A disk drive could transform your Spectrum
system, says SIMON N GOODWIN in the first ever. review of
Sixwords. Amstrad-beating Swift Disc - cheaper and
more flexible than the +3, he says.
IN SEARCH OF THE PERFECT DISK DRIVE
THE SWIFT DISC system was developed last
year for a large company which eventually lost interest
in the Spectrum. The inventors - 'big computer
designers - decided to press on and sell it themselves.
The system began as an easy- to-use combination of a
standard disk interface and a press-button copier like a
Multitace. Its since grown in power, but the
original core remains.
The interface is a black box with connectors for a
Kempston joystick, serial printer and up to four standard
disk drives. You use your Spectrum or 128 as normal, with
the interface connected.
The fun starts when you press the button ot the back.
Whatever program you were running is suspended, and the
disk system says hello. You can then use any of the SWIFT
DOS commands. For instance, SAVE 0;FRED 7 will save the
entire contents of memory on disk zero under the name
FRED. The data is not compressed as it is in a Multiface
file, but ybu can still get 13 48K images, or four 128K
ones on a disk.
The '7' in that command is the screen border colour to be
set when the program is reloaded. If you type an 'S'
after the filename, only the screen is saved. 128 users
can choose between its two possible screens. You can save
the contents of any memory area similarly.
LOAD fetches programs, screens or code from disk. QUIT
lets you restart the loaded program, with its display
intact. * resets the computer; ERASE deletes disk files,
unless you've used KEEP to protect them against
accidental erasure. You only need to type the first
character of a DOS command. If you miss out parameters -
for example, if you just type L - the system will ask you
questions to obtain any other information it needs.
ALTER lets you edit program memory, so you can use all
the POKES published in CRASH PLAYING TIPS without
resorting to loading tricks or a Multiface..
FORMAT makes a new disk ready for use. It takes about two
minutes to set up a 640K disk. When you format a disk you
must specify the maximum number of files it can hold -
the default is 32. Larger numbers slow things down and
gobble up some file space.
CATALOGUE comes in two variatons: the BRIEF form tells
you the name of each disk file, the date it was created,
the size in 256-character sectors, and the file type. The
FULL listing also tells you the code address, start or
record size of each tile.
MOVE and BACKUP transfer files, or entire disk coitents
including empty spaces, between disks. This is a slow
process, involving much disk-swapping if youve only
got one drive: data is copied in 4K chunks to avoid
disturbing the computers main memory. Its
often quicker to copy files by loading and saving them
Version 1 was ace for gamesters, but of limited use to
programmers and other serious users. Version 2 added
commands available from BASIC to the DOS commands called
up by the magic button.The disk BASIC syntax is rather
erratically recorded in both the manuals I received, but
its easy enough to work out with a little
Most disk commands are distinguished by a per cent sign
before the disk or channel number. This is simpler than
the microdrives *"m";1; though OPEN and CLOSE
look odd with extra percent and hash signs after the
automatic hash that comes with the keyword.
You can LOAD, SAVE and MERGE programs, screens, code and
arrays, just as with cassette but much faster. LOAD reads
about 7K every second, if you LOAD a memory file created
by SWIFT DOS it runs automatically.
Unlike Amstrad's +3 the Swift Disc can OPEN files. You
can use up to four tiles at once, though they must all be
on the same drive. They can be normal text files,
processed with PRINT, INPUT and INKEY$, or random-access
files with fixed-length records, passed back and forth
with IN and OUT keywords. The BASIC interpreter can only
process files at about 0.5K per second.
A file can be opened at the start or the end but you
cant rewind or move about in a text file, and
theres no way to discard data from the end without
creating a new file. The %EOF function lets you detect
the end of a file, but you cant trap other errors
without a toolkit.
You may run into problems if you CLEAR low addresses when
using Swift BASIC. Theres no check on the amount of
free memory when you type in a program line, so you may
get stuck editing a line if the system can't find enough
room to convert it into tokens.
Swift includes a FORMAT command for its printer port,
which lets you LPRINT and LLIST at any speed to any width
of serial printer.
MICRODRIVE EMULATION - A REASON TO BUY?
Serious users will be especially ompressed by the
microdrive emulator, a new feature of version 3. This
lets you run commercial microdrive programs on disk
without changes. You dont need Interface 1 or real
microdrives, though an Interface 1 manual is useful if
you want to develop new microdrive programs - Swift
doesnt document the Sinclair drive commands.
The microdrive emulator is easy to use. It takes about
four seconds to load a file called EMUL, which stores a
close imitation of Sinclairs microdrive system in
the disk-interface RAM. Swift DOS and Swift BASIC are
disabled and replaced by microdrive commands just like
those provided by Interface 1.
The main difference - apart from a massive increase in
reliability - is that FORMAT grabs an area of disk space
and uses it to imitate a microdrive, rather than set up a
real cartridge. The disk area appears as one 128K file
from Swift DOS, but when the emulator is loaded CAT shows
you upto 50 fiIes 'inside' that area. Four
pseudocartridges fit on one disk, and you can use them
all at once.
The competing Disciple disk system makes a brave attempt
at microdrive emulation by recognising microdrive BASIC
syntax and the hook codes, microdrive system calls
provided by Sinclair. Unfortunately 'real' machine-code
programs like Tasword 3 tend to leap directly into
interface routines. Only the Swift Disc can cope with
this, by mimicking the Interface 1 code right up to the
point at which data is about to be read or written.
I tried out a prerelease version of EMUL with all the
microdrive programs I could muster, and it worked
remarkably well. I had no trouble creating disk versions
of the programs by loading the emulator and following the
All the programs loaded and saved disk data files without
trouble. Besides Tasword I tried Cheetahs Sound
Sampler, Powerprint 2, Beta BASIC, HiSoft Pascal 1.6M,
Oasiss Laser Genius, MIRA Pascal (a new compiler,
reviewed here next month), Discovery/Gremlins Code
Machine 3.1 and its parent, Picturesques EDITAS
CAT options, multifile assembly and other tricky
operations worked fine.
The only things that went wrong were file ERASE
operations from Tasword and Sound Sampler. Both programs
ignored the command. Swift says that a misplaced
instruction in the emulator has since been moved, and
that ERASE now works even if the microdrive ROM is called
The microdrive emulator is a powerful incentive to buy a
Swift disk, if you already use microdrive software - or
would like to but can't stand the cartridges.
At the moment EMUL runs at about the same speed as a real
microdrive, though CAT and ERASE are noticeably faster.
Swift is still fine-tuning the code, and plans to double
the speed of many file operations by interleaving data
inside the pseudocartridge.
The Swift Disc interface uses the same black plastic box
as Sinclairs Interface 1 1with the words 'Sinclair'
and 'ZX Interface 1' filed off and replaced by plastic
stickers. The interface fits the original Sinclair
Spectrum models well, but its a very tight fit on
the Amstrad +2.
A Kempston joystick socket skulks at the back of the box,
where the Interface 1 serial plug used to fit. Some of
the original holes in the case have been cut out to make
room for different connectors. The disk-drive socket
sticks out where Interface 1s network sockets used
The disk connector is the same as that used by the BBC
Micro and QL, among other machines, so theres no
shortage of alternative drives. You can plug in up to
four modern 3.5-inch or 5.25-inch drives; the software
automatically adjusts to different drive formats.
Some old drives cant switch tracks fast enough;
Swift only allow drives 0.006 seconds to step from one
track to the next. The Disciple interface copes with
slower drives, but you must load a configuration file
whenever you start to use it. The Disciple also limits
you to two drives.
Alongside the Swift Disc connector is an edge connector
for other Spectrum peripherals. You can plug in anything
that doesnt use a magic button to interrupt the
computer, and Swift hopes to remove even this
After all this standardisation the pdnter port comes
almost as a relief to Spectrum fans used to the way
Sinclair defied convention. The port uses the ultimate
obscure socket - a modified Microdrive edge connector!
Swift didnt send an adapter (£14.95), despite
requests, so I cant say how well it works. The
company says its much like the port on the
Interface 1 - in other words, OK for driving an RS-232
printer, but tough going for anything else. ZX and
Aiphacom printers still work.
You can plug a genuine Sinclair Interface I into the back
of the Swift unit and run microdrives and disks at the
same time. You cant use real microdrives while
youre using the microdrive emulator, for obvious
reasons, but Swift supplies a program to move the
contents of a tape into a pseudomicrodrive automatically.
The Swift contains 8K RAM and 16K ROM. The ROM is split
into 4K sections, with space for up to 32K. The entire
system, including the disk and printer pods, is hidden
under the Spectrums 16K ROM unless the DOS is in
use. This makes it hard for protected software to detect
and disable the interface; I have yet to
find a program that wont SAVE to disk properly.
The circuit board is crammed into the Interface 1 box
with no room to spare. Its well-engineered but
crying out for some morespace. Swift intends to use its
own box eventually, saving space and money by redesigning
the logic circuit to use custom ULA chips.
BEATING THE OTHERS AT A BARGAIN PRICE
The Swift Disc is very competitively priced, probably
because its only available direct from the
manufacturers - there are no retailers to pay.
The interface costs £76 on its own, and £149 with a
separate 640K 3.5-inch drive and power supply.
Thats a bargain price for the drive - youd be
hard put to find another similar unit for under £100.
The Swift system competes with the Disciple interface,
which Franca Frey reviewed in CRASH Issue 38. The
Disciple costs £90 without a drive. Both systems load at
similar speeds, but the Swift SAVE is about twice as fast
as the Disciples.
The Disciple has the edge in terms of hardware - it packs
780K, rather than 640K, into a disk (but some of that
space is needed for its configuration file). It has
Sinclair standard joystick and network ports, and a
flexible driver for parallel printers. But the Swift is
easier to use, and significantly more compatible with
Amstrad evidently thinks a Spectrum with a disk drive is
worth £250, or at least £200 - our predicted price for
the +3 this Christmas.
But the +3 has less than a third of the speed and
capacity of the Swift and Disciple. It wont work
with microdrive software, and lacks BASIC file-handling
commands. Most damning of all, theres no easy way
to transfer protected game tapes onto + 3 disks.
Spectrum-specific software may be published in that
format, but Id be amazed to see hit games released
on three-inch disks alone, without tape versions.
The +3 benefits from serial and parallel output ports,
and comes all in one box. In theory its compatible
with the old CP/M business operating system, but
80-column display hardware will be needed for most
programs to work. Frankly, I don't think Spectrum users
need or want CP/M.
THE VERDICT - WORTH IT, IF YOU WANT IT
The Swift Disc is well-engineered and competitively
priced. It's fast, friendly, and uniquely compatible with
existing Spectrum software.
The question is: can Spectrum users afford a £150
upgrade? It's worth it, but only if the restrictions of
cassette are hampering your use of the computer. You DO
get value for money, though - a disk drive totally
transforms your system.
SWIFT DOS COMMANDS
ALTER <address> <value> apply POKES (as for
BACKUP <drive> <drive> copies all files
between two disks
CATALOGUE <drive> /B /F list disk file details
DATE <day> <month> <year> sets the
ERASE <name> erases a file from the disk
FORMAT <name> <files> formats disk for
KEEP <filename> protects a file from ERASE
LOAD <filename> /Addr /S loads a memory image file
MOVE <name> <name> copies a disk file
SAVE <name> /S /CODE /DATAs ave image, screen or
UNKEEP <name> removes KEEP protection
* resets the computer
QUIT returns from DOS to main program
All commands can be abbreviated to their first letter.
<name> + (optional drive number;) filename of up to
SWIFT BASIC COMMANDS
CAT % (#stream,)drive (;B/F)
FORMAT %drive;"diskname" (,maxfilecount)
INPUT #stream; <variables>
Items in brackets are optional, "/" separates