The Professional 325 (PRO-325) and Professional 350 (PRO-350) were PDP-11 compatible microcomputers introduced in 1982 by Digital Equipment Corporation (DEC) as high-end competitors to the IBM PC. Like the cosmetically similar Rainbow-100 and DECmate-II (also introduced at that time), they used the LK201 keyboard and used 400kB single-sided quad-density floppy disk drives (known as RX50 and offered a choice of colour or monochrome monitors.

For DEC, none of the three would be favourably received and the industry instead standardized on Intel 8088-based IBM PC compatibles which were all binary program compatible with each other. In some ways, the PDP-11 microprocessors were technically superior to the Intel-based chips. While the 8088 was restricted to 1MB of memory because of its 20-bit address bus, DEC microprocessors were capable of accessing 4MB with their 22-bit addressing (although direct addressing of memory was limited in both approaches to 64KB segments, limiting the size of individual code and data objects). But other factors would weigh more heavily in the competition, including Digital's corporate culture and business model, which were ill suited to the rapidly developing consumer market for computers.

The PRO-325 and -350 used the F-11 chipset (as used in LSI-11/23 systems) to create a relatively compact single-board PDP-11 with up to 6 expansion slots of proprietary CTI (Computing Terminal Interconnect) bus using 90- pin ZIF connectors. The PRO family used RX50 floppies for storage; the PRO-325 had only floppies, the 350 and 380 also included an internal hard drive. Mainline PDP11s generally used separate serial terminals as console and display devices; the PRO family used in-built bit-mapped graphics to drive their combined console and display. All other I/O devices in the PRO family were also different (in most cases, radically different) from their counterparts on other PDP-11 models. For example, while the internal bus supported direct memory access (DMA), none of the available I/O devices used this feature.

Our machine has a model number of PC350-D.

Manufacturer: Digital
Date: 1982

This exhibit has a reference ID of CH30305. Please quote this reference ID in any communication with the Centre for Computing History.

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