Olivetti · Prodest
Olivetti Prodest PC 1 HD
Distinct 640 KB Prodest model with NEC V40, integrated V6355 video and a factory 20 MB hard disk.
PARTIAL EMULATION: BIOS 1.21, 640 KB, video, floppy and the factory 20 MB XTA disk work; FDISK, FORMAT /S and booting from the hard disk have been checked. The exact geometry of the 40 MB selector and the native V40 peripherals remain unresolved.
History
The PC 1 HD was sold as a separate member of the Prodest PC 1 family rather than merely as a user-selected disk option. Period Italian advertising documents the 20 MB configuration; surviving board photographs show BIOS 1.21 and a dedicated internal 40-pin disk connection.
Hardware
- Processor
- NEC V40, switchable 4.77/8 MHz
- Memory
- 640 KB visible; 768 KB physically populated according to the technical guide
- Video
- Integrated Yamaha V6355-compatible display logic with 16 KB mirrored VRAM
- Floppy drive
- One internal 3.5-inch 720 KB drive
- Hard disk
- Internal 8-bit XTA interface at 0320h-0323h, IRQ 5; 20 MB factory configuration
- Interfaces
- Serial, parallel, audio, RGB/mono and quadrature mouse/joystick
Catalogue classification
- Form factor
- Desktop
- Mobility
- Stationary
- Processor generation
- 8086 class
- Storage interface
- Floppy drive, XTA
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
NEC V40 with 8-bit external bus and BIOS-controlled 4.77/8 MHz operation; the current model uses the dedicated BluMach V40 register device over its V20 instruction core.
- Memory
640 KB are visible to software. A technical guide documents 768 KB physically populated on the PC1HD board; the additional 128 KB are not mapped as conventional memory.
- Video
Integrated Yamaha V6355D with 16 KB physical VRAM mirrored at B0000h, B4000h, B8000h and BC000h. BluMach reproduces the aliases and their BIOS-controlled visibility.
- Storage
One internal 720 KB floppy and an onboard 8-bit XTA controller at 0320h-0323h, IRQ 5, without an option ROM. The initial profile uses the BIOS 1.21 table geometry 667 cylinders, 2 heads and 32 sectors (20.84 MiB).
BIOS and firmware
Evidence: documented or confirmed hardware
- Known revisions
Dedicated 16 KB system BIOS 1.21, SHA-256 A2C03DC2E8752EA1632B910B4CE46AF7AB5FC6D4B352D8E21703B2ABB5791F96. ROM bytes are not distributed with BluMach.
Emulation status
Evidence: current BluMach status; not necessarily a description of the original circuit
- Verified
BluMach passes Resident Diagnostics 1.21 for CPU, ROM, DMA, interrupts, timer and 640 KB RAM. With Spanish MS-DOS 3.20, FDISK creates the partition, FORMAT /S completes and the machine boots autonomously from the 20 MB disk. BIOS normal/4.77 MHz selection works and survives Ctrl+Alt+Del.
- Pending or approximate
The XTA command engine is shared and the V40 DMAU path is an explicit translation layer, not a native integrated DMA implementation. Cold reset, PC1HD turbo-state preservation, sustained disk I/O, broader software and the documented 40 MB alternative still require validation.
Sources
Preserved research material
Evidence: primary sources and research notes