard
- Detachable 78-key keyboard with latching EDIT/SHIFT, integrated numeric keypad and ten function keys
- Hard disk
- Alternative commercial configuration: one 720 KB floppy and one 20 MB internal HDU. Olivetti labels the drive interface SCSI; the integrated host adapter is modelled through its BIOS-observed XT-compatible register contract
Catalogue classification
- Form factor
- Laptop
- Mobility
- Portable
- Processor generation
- 8086 class
- Graphics standard
- CGA-compatible
- Display technology
- LCD
- Display colour
- Monochrome
- Storage interface
- Floppy drive
Research
This page separates documented hardware facts, behavior observed in original firmware, and the current fidelity of BluMach emulation.
Architecture and memory
Evidence: documented or confirmed hardware
- CPU and bus
Intel 80C88 at 4.77 MHz with 512 KB user RAM. The available emulator core and calibrated timer remain timing approximations.
- Options and peripherals
The manual documents an optional self-powered external 5.25-inch floppy unit and peripherals on RS-232C/Centronics. Battery, supply, shoulder strap and bag are accessories, not ISA slots. Profiles offer two 720 KB drives or one drive plus the 20 MB HDU, with fixed 512 KB and internal speaker. External floppy support remains pending; no ISA sound cards are offered.
- Video
Backlit super-twist monochrome LCD. The original utility names black, six grey levels and white; the Plus renderer preserves those eight levels with an approximate luminance curve. The guide documents 40/80-column text and 320×200/640×200 graphics; a brochure's conflicting 640×320 claim is not exposed as an emulated mode. Its olive background and cool blue-grey/green active pixels reuse the approved portable M15 appearance; the colours are approximate, not panel measurements. The Plus retains its eight ordered levels with interpolated tones, without claiming the same optical response as the non-backlit M15.
- Jumper bank
BIOS 1.10 decodes the same multiplexed memory and 40/80-column startup bits as M15. Memory is fixed at the documented 512 KB; Configure exposes only the firmware-backed startup text choice.
- Analyzed firmware
Local BIOS 1.10: 32 KB mapped at F8000h-FFFFFh, reset date 06/03/88 (US format MM/DD/YY: 1988-06-03). It remains local-only pending provenance and rights verification.
Emulation status
Evidence: current BluMach status; not necessarily a description of the original circuit
- Screen controls
The guide documents contrast, speaker volume and backlight ON/OFF. View → Screen controls offers contrast and backlight live, with eight ordered LCD levels. The guide mentions no separate brightness dial, so none is added. OFF lowers the illumination but does not power the panel down. The optical curves are approximate.
- Implementation lineage
The model reuses the evidence-backed M15-family board-switch, MSM6242 RTC and V6355D paths while preserving a separate identity and 32 KB firmware map. Its dedicated HDU/SCSI device reuses the XTA host state machine for the BIOS-observed 320h-323h, IRQ 5 and DMA 3 contract, including buffer and long-sector diagnostic commands.
- Verified
Cold boot and both reset paths pass Resident Diagnostics and report 512/512 KB. Original media boots under MS-DOS 3.20; its configuration report identifies both internal 720 KB drives. The customer Memory, System Board and Display LCD tests pass, validating the character set, attributes, eight ordered shades and 320×200/640×200 graphics.
- Pending or approximate
The HDU host contract is implemented, but the unidentified physical SCSI bridge, drive firmware and stored ECC bytes are approximated; raw disk images synthesize the four diagnostic ECC bytes. Exact LCD response, timer calibration and remaining custom board logic also remain approximate.
Engineering
This public engineering narrative explains how the evidence became an emulator implementation, including failures, compromises, validation and replacement criteria.
Sources
Sources and traceability
Evidence: primary sources and research notes
- Original product brochure
- Olivetti M15 Plus brochure 01200090 G (March 1988)
- Analyzed firmware
- M15 Plus BIOS 1.10 index and ROM metadata (Minus Zero Degrees)