Wish: MAVIS computer recreation in Mode 7

[hoglet]

For reference, here's a link to the service manual for the HP 82161A Digital Cassette Drive that includes schematics:
http://www.hpmuseum.net/document.php?hwfile=2835

The decoding looks like it's done in the drive firmware.

I think the question is, how will the drive handle a foreign format tape?

Hopefully it doesn't just automatically re-format it!

Dave

[daveejhitchins]

Circuit's a bit hard to follow without printing it out and joining - but - Couldn't the decoding circuit be bypassed by taking the head output after at the sense amp out?

Dave H.

[BigEd]

Here's the relevant page, I think:

It might even be that this circuit would be relatively insensitive to a different bit cell timing.

[OneSwitch]

As an aside from tantalising tape recovery work, the GAconf (Game Accessibility Conference Europe) in April will have a 15 minute segment on MAVIS.

"MAVIS and the Tomorrow People" at 2:15 pm, on 5th April 2021 - GAconf: https://www.gaconf.com/schedule/

Free to register, or I'll post it up here sometime after.

[OneSwitch]

Wonder if the documentation here may be of use: https://www.dropbox.com/s/g3pdjsjgknyb7 ... 1.pdf?dl=0 for recovering data from the cassettes. I'm trying to get in contact with Tim Folkard who was a key technical member of the MAVIS team. Sadly another team-member, Nigel Bevan died a couple of years ago who may have been very helpful.

[scruss]

"MAVIS and the Tomorrow People" at 2:15 pm, on 5th April 2021 - GAconf: https://www.gaconf.com/schedule/

I'd love to make that, but I've just been let go from work: we ran out of money for my position

[OneSwitch]

"MAVIS and the Tomorrow People" at 2:15 pm, on 5th April 2021 - GAconf: https://www.gaconf.com/schedule/

I'd love to make that, but I've just been let go from work: we ran out of money for my position

Really sorry to hear this, Stewart. Good luck finding something afresh. They'll be lucky to have you.

On the video, GAconf share them all eventually, but as for my MAVIS talk, I'll pop it up here the day after. It's a cut down version of the book chapter, with just a few extra bits popped in to add colour.

[OneSwitch]

MAVIS and the Tomorrow People video here: https://youtu.be/B9bZhSJCbTI, with a nod to the BBC Micro to come at the end. And the fascinating SPOC system.

[scruss]

Lovely. Thanks so much. I've been enjoying GAConf, despite the timezones

[OneSwitch]

A really interesting part of MAVIS surfaced today, thanks to David and Julia Schofield. The MAVIS user manual.



https://www.oneswitch.org.uk/OS-REPOSIT ... manual.pdf

Loads of interesting colour photos and extra detail, including a close-up of the cassette mechanism.

[BigEd]

That's great! It's finally shown me where the cassette drive sits in the briefcase, too.

Some technical clues within:
"Each cassette holds about 60 pages of text or graphics which is about ⅓ of the total volatile memory capacity."
"If a new tape is to be used, it must first be reformatted as instructed in the relevant section below."
"New tapes or tapes having been corrupted require to be formatted. When this is carried out, all information carried on a tape, will be lost. If the instruction 'TAPE NEEDS REFORMATTING' appears, it is suggested that further attempts be made to load the tape before reformatting is executed."
"To Format a tape write FORM on the command line, then confirm and wait until an audible blip announces the operation is complete. This may take up to two minutes."
"TAPE NEEDS RE-FORMATTING. A specific tape block could not be found. This implies either that a block marker has been corrupted or that the tape index indicates more blocks on the tape than actually exist."

[OneSwitch]

Just for curiosity... this fantastic photo turned up yesterday thanks to Tim Folkard (pictured with the sip-puff tube). It was after the succesful demonstration of the MAVIS system, allowing them to move onto the next stage.

Back row -
Julia Howlett, Dick Penn, Tim Folkard, Chris Evans

Front -
Beulah, Rudi Dallos, Chris Goss


Between Rudi and Chris is a prototype FRED robot.

Seeminly The MAVIS Mk I was built by Jasmine / Jasmin Electronics (possibly) of Leicester. Wonder if anyone has any memories of them at all?

[OneSwitch]

Many thanks to BigEd and revaldinho for taking a much better quality image of the 15 Sep 1977 Computer Weekly: "MAVIS - a match for any handicap".

I've had news today of a video turning up, but in U-matic format:

Title on box: MAVIS (VDU Screen in Operation) Date 7 Oct 1980

Duration: 23 mins

Media type: Umatic Low Band, KCA -60

Scenes

An instructional/demonstration series of screens for VDU display. No live action, text and simple diagrams. No commentary.
Demonstrates operation of MAVIS (Microcomputer Audio/Visual Information System for the disabled) Operates by selection from matrix menu on screen by operation of switches adapted to user capability.
Screens include demos. of following: History and brief description of system and possible uses.
Use of matrix selector e.g. telephone dialling, TV channel selection.
Setting up a matrix.
Drawing on MAVIS
Use of text - diary, correspondence, testing reading age, comprehension.
Programs on MAVIS - games, creating tunes.
More about matrices

Fingers crossed there's a way to get this preserved somehow.

[BigEd]

That's an excellent find!