Spectrum Computing

Following on from this thread (thanks Ast), can we pool some opinions on how these file types should be assigned a minimum model.

My experience of .TRD and .SCL so far has been almost entirely Russian games and the occasional recent one created with the clones in mind. If they happen to work with a less pimped Spectrum*, that doesn't feel** the same as a 1990's 128K game that happens to work with a 16K (which should be assigned 16K IMO) to me.

So, I think these file types should be assigned as minimum model Pentagon 128, unless stated otherwise, regardless of whether they work on a 48K with the appropriate disk interface.

Are there examples of .TRD/.SCL that were created with the 48K/128K Spectrum in mind?

What do we think?

*actually Ast, can you describe how a 48K owner would go about using a .TRD or .SCL?

**and I realise this puts me on a sticky wicket with the technicality of 'minimum model'!

Well, I haven’t gone through all the titles released as TR-DOS images, obviously, but most Russian clones were just that—clones; not so much “pimped,” as just imitations made by reverse engineering the original machines to the best abilities of whoever was reverse engineering them. So, to answer your question

R-Tape wrote: ↑Fri Nov 23, 2018 8:58 pm Are there examples of .TRD/.SCL that were created with the 48K/128K Spectrum in mind?

yes, there are. Perhaps even most of them.

The reason the Beta Disk interface (and TR-DOS, which accompanied it) became so widespread in Russia was the same reason the Spectrum became so popular: jelly-bean components and the availability of the key component, which in the case of the Beta Dis was the clone of the FD1771—a floppy disk controller. Another advantage the Beta Disk interface provided was that it worked with standard 5.25″ disk drives.

R-Tape wrote: ↑Fri Nov 23, 2018 8:58 pm actually Ast, can you describe how a 48K owner would go about using a .TRD or .SCL?

It’s no different than a +3 owner using a .DSK file. You’ll still need a PC app that can write to a floppy disk using the appropriate format. Except in the case of TR-DOS disks, it’s much simpler to implement, because you can use standard 5.25″ or 3.5″ drives and controllers. With +3 disks, the app will have to communicate over the Shugart bus and control a 3″ Hitachi compact floppy disk drive.

After you’ve written your TRD or SCL filed to a disk, you pop it into a disk drive hooked up to a Beta Disk interface connected to your 48K or 128K Speccy, and you’re golden.

In an emulator, it’s just a matter of enabling the Beta Disk option and loading the TRD/SCL image directly.

R-Tape wrote: ↑Fri Nov 23, 2018 8:58 pm I realise this puts me on a sticky wicket with the technicality of 'minimum model'!

I know what you mean, but I think the minimum model requirement should reflect the features of the game—not the medium it’s delivered on.

Consider this: What would you put down as the minimum model for software that was released on a Microdrive wafer or a ROM cartridge? Neither interface came standard with any Spectrum, so should it be “none”? Well, no. It would depend on the software requirements. For instance, the standard IF2 cartridges were 16K, and so the minimum model would be the 16K Spectrum.

I think it’s logical to apply the same reasoning to categorizing TR-DOS software.

R-Tape wrote: ↑Fri Nov 23, 2018 8:58 pm Are there examples of .TRD/.SCL that were created with the 48K/128K Spectrum in mind?

All of my games available in such formats - Al's Double Bill, Funky Fungus, Doom Pit, Seto Taisho Vs Yokai, Seto Taisho To Kazan, Sophia - were designed to be compatible with standard Spectrums equipped with the DivIDE/DivMMC interfaces and ESXDOS 0.8.5 and later revisions. Tests made with Fuse and RealSpectrum also confirmed that some of them, for example Sophia, will also run on a 48K Spectrum connected to a Beta Disk interface, although being originally designed for the 128K, while Al's Double Bill will automatically load the 48K or 128K versions according to the machine it is being loaded on.

some disk versions games at vtrdos.ru made for 48K. As I remember I made an "Emerald Isle" with tr-dos support.

In terms of hardware, we have three (main) things to consider:-

1. Minimum RAM required
2. Hardware quirks that software relies on (if any)
3. Media / expansion system / mass storage system that it loads from

1 is easy, choice of 16k, 48k, 128k
2 is about software using things like the floating bus, or the slightly different ULA/CPU timing etc.
3 is self explanatory.

Mark