========================================== **************************** * PART 7 - TECHNICAL FORUM * **************************** This issue, I have received a letter: "I am now the happy (?) owner of a Timex disk drive for the Spectrum. I bought it at a sale organised by my university. I also own two Timex 2048 machines. "The drive seems to be some predecessor of the famous FDDЗO00 drive, and I think it is called FDD 3. I have 3 inch and 5 1/4 inch drives connected to the controller. The 3 inch drive came with the controller and the 5 1/4 inch drive came from my old XT. I don't have any manuals for the drive but I have read old issues of Polish computer magazines and there was some information about this drive. It seems I need a diskette with TOS in order to format another diskette, and it seems that the drive controller will not start without this diskette because when the controller starts it reads TOS into its own internal RAM. "The problem: I don't have the TOS diskette. "What I need is an image of a formatted diskette so I could format more and enjoy my old Timex. By "image" I mean all sectors from the diskette written to one 160K file. think I can write a program for my PC to format diskettes to 40 tracks, 16 sectors, 256 bytes per sector, and write this image there. "Does anyone have a TOS diskette for this drive, or an image of it?" DOMINIK BEHR ========================================== Tech Ed's reply: Firstly, with this equipment being marked TIMEX, I would guess it's intended for the American market. Perhaps some of our American readers would be able to help. Second, you mention a 3-inch drive. Do you mean CF2 type? These disks are getting rare, but some people using Amstrad PCWs, CPCs or the Spectrum +3 may know where to get them. If you mean the PC type, these are 3 1/2 inch, and very common. Thirdly, you might, quite possibly, be able to make a 5 1/4 inch PC drive format a disk suitable for the Timex. It might help you, but it might not. Not knowing this drive, I am throwing this query open. If anyone knows how to solve this, perhaps you could let me know. My details are at the end of the technical section. ========================================== TECHNICAL WRITES This month, I have written an article on mass storage devices and ability to emulate. Once again, as a PC user, emulation is generally from the PC point of view. Mass storage is a central part of a computer system. Without it, the computer would forget everything when switched off. The Spectrum was supplied with the ability to use audio tape, usually in the form of the Philips compact cassette, as mass storage. The advantage of this was that it was the one form of storage which was available to everybody, with most people either owning a cassette recorder or going out to buy one when the need was discovered. The +2 and +2A models had the data recorder built in. Tape had the advantage that most retail software was supplied on cassette. The major disadvantages were finding a block on cassette, the fairly slow speed, and, in some cases, poor reliability. Of the emulators available for the PC, several handle tape. SPECTRUM has limited tape handling, and Z80 is well-specified. Others exist, but in most cases are limited. Sinclair planned to launch the Microdrive system in 1982. Unfortunately, it was delayed, and then needed the ZX Interface 1 before it could be fitted. The media was a small cartridge containing a loop of tape. The system was much faster than tape, but access time was still fairly slow. Cartridge reliability was a problem occasionally, and the vast majority of cartridges had at least two bad sectors. Storage capacity was in the region of 90-100K. Up to eight drives could be fitted. Emulators are unable to handle the real cartridges, but Z80 handles a file type called MDR, which emulates a microdrive cartridge. It is reasonably possible to devise a system linking a real Spectrum with microdrives to a PC, and copy cartridges that way. Other mass storage systems began to appear over the years which followed. Rotronics launched the WafaDrive. Some people found these very useful, but the media was somewhat non-standard. Printer interfacing was provided by the drive, which also proved useful to many users. As yet, I have never seen a system emulating the WafaDrive. Storage systems using standard disks proved to be quite popular. The Beta system, which was fairly popular, has the advantage that only a simple program is needed to read the disks on a PC. Kempston, best known for their joystick interface, also launched a system. Miles Gordon Technology designed the Disciple interface, and marketed the +D, which was almost the same thing. The Disciple interface was compatible with the Interface 1 network system, among other things. The MGT interfaces can be emulated easily with some emulators. For the PC, Z80 works well. You may have noticed that I have so far omitted the Opus Discovery. There were two different models, one which had one drive and a joystick port, upgradable to two drives, and one which had two drives and no joystick port. A parallel printer port was included, which used the same commands as the Interface 1 serial port. The Opus, in common with many of the other systems, used a BASIC command set similar to that used by microdrives. Most did suffer due to them not being microdrives, and some things were different. Some used a completely different set of commands, the WafaDrive almost setting the standard. The Opus system used 40-track 3 1/2 inch disks. The major disadvantage of these is that it is difficult, if not impossible, to make 80-track drives read the disks. Some systems which were upgraded rather late in time were fitted with an 80-track second drive. These are the exception, rather than the rule, and are not worth emulating. The only other system I knew of for the older machines was the Clive Drive. This was VideoVault's 3-inch drive, which may have used MGT firmware. An attempt to make a standard disk drive for pre-+3 systems, it was a failure. The +3 included a CF2-type drive. A fair amount of software was released on disk, and this was as close as could be got to a standard. The +3 would take an Amstrad FD1 as a second drive. The +2A was intended as a "lower" machine that could be upgraded. The SI1 and up to two FD1s could be attached. I have never known of one of these being used. Many users wanted a way to transfer their software, in particular, games, to the high-speed devices. Some solutions using convertor software existed, but some programs could not be handled. Some very old games could easily be hand-blocked. Some included instructions for transferring to microdrive, and these functions often worked with the other drives using microdrive commands. Probably the most effective solution came by way of the Multiface. Created by Romantic Robot, various versions existed, and any program could be stopped and saved to certain media. The disadvantage, just as with snapshotting on PCs, was that the randomness of certain programs could be affected. The Multiface 1 is emulated by SpecEm, and Z80 emulates the Multiface 128. Some disk interfaces, notably the MGT ones, included an NMI button, which allowed built-in snapshot creation software to run. ========================================== TECHNICAL NEWS Following the release in issue 2 of SpecTest, version 2.95, a new feature has been added, and a bug in one of the machine code routines corrected. Version 3.0 is included with this issue. It will now test all memory above 16K on the Sinclair 128 and Amstrad's +2. In order to make the program remain compatible with 16K systems, and those with microdrives, the BASIC part has been modified to take up less memory. Technical editor, Phil Reynolds, can be emailed: phil@hedgford.demon.co.uk, or faxed: (+44/0) 1543 428082. Technical queries will generally be answered in the following issue of Emulate. ==========================================