Review of the Microdigital Mico


On my eighteenth birthday my parents gave me the offer of paying for a computer for my university course. With the recent demise of Acorn, I had three options; either upgrade my Risc PC, buy a top-of-the-range Windows PC, or wait for one of the new RISC OS machines reputedly in development. Having investigated the price of upgrading my computer (a 600 series with a tiny 200Mb hard disc), I worked out that the total cost of upgrading to the best modern specification would be around 800ukp; enough to buy a new computer in other words.

Having discarded the upgrade option in the face of the exorbitant price of Acorn parts (a subject I will not tackle here), I was left with a choice between the very attractive PC route and the rather rocky RISC OS route. After much painful deliberation, I decided to stick with RISC OS and see what happened to the platform.

Initially I was sold on the RiscStation computer, with the promise of the PCI bus for graphics and sound cards. Sadly, however, after months of telephone enquiries, I discovered that they were abandoning the PCI bus, at least for the present. Suddenly it was a two horse race again, with the expansion possibilities of the Microdigital Mico an attractive proposition.

Before beginning this review I should probably mention that I am quite a demanding person in terms of computer hardware. An ARM2 computer would be perfectly adequate for the use of a primary school to run Dazzle or Impression, but I am one of the queer group of people who try (amongst other travesties) to play games on Acorn computers, despite that company's manifest disinterest in the games market over the years.

First impressions

First impressions of the Mico were good. Arriving on my doorstep right on time (although several months after I posted my cheque!) was a large square box, very professionally packed and labelled. Unpacking this revealed three packages; one containing leads, a mouse and a manual, another containing a very sturdy keyboard, and the third an ATX tower case. I decided to do everything by the book, setting the computer up strictly according to the diagrams in the manual, although these assume a desktop case.

The tower case is huge; there is no other way to describe it, if you are used to single slice Risc PCs. It is fairly square and functional, except for a wider skirt at the base. The drive bays are recessed, and the floppy drive hidden behind the facia. The blue oval reset and power buttons are in line above the drive/power lights to the right of the front.

The manual supplied, entitled 'Mico Computer - Getting Started' is adequate, full of black and white photographs. In the main it is aimed at the user unfamiliar with RISC OS, so I had no real use for it. Unfortunately, like Microdigital's publicity literature it reads "as though written by someone for whom English is not their first language" (the words of my sister). Correctly spelt, but grammatically strange. There is one section entitled 'Help its doesn't go', which didn't exactly instil confidence in me.

On switching on for the first time, I was struck by how much more quickly the machine booted up than my Risc PC, which can take more than 1½ minutes. In no time at all, the RISC OS 4 title disappeared, and we reached the desktop. In use, the computer is refreshingly quiet, and it was nice not to be subjected to a continuous, irritating whine from the hard disc (like my Risc PC.) The exception to the near silent running is the CD-ROM drive; the door comes out with a loud whir-clunk, and when spinning up to speed it makes a noise like a jet taking off. Mind you, I think that all fast CD drives do this.

I was rather worried by the absence of any instructions in the manual on either the 10baseT network card which I had purchased with the computer, or the sound card. I was completely unable to get any sound out of the computer. I couldn't see an internal speaker, so I went round like a doctor, listening through headphones to all the sockets, but to no avail. As usual, the 'trouble shooting' ideas in the manual were not of use to anyone but a novice.

I phoned up Microdigital to enquire about the lack of sound, and was told that because of supply problems with the original sound chip set, they were now using an ISA sound card instead of having sound on the motherboard. Because of the switch, software drivers for the PC hardware were not yet available, and would be posted to me when finished.

The Hardware

I will not spend too much time describing the specification of the machine, since this has been widely publicised. In any case, I was more interested in actual performance. The machine is based around the 56MHz ARM7500FE processor with integrated floating point arithmetic unit, video and memory controllers. A fast EIDE interface supports up to 4 drives. The standard system is provided with 16Mb EDO RAM and a 6.4Gb hard disc, but I bought a custom built system with 64Mb RAM/8.4Gb HD. A 48xCD-ROM drive is optional.

Keyboard and mouse are PS/2 standard. The keyboard is very sturdy in contrast to the rather tacky Risc PC keyboard. The keys are of the 'squishy' rather than the 'clicky' variety; not my taste I'm afraid. The mouse is the same Logitech mouse as the Risc PC mouse, but with much nicer microswitches.

Sound is 16-bit with hardware wavetable synthesis, audio in/out/mic sockets and a MIDI in/out port which doubles as a gameport. In terms of expansion buses, ISA cards (PC) are supported (if drivers are written), 4 USB ports exist for peripherals, and internally a 'MicroBus' supports Acorn podules (with adapter) or fast proprietary expansion cards.

The computer is supplied in an ATX case (the type capable of switching itself off), either Desktop or Tower (no extra charge). The tower case features three 5¼" drive bays rather than the single one in the desktop case.

The Software

The Mico is supplied with RISC OS 4.03 in Flash ROMs, with a MicrodigitalUtl module, presumably to provide support for the new hardware. It is not really appropriate to examine OS 4 in detail here: Briefly, it is similar to OS 3 but with nicer configuration, aesthetic improvements, a new 'iconise' button and long file names. The new icons are a love/hate issue with many people; I like them. Three improvements in areas that used to drive me mad are the ability to set the 'Work directory' (CSD) from the desktop Filer, to iconise windows to the iconbar, and to avoid fiddling inside your !Boot structure.

As expected there were software casualties with the new operating system, though not many. So far, I have lost High Risc Racing and Drifter. Star Fighter 3000 worked after the positively evil disc protection had been hacked out. A 3D demo didn't work, suffering flickering on the screen refresh.

APDL's IDEFS is used for the hard disc, rather than ADFS. This can cause problems for ancient, badly written software, but it is not generally significant. Also, IDEFS has some advantages over ADFS, such as different levels of password protection on discs, and an optional powersaving (spindown) delay.

My computer was supplied with the hard disc divided into two partitions. One of these, 'Apps' contained the software supplied with the computer; the standard RISC OS applications CloseUp, SciCalc, Maestro, Printers, CDPlayer, ChangeFSI and Squash, the Diversions directory as supplied with Risc PCs and a directory containing IDEFS utilities. Replay was notably absent, as was PhotoView, despite this being described in the manual! I was also perturbed by the absence of Fireworkz Professional, Pipedream and the RISC OS 4 collection, which were advertised as being supplied with the computer!

Another phone call to Microdigital, and I was assured that this was not their fault; various third parties had reneged on previous software agreements. The manual had been written assuming the original software bundle. I got the impression that in future, Micos would optionally be sold at an increased price, bundled with Fireworkz and Pipedream, but this time with manuals.


To start with, I would like to squash two false rumours surrounding the Mico: As with other computers being shipped with the 56MHz ARM7500FE processor, Microdigital's advertising literature claims a speed of '50 MIPS' (fifty million instructions per second). To put it politely, this is completely untrue. I found that on both the R7500Lite and the Mico, ARMsi (a RISC OS speed indexer) returned a speed of 33MIPS. My second point of contention is that the otherwise authoritative article in Acorn User claimed the Mico to be "2.5-4 times faster than a Risc PC 700". From my extensive testing, the truth is nearer 1-2 times faster than a Risc PC 600, and for some applications, the Mico was actually found to be slower!

Since I am highly sceptical of manufacturer's claims (from past experience), I decided to do some 'real world' tests on the Mico. The table shows the comparisons I made between my ARM610 Risc PC (1Mb VRAM) and the Mico. I will not bother explaining the details of all the trials I ran, but suffice to say that I spent a day in careful timing, with many tests repeated and averaged for accuracy.

Benchmark Mico Risc PC 600 Improvement
CPU speed 33.06 MIPS 18.05 MIPS 83% faster
RAM speed 31ns 62 ns 100% faster
Dhrystones per second (/with video DMA) 79575 / 47847 37360 dhr/s 112% / 28%
Floating Point 420309 FLOPS 49408 FLOPS 751% faster
FQuake average fps 2.9 fps 1.7 fps 71% faster
Copying 32Mb file 13.36 seconds 65.85 seconds 393% faster
1.55Mb file from disc 31.06 seconds 39.93 seconds 28% faster
Global replace on 501*692 4bpp image 27 seconds 24seconds 11% slower
Finding word in novel 17 seconds 28seconds 65% faster
Traversing SF3000 map (unlimited speed) 22 seconds 38seconds 73% faster
ChangeFSI 1024x768 to 8bpp sprite 12.56 seconds 18.77 seconds 49% faster
Doom torture test (480x352, max gfx) 2.05 fps 1.2666 fps 62% faster
Finding 1 file in 486 18 seconds 19 seconds 5% faster

The most impressive improvement by far was in the Mico's handling of file operations, probably due to the exceptionally fast EIDE interface. The hard disc data transfer rate of 2.40Mb/s put the Risc PC's 0.49Mb/s in perspective, the CD-ROM drive delivered an equally scorching 1.77Mb/s, and even floppy disc reading was improved by 28%. File transfer operations were done intensively, single-tasking, rather than as multi-tasking filer operations in the desktop.

The hardware benchmarks were run on ARMsi, after I had hacked it for RISC OS 4 tolerance and to recognise the ARM7500FE's floating point unit. I shouted with glee when I saw the inability of the ARMsi bar graph display to cope with the speed of the hardware FPU, which leaves a StrongARM with FP Emulator trailing in the FLOPS stakes.

I should reassure people that the frame rates quoted for Doom are not representative of the speed of these machines running Doom; I deliberately selected completely unreasonable detail levels to allow me to count the frame rate!! On the Mico, Doom (at normal resolution) is very fluid indeed (comparable to a 66MHz 486), except on very complex levels, where minor slowdown is noticeable.

I was surprised to find that the global replace operation using Paint was actually slower on the Mico, and I was also puzzled by the fact that a machine clocked twice as fast as my Risc PC was still not fluid in desktop use. Re-running the ARMsi tests with Video DMA turned on revealed the answer; in my preferred desktop mode of 256 colour 1024x768, only 50% of data bus bandwidth was available to the processor, and the Dhrystone rating had plummeted to 47847 dhr/s; little more than the Risc PC rating! Such is the price of the absence of VRAM and a dedicated video controller.

In summary, I found the Mico to be on average 69% faster for games, 33% faster for general applications, and 142% faster for file operations.


You could read this as rather a negative review of Microdigital's new machine, and my intention is that you should form your own opinions. It is true that I was disappointed with Mico, but retrospectively, my expectations were rather high. The performance was not as good as I had hoped, but despite this three factors endeared Mico to me; RISC OS 4, the ISA expansion bus, and the large, fast hard disc.

I cannot honestly recommend that people who want speedy computing should buy a Mico rather than a StrongARM Risc PC; in terms of raw power there is really no comparison. In terms of feature count, however, the Microdigital computer is the better option. Mico is a strange paradox where the integrated processor which made the design of a new computer feasible is also its biggest downfall. The fault for this does not really lie with Microdigital, since they designed their best machine with the parts currently available.

I freely admit that Mico is more expensive than the R7500Lite (and no faster), but for your money you get a machine which is much more expandable. A range of industry standard (and not!) expansion buses are provided, instead of the single-board design of the RiscStation. Obviously, Microdigital need to sort out sound drivers and their software bundle; I'm assuming these are teething troubles.

Looking ahead, with the arrival of the R7500 and Mico, software will finally start to be tailored for FPUs, to make up for the low processor speeds. The result of this may well be ARM7500FE users gloating at StrongARM users in some application areas!

In my opinion the Mico would be suited to any home office/school situation where a RISC OS 4 solution is wanted and speed is unnecessary. Castle will certainly have a fight on their hands justifying the continued sale of the A7000+, and I would strongly advise people to consider the Mico and R7500 before buying one.

For graphics/design work, the Mico would be completely unsuitable; in 16 million colours my machine was slowed to a crawl. Even 32,000 colours incurred a performance crash of 77%; to the equivalent of around 10 MIPS! Unless a radical solution with an ISA graphics card is possible, the Imago board is the only sensible option.

The Mico should not be dismissed out of hand by games players however; Doom is fluid-moving, Descent quite playable, and Quake may even be bearable, when FP tweaked. Also, older games such as Dune II and Flashback thrive on a Mico, without any StrongARM compatibility problems. The MIDI synthesiser on the sound card will be ideal for games such as Doom and Syndicate, where MIDI music is used, and the game port will save you 40ukp for a joystick interface from Stuart Tyrrell Developments.

The surprise target market for this machine then seems to be those interested in music and sound, and cash-strapped games players! Sadly, Mico is not the computer to straddle the performance gulf between those with and those without StrongARMs, as I had hoped. Despite its unparalleled versatility and expandability, Mico is neither as cheap as the Riscstation machines, nor as powerful as the StrongARM Risc PCs.

Valid HTML 4.0!