US Doubler

Reviewed by R A Matulko



Issue 15

May/Jun 85

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Double Density on the Atari 1050

Are you considering purchasing a disk drive for your Atari? Do you want more disk capacity than is available on the normal single density format? Are the double density drives from Trak or Astra unavailable or the Indus drive too expensive?

Like many others I have come to realise the inadequacy of the storage capacity and speed of the single density drive especially when using a compiler disk and when compared with the Apple or BBC drives for example. However I am accustomed to using DOS 2 on my 810 drive and did not particularly want to change to a completely different system or format I was thus very attracted to OSS's DOS XL which claimed compatibility and could also be used in double density format if I were ever to purchase a double density drive.

When Atari reduced the price of the 1050 drive by 100 to 199 this became a much more attractive product as it offered DOS 3 with dual density, but does anyone like DOS 3? I certainly did not and was content to use the dual (medium) density format offered by the 1050 with DOS 2 as amended with the enhancements published in Antic Magazine, August 1984. This gave me 963 single density sectors (120K data) instead of the original 720 (90 K data), a non-standard approach but it represented about 33% improvement.

Finally I have just received the US Doubler (US meaning UltraSpeed) from ICD Inc. This is a package containing two custom integrated circuit chips and a new advanced DOS called SpartaDOS. The new chips are straight replacements for two originals on the 1050 PC board and very full instructions for their removal and installation are given. Believe me, it is really very easy. No soldering was required, I had merely to pull out the originals and push in the replacements. Now my 1050 drive is a true double density (180K data) drive whilst still offering the original single and dual density formats and full compatibility with other DOS's is maintained.

The US Doubler package costs $79.95 direct from ICD Inc., and may now be available from their UK distributes Zoomsoft.

So for the cost of the 1050 (about 200) plus the US Doubler (about 70) we can at last have an economical true double density drive. You should be aware, however, that opening up your disk drive will almost certainly make your warranty null and void.

SpartaDOS is a completely new DOS for the Atari that ICD claim to have modelled on the IBM PC-DOS. It supports single, dual and double densities, single and double sided 5" and 8" disk drives and even claims to be ready to support a hard disk drive when it becomes available. It also contains a special stripped down DOS using very little memory for loading game disks.

Most of the SpartaDOS functions are resident in RAM and therefore no data is lost when switching to and from DOS. However it does take up about 1.5K more of your scarce RAM and you might want to consider using DOS XL instead especially if your main programming language is BASIC XL. The big advantage claimed for SpartaDOS when used with the US Doubler is that it writes and reads three times faster than DOS 2 or DOS XL.

As a test I loaded and saved 'House of Secrets' (one of the longest programmes ever published in Page 6) under DOS 2, DOS XL and SpartaDOS five times and averaged the results:



DOS 2 (with verify) 20 secs 55 secs.
DOS 2 (without verify) 20 secs 20 secs
DOS XL (single density)  20 secs. 21 secs
DOS XL (double density) 16 secs. 18 secs.
SpartaDOS 7 secs.  10 secs.

Whilst this might not be an ideal test it clearly shows that SpartaDOS does indeed perform I/O operations at a much faster rate, it reads about three times faster than the single density DOS's and writes between about two and five times as fast. Think how much time you can save using this DOS and in double density too. You could save wear and tear on your disk drive and halve your disk costs!

A full review of SpartaDOS will follow when I have been able to understand and appreciate its advanced facilities.

I am very pleased with the US Doubler package and can unreservedly recommend it to you.


ICD Inc., 

828 Green Meadow Avenue, 


Illinois 61107,



46, Huntsworth Mews,  

London NW1 6DB