A powerful multi-user system for under £6,600

As more adverts are added to the collection, the challenge is on to discover more and more obscure microcomputers that time forgot.

And this is defintely one such computer: the Clenlo Ace Multi-User System, from Clenlo Computing Systems of south-east London, a company that disappeared without trace but which was at one point a reseller of Morrow Design's [=morrow_praccomp_1982-10|Decision 1].

The company had however been around since at least the October of 1980, when it was offering a single-user Z80/S-100 system called the Clenlo Conqueror. 

By early 1981 it was offering a version of the Conqueror with the optional extra of an "attractive desk unit" to house the computer. It was pitched as a word-processing system and retailed, complete with a daisy-wheel printer, for £4,600[source: PRAC, March 1981, p. 25] - about [[4600|1981]] in [[now]]. 

There was also a System B version available for £1,950 and a hard-disk-only System D for a hefty £5,150, or [[5150|1981]] now.

[picture: Clenlo_conqueror_prac_mar81.webp|An advert for Clenlo Computing Systems from PRAC's March 1981 edition showing the company as a general value-added reseller, selling software and Morrow disc-storage units, but also the Clenlo Conqueror - a Z80 machine with a twelve-slot S-100 motherboard]

Clenlo's Conqueror was popular enough to have been one of the machines supported by Prospero Software's ProPascal[source: https://www.moorecad.com/standardpascal/pug_newsletter_23a.pdf], where it was in illustrious company including the [#Comart Communicator], [#Nascom 3], North Star [#Horizon], RML [#380Z] and even the [#Apple II].

It was even possibly the system that Pro Pascal was developed on, or at the very least Prospero Software had one in their office for testing[source: "Pascal Update", PCW, May 1982, p. 139].

The Ace, meanwhile, was a multi-user system in the style at the time, which was to host an individual processor and memory board for each user - which Clenlo called the DPC-180 and which was based on a Z80A - on an S-100 bus, with another Z80A CPU to manage everything. 

[picture: Clenlo_s100_prac_feb82.webp|The illustration from the advert which nicely shows the multi-user architecture in use at the time: multiple plug-in boards, each with their own CPU and memory, on an S-100 bus]

Each user then shared systems resources like printers and hard disk, whilst connecting to "their" processor, which ran CP/M, over RS232 serial with a terminal of some sort, whilst the system itself ran DPC/OS multi-user operating system.

That terminal could even be a Commodore [#PET], which despite being a fully-functional micro in its own right was actually cheaper than many dedicated mainframe terminals[source: "Commodore as terminal", PRAC, February 1982, p. 47].

Hard disk storage, which could be up to 100MB, was managed via a disk controller from [@Morrow Designs], founded by George Morrow.

A basic two-user system retailed for £6,580 plus VAT, which is about [[7600|1982]] in [[now]].

That works out at a hefty [[3800|1982]] per user for the initial system, although that was actually about the same as a reasonably-specified IBM PC, when that was finally released in the UK in 1983.

The point of multi-user systems like this though was that incremental prices for the next fourteen users were significantly less, although sadly the advert doesn't say how much the DPC-180 cards cost.