A&B Computing
1st January 1985
Author: Jonathan Evans
Publisher: Phi-Mag Systems
Machine: BBC Model B
Published in A&B Computing 2.02
Is fast tape the answer for your filing system requirements?
Phloopy
If you are fed up with loading files from cassette the chances are either that you are frustrated by its slowness and suspect reliability or that you require serious file handling which is impractical on the tape system (or both).
If you are hesitating to buy a disc drive, it may be the price that is putting you off, or the sheer confusion. Do you need standard size or mini-discs, 40 track or 80 track? Do you need a dual disc drive, or perhaps a double sided single drive? And what is going to happen now that the single density chip controller used by the standard Acorn DFS has gone out of production? The observant may have noticed that Acorn's Electron disc upgrade, new ABC computer and Level 2 Econet all involve a new double density chip. Makes you wonder, doesn't it?
If price is the problem and you don't already have a disc drive interface fitted to your machine, you might consider a fast tape system as an alternative solution. There are two systems on the market that I am aware of. One is the Ikon Ultradrive (upgraded Hobbit) which I reviewd in the October issue of A&B Computing. The other is the Phloopy, distributed by Phi-Mag Systems (Trenoggie Industrial Estate, Falmouth, Cornwall TR11 4RY). There is a considerable price difference, with the Ultradrive retailing at a totally inclusive price of £79.95 and the Phloopy at £147.75 (not withstanding the misleading £99 at the top of their advertisements, which does not include VAT, interface, carriage, etc).
The Phloopy's claim for superiority over the Ultradrive is faster file access due to a much faster data transfer rate, on-board microprocessor and 16K (rather than 8K) filing system ROM which avoids the need for a utility tape. However, as we shall see later, the practical file access time on the Phloopy is incredibly variable, according to how it is used. Its main claim over disc is price, though at around £150 it is not much cheaper than the cheapest 100K systems (with interface) that are now being advertised. The only other advantage I can think of is that the tape cartridges are far more robust and easy to handle than floppy discs - a useful point if young children are invovled in the user of the computer.
Hardware
Anyone who has opened a computer magazine in the last few months will have seen a full colour Phloopy ad explaining its "byte wide" head, i.e. eight track recording, which has enabled them to achieve the astonishing data transfer rate of 10K per second, which is comparable to disc.
Unlike the Ultradrive (which is reel-to-reel), the Phloopy uses a continuous tape loop, but one which they assure me is superior in design to the much criticised Sinclair microdrive. Apparently the latter uses a Centre Tap spindle, whereas the Phloopy uses a Bin Loop, for the benefit of any readers who might appreciate the distinction.
The tape actually has extra tracks which carry redundant information to allow automatic error detection and correction by the built-in microprocessor. It uses random rather than serial access, which means that a complete map of the tape is read each time a filing system command is issued, and a file can be saved and retrieved in separate chunks distributed throughout the tape. For this reason, the tape never needs to be compacted, since all the free space from the front of the tape is automatically filed.
A nice feature of the Phloopy is the on-board microprocessor which performs some operations, such as formatting a tape, while returning control of the BBC computer to the user. Although the system needs to return the recording head to the splice following each filing operation, this is again handled by the microprocessor without occupying the computer's time once the save or load has been completed.
The Phloopy connects to the disc port and requires the fitting of an interface. I didn't have to do this myself since I was loaned a suitably equipped micro for the review, so I can only pass on a summary of the very clear and detailed instructions in the manual (the documentation is generally very good).
Two 14 pin connectors are inserted in the IC79 and IC80 sockets and a much larger controller board into the IC78 socket - the text suggests that lining up the pins might be a bit tricky here. There is, of course, a filing system ROM to be fitted into one of the sideways ROM sockets, and a bit that will frighten some readers - a need to cut the wires leading to resistors R22 and R23. The final step is to connect the ribbon cable to the disc port and the power supply cable to the socket provided on the BBC machine. Although the instructions are clear, with diagrams, some people will inevitably lack the confidence to do it themselves (or be worried about warranty), in which case a dealer's fee must be added to the cost of the system.
Operation
The Phloopy loads and saves files in a completely automatic fashion and responds to all the usual filing system commands (CAT, SPOOL, etc) in addition to permitting use of the BASIC commands for random access such as PTR# and EXT#. A full list of Phloopy's additional commands (all in ROM) is given in Table 1. The manual gives a detailed description of all filing system commands, both general to the micro and specific to the Phloopy. A disc user (Acorn DFS) looking at Table 1 will spot the addition of the useful *VERIFY and note, in particular, the absence of COMPACT and BACKUP. The former, as I have explained, is not needed but the latter would have been useful expecially because *COPY can only handle one file at a time with no wildcards.
We now consider the critical question of the speed of the system which, at the price asked, one would expect to improve considerably on the Ultradrive and approach that of a disc. First impressions are that this is indeed so, until one investigates a little more carefully.
A standard 100K Phloopy cartridge takes thirteen seconds to go around the loop, so this is the maximum time that it can take to load a single program. By comparison, the Ultradrive can take up to 45 seconds when formatted with two catalogues on each side of the (120K+) tape, and it can take up to 45 seconds to change catalogues if you start at the wrong one. Hence the Phloopy shows a big advantage over the Ultradrive but some inferiority to disc unless the program loaded is the first file recorded on the tape.
The big speed advantage of the Phloopy over the Ultradrive may, however, be lost or reversed if a program loads in several parts. This is because the Phloopy can only pick up one file on one spin of the loop, and cannot chain a series of programs recorded in correct sequence at once pass. This does, at least, have the advantage that one does not need to worry about the order in which programs are saved. However, we can begin to see why there is much more involved in file access time than data transfer rate.
We now come to the major weakness of the Phloopy, which is the way in which it handles data files. All filing systems load and save date files slower on the BBC Micro than LOAD, SAVE, LOAD or SAVE operations, because the filing systems is switched off between blocks of 256 bytes. The effect on the Phloopy is, however, much more dramatic than with other systems.
With a single data file open, as when using Wordwise, it manages to pick up (or lay down) about 1.5K and then must do a complete loop before it can do any more. To test the effects of this, I loaded the identical smallish (6.3K) Wordwise file on several different filing systems. A Teac 80 track disc drive took a surprisingly long 14 seconds, while domestic cassette loaded the file in 140 seconds.
The Phloopy took 70 seconds and lost comfortably to the Ultradrive which loaded in 50 seconds (all figures approximate!).
Phi Mag have responded to the Wordwise problem in two ways. One is that they have produced shorter loops for development work. The same file loaded in 32 seconds and 20 seconds on a 50K and 25K loop respectively. The snag is that these short tapes come very expensive for the amount of data they hold. The standard 100K cartridges are fairly pricey in my opinion - £18.11 for 5 or £4.25 bought singly. Both 25K and 50K tapes will sell at £16.95 for 5 or £4.03 individually. The company also tells me that they are developing their own wordprocessor for the Phloopy which they plan to supply free of charge on cartridge when the whole system is bought. I have, of course, no idea how good this program will be, but I understand that it will overcome the slow save/load problem. At my suggestion, the company are now testing View for its suitability with the Phloopy.
Wordwise is not the only user of data files of course, which may be used for saves in games programs and also in users' own BASIC programs for data logging etc. This is where I have to give the really bad news. The Phloopy, like disc and Ultradrive, claims to be able to handle up to five open files at once. Unfortunately, once a second data file is open, the system can only handle one 256 byte buffer per spin of the loop on any open data file.
In one test I loaded a small 3K data file from a BASIC program first with one file open and then with a second opened. The Ultradrive took 28 seconds in either case. The Phloopy (100K tape) took 32 seconds with one file open, but an horrendous 2 minutes 41 seconds with two files open. I am forced to the conclusion that for all practical purposes the Phloopy is a non-starter as a multiple file handler.
Software
Once you upgrade your filing system you will run into problems with commercial software. Some programs are available on disc, but many, especially games, are not. Despite the claims of the advertisements it appears that no commercial software houses have as yet committed themselves to supplying software on Phloopy cartridges. Transferring tape programs to disc runs into two problems, program protection (if present) and use of memory, since the disc system sets page up from &E00 to &1900.
Similar problems arise with the Phloopy since it normally sets PAGE to &1600. The problem is a little easier than with disc since a program can be loaded direct to &E00 if it does not then attempt to load or save another file, and to &F00 allowing chaining of other programs, etc. However, any program which loads below &E00 will need to be "downloaded" i.e. loaded in higher in memory and then shifted down in memory before running.
Phi Mag have provided supplementary documentation to their customers on how to download machine code, as well as BASIC programs. They have also provided a command in their ROM. *TRANSFER, which transfers single files from cassette to Phloopy automatically. Whilst this will transfer a locked file, if protection is found on the original it is also placed on the Phloopy copy. Whilst the company presumably did this to avoid accusations of aiding piracy, it was actually a mistake in my view.
They seem to have entirely overlooked the fact that most machine code games load below &E00 and thus cannot run on Phloopy without downloading. Since a protected Phloopy file can only be *RUN, their (presumably) frustrated customers have no means of *LOADing the copied file in order to download it. There is also a bug in the *TRANSFER routine, which sometimes puts protection onto harmless BASIC programs which then refuse to CHAIN. Such programs can of course be transferred by TRAPE, LOAD, PHLOOPY, SAVE, etc, but the utility provided is more convenient and should work as documented.
Table 1. Commands In Phloopy ROM
*COPY
Copies a single file to another tape either on the same drive or a different drive
*DELETE
Deletes specified file
*DRIVE
Selects drive
*FORMAT
Formats a blank tape
*HELP PHLOOPY
Lists commands
*INFO
Provides parameters of specified file (load address, length, etc)
*LOCK
Locks files to prevent accidental overwriting or deletion (equivalent to *ACCESS on disc system)
*PHLOOPY
Selects Phloopy filing system
*RENAME
Renames specified file
*TITLE
Gives a title to a tape (optional)
*TRANSFER
Transfers a file from domestic cassette recorder
*UNLOCK
Reverses *LOCK
*VERIFY
Verifies saved file with contents of memory
Conclusions
How good a buy is the Phloopy? The sensible comparisons seem to be with the Ultradrive, which is much cheaper, and a disc drive which is significantly more expensive (at least one of a quality worth buying). Firstly, Phi Mag are to be congratulated on achieving a superb data transfer rate equalling, or bettering, disc, and on the use of an onboard microprocessor which has many advantages. They have convinced me, in principle, that fast tape systems could provide some genuine competition in performance with floppy disc systems.
Unfortunately, their current software design does not seem to me to permit the hardware to realise its potential. When programs chain in sections or when one data file is open (as in Wordwise) the system's performance is way below that of discs and, if anything, inferior to the Ultradrive, unless one is prepared to work with the very short and expensive tape loops. Worse still, in multiple file handling operations in which the disc system excels and the Ultradrive is workable, the Phloopy is effectively useless.
How many people need multiple-file handling, the manufacturers will retort? Well, it is needed in serious database manipulation, for example, to keep index files to speed up the computation of access into large masterfiles. True, commercial software written to use such facilities is aimed at disc users, but what of programmers who wish to do such operations themselves? I would imagine that secondary school usage in both teaching computer science and laboratory applications will require this facility, so the Phloopy must concede this potentially lucrative market entirely to discs. The Phloopy might appeal to primary schoools because of its relatively fast program access time and robust cartridges. Whilst much educational software makes use of the datafiles, these are generally single file operations because the software is written to work with ordinary cassettes.
What of home owners? If they are primarily Wordwise users or programmers wishing to do extensive file handling, I would have to recommend that they upgrade to discs if they can afford it, or to the ultradrive if they cannot. If their prime interest is in writing programs which do not make much use of datafiles than the Phloopy will provide very good performance. Whether the system is a good buy for games players is debatable: (a) It's a lot of money to pay for the privilege of loading your games more quickly, (b) there is no guarantee as yet that commercial games will be sold on Phloopy cartridges, (c) a fair proportion of cassette-based programs will prove difficult to transfer onto it anyway.
One thing's for sure, no one should buy the Phloopy without knowing what kind of use they want to make out of the micro, and checking carefully whether the system will be suitable. I think this is unfortunate since one of the big advantages of the BBC Micro is its flexibility. Thus owners might initially buy one for games or educational software, but later get into wordprocessing or serious database management. If they have bought a relatively expensive filing system they are entitled to expect it to cope with the range of filing activities provided by the machine without drastic loss of efficiency.