RML 480Z Shared-Disc System Brochure

Research Machines's brochures tended to be undated, but it is likely this was produced in 1984. The thumbnails link to 75dpi scans of the pages (622 KiB for all four); higher quality images are available on request.


RML 480Z Shared-Disc System: Economical. Simple. Reliable. Upgradeable.

As computer programs become more sophisticated, users find themselves looking for more and more data storage space. Like any good micro, the RML 480Z is designed to take a high-density, double-drive disc unit; but it must be said that disc drives cost money. And in any environment where several microcomputers may be in use at once, it can become prohibitively expensive to support each one with its own disc drive.

Now, RML have solved this problem by ingeniously adapting their 480Z micro so it can share a common disc drive with other 480Zs. And the firmware that makes this possible is already designed into the 480Z, so that the only equipment you need to build your Shared-Disc System is a disc drive unit, some cable and connectors to link everything together.

The Shared-Disc System: How It Works

The Shared-Disc System comes in the simple form of a special CP/M software disc, a cable and some connectors. The disc drive itself is connected in the normal way to a 480Z, which becomes the 'Host' micro.

The other 480Zs in the system (the 'Guest' micros) are all linked by the cable to the Host, and the CP/M software enables each Guest to use the Host's drive unit as if it were its own.

What are the Economies?

HARDWARE. The Shared-Disc System allows the cost of one disc drive to be shared between several micros. So the benefits of disc storage can be extended to several users without buying more disc drives.

Many so-called 'networks' require one micro full time to run the discs, thus losing it as a user station. The 480Z Shared-Disc System allows every station to be used, without significantly encroaching on its memory capacity.

The economies are significant. Four RML micros in a Shared-Disc configuration give a real overall saving of 40% over four separate micros, each with its own disc drive.

SOFTWARE. On sites with more than one microcomputer, much of the software is often duplicated for each micro: systems information, languages, programs and applications. With the Shared-Disc System, you can share the programmes you have developed, without having to copy them for each computer. And of course, data files can be shared in the same way.

This makes Shared-Disc an ideal configuration for classrooms, at every level of education. It allows an entire class to work interactively, even on high level learning programs which need disc storage to run them.

Fast, Simultaneous Access

For reading, any disc may be accessed at any time by any station. For writing, a disc side is either allocated to one station, or it can remain free to be claimed by any station. Thus, on a four station Shared-Disc System with twin drives, each 480Z can simultaneously access the system. Compare this with other low-cost networks, where the user has to wait until the disc drive is free.

How Does the Shared-Disc System Compare With Other Networks?

The Shared-Disc System can be viewed as a stepping stone to a full Local Area Network. Without possessing all the features of the RML CHAIN Network, it is certainly more powerful and more economical than many multi-user systems for other micros which are described as 'networks'. The standard 480Z will drive the system without any extra processors or additional ROM chips. The system is simplicity itself to wire up: no soldered joints, clock boxes, complex wiring runs or extra power supplies to go wrong. Just a single coaxial cable running to a socket at the back of each station.

In the short term the 480Z Shared-Disc System is a shrewd and economic way to start networking. In the long run, it provides a low-cost upgrade route to a full RML CHAIN Network. And it is covered by RML's free Technical Support service, to give you help and advice whenever you need it.

Upgrade Paths

The Shared-Disc System enhances the already unique upgrade path which allows the 480Z system to grow with the user's evolving needs and budget. The low cost entry level cassette version can run with cassette or RML's fast, sturdy ROM Packs. For the more demanding user, the 480Z disc drives provide powerful and efficient storage back-up.

The Shared-Disc System allows multi-user facilities at very low cost, whilst complete interactive networking for up to 16 users is possible with the RML CHAIN Network.

RML 480Z Shared-Disc System Specifications

The Shared-Disc runs with 480Z Disc Drive Units made and supplied by RML for running with the LINK 480Z computer. This is a robust disc unit complete with its own Intelligent Disc Controller, power supply and internal fan.
A working Shared-Disc configuration needs:
Computers –2 or more 480Zs with:
   Memory 64K RAM
Resident Operating System ROS 1.2B or later
Network Interface Hardware Transceiver
Network Interface Firmware ZNET 1.1Q or later
Drive unit Single or twin drives
Disc CP/M with Shared-Disc support
Connectors 1 T-piece per station
Cable According to distances required
Terminators 2
480Z DISC DRIVE UNIT: Technical Details
Drives Single or twin
Disc size 5.25 inch
Density Double and single density (with automatic density switching)
Encoding MFM/FM
Capacity 656K bytes twin drive double density (formatted)
328K bytes single drive double density (formatted)
164K bytes per side double density (formatted)
Tracks 40 tracks per side at 48 tracks per inch
Sectors 16 x 128 byte sectors (single density)
9 x 512 byte sectors (double density)
Speed 300 rpm
Interfaces a) 480Z communicates with the Disc Drive unit IDC via a 125K baud Async link from the SIO-4 port
b) 480Z SIO-4 is extended and sits on the IDC offering SIO-4 facilities with bi-directional Async data transfer at preferred baud rates from 110 to 9.6k baud
Fan 50mm diameter
Power 32 watts maximum
On board fused power supply
Power Supply 220-240 V AC 50Hz
Dimensions 195mm x 310mm x 190mm
Weight 7.7 kg (twin drive)
Load rates 3.5K bytes/second