Aston Caption Generator

[PaulM]

These caption generators were a 'quiet revolution', which is why we're so keen to see at least one of our examples preserved and running into the future. Kit like this doesn't grab any big features or following, but they're important.

Our 'DICE' (Digital Intercontinental Conversion Equipment) is another significant development that needs highlighting. It represents the beginnings of digital television in the form of a two-way all-digital TV standards converter. Remarkable for early 70s TTL tech! Designed by the IBA, so the BBC stays quiet and the IBA is gone . . .

The Aston was part of that early digital revolution. Nothing like as sophisticated or as complex as DICE, but a little gem of a game changer nonetheless. Some would say that what it did was 'inevitable', but that word is not liked in the history of science and technology. Nothing is ever truly 'inevitable'.

It's sometimes said that TV took decades to 'learn computers', but the computer world 'learned TV' (for graphics), almost overnight! The early Astons were part of that bridge between TV and computers.

Best regards,

Paul M
www.becg.tv

[Patrick Dixon]

The guys that worked on 'DICE' wanted to call it Converter Using New Techniques, but were overruled I was told.

I didn't work on DICE but I did work on ACE for McMichael after they acquired the license from the BBC.

[Red to black]

Originally Posted by Patrick Dixon

The guys that worked on 'DICE' wanted to call it Converter Using New Techniques, but were overruled I was told.

Ha ha Nice one! cool name

[paulsherwin]

No more of this rudery please.

[red16v]

I have asked a retired colleague who used to work on this kit and he informs me our company had a dedicated dual disk drive unit from Aston to copy font disks. If he discovers anything else I will pass the information on.

[cmjones01]

Originally Posted by PaulM

Greaseweazle looks like it might work - given a fair dose of time - and 'dd' looks like a potential tool too. It's stirred some memories that we did try 'dd' back in the late 90s on a Silicon Graphics Unix box (an Onyx) at my employers, but it didn't work.

Greaseweazle and dd are very different tools. The Greaseweazle works at a very low level, recording, analysing and writing the individual magnetic flux transitions on the disc surface. That means it can deal with arbitrary disc formats, even those not supported by the host computer and its operating system. That's important for some computers like the Apple II, Mac 800k, Amiga, Commodore PET and 64 and others, which don't use formats supported by standard floppy disc controller chips. This may or may not include the Aston format, but the Greaseweazle is the tool for finding out exactly what's on the disc.

'dd' on the other hand is just a tool for copying chunks of data around from one device to another, once those devices are supported by the computer's operating system. It knows nothing about floppy discs itself. 'dd' is convenient for taking a sector-by-sector image of a disc and then copying it to another one, but it will only ever handle disc formats which are fully supported by the operating system and its disc controller hardware. This pretty much limits it to the basic MFM and (sometimes) FM disc formats. It won't help with figuring out what format the data is on the disc, and it won't handle anything non-standard, or any copy protection.

Chris

[paulsherwin]

Chris is quite correct. The only reason to try 'dd' (and other standard Unix tools) is it's quick and easy if it works. If you need to get right down inside the hardware you'll need something like Greaseweazle.

[JohnBHanson]

USB Floppy drives are restricted to 512 byte sectors.

Soft Sectored disks can have sector sizes from 128 bytes to (typically) 1024 bytes in
powers of 2. With soft sectored disks there is a sector header that encodes the head/cylinder/sector number. In addition soft sector disks can be recorded at either
250 or 500 bps. In addition there is double/single density to consider.

Of course there are several sizes of floppy - 3, 3.5, 5.25, 8 inches.

Hard sector disks have additional holes to count the sector position. These are much
harder to get hold off as the number of holes depends on the number of sectors/track.

How much data do you have about the floppy disks and the recording format?

[ortek_service]

There's also Single and Double sided, and total number of tracks per side / tracks per inch
- Usually 40 / 48TPI or 80 / 96TPI for 5.25" but were also earlier 35T (still 48TPI?) and 77T (96TPI?) for 5.25" disks.
3.5" ones tended to all be D/S 80T / 135TPI, but may also be some early S/S drives (possibly 40T?), as used in the ST

Plus as well as Single ("FM") and Double ("MFM"), there's also "High" / "Quad" density.
With High Density 5.25" ones usually being 1.2MB - so weren't quite as high as 4x the original 360KB S/S DD 'PC Standard'
But 'HD' 3.5" ones were usually 1.44MB so 2x previous 720KB DD 'PC' ones.
Although Acorn had even-higher 1.6MB 3.5" HD disks as they started off with 400KB for D/S 80T SD disks

This is usually achieved by doubling the Number of sectors per track and hence the bit-rate at the same RPM speed. Although the SPT may not be constant across the disk, and Apple-Mac's originally used variable speed across the disk for constant bit rate density (like with CD's)
Some 5.25" FDD's also had different speeds like 300 / 360RPM depending on whether High Density was being used.

High Density usually also requires special different magnetic-coercivity coating, that might not work too well if used on lower density drives with reduced write current.

Luckily, Hard-sectoring was only used with older 8" and some early 5.25" disks, with later ones just having a single hole to create an index pulse (Although Commodore didn't use this hardware Index pulse on their early 5.25" systems)
With 3.5" disks have a 'keyed' centre metal part, so the FDD itself could generate the index-pulse without needing a hole through the disk.

3.5" disks were probably the most standard in terms of usually always being D/S and 80T / 135TPI. So just all the other variables to worry about.

[TonyDuell]

There were 40 cylinder 3.5" disks but as 'ortek_service' implies they were rare.

Hard sector 3.5" disks are impossble. The index signal is taken from the spindle motor, not from a hole in the disk. So you can't have a pulse at the start of each sector.

Can you look inside the caption generator at the board that the floppy drive connects to? Any recognisable 'large' ICs? If there's a standard floppy controller chip then it's very likely that it uses normal-ish FM or MFM encoding. If it's a mass of TTL, PROMs and maybe PALs then all bets are off...