Texas Instruments TI-99/4A video RAM fix

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▶Neol's Retro Lab's initial TI99 video: • TI-99/4A - Powering Up...
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00:00 Introduction
01:44 Reproducing the fault
04:02 Inventory of peripherals
05:45 A look at the motherboard
10:37 Diagnosis and repair
14:49 Power-on test
16:00 Fully reassembled
17:44 A proper test
18:07 Attempting to program in TI BASIC
20:22 Munchman and another strange quirk
24:39 Summary and conclusion
Soldering and test equipment:
● Hakko FX-951 T12 soldering station: uk.farnell.com/hakko/fx951-64...
● Best BST-863 hot air rework station: www.banggood.com/BEST-BST-863...
● Anesty (Duratool) ZD-915 thru-hole desoldering station: cpc.farnell.com/duratool/d006...
● Hanmatek DOS1102 dual-channel oscilloscope: www.amazon.co.uk/DOS1102-osci...
● Amtech NC-559 Tacky Flux: store.rossmanngroup.com/index...
● Goot Wick Desoldering Braid: store.rossmanngroup.com/index...
● Cynel Sn60Pb38Cu2 Tin/Lead Solder Wire: www.tme.eu/gb/details/lc60m2-...
● SysCheck v.2.2 by tf_hh: www.abbuc.de/component/jshoppi...
Equipment and software used for video production:
● Open Broadcaster Studio: obsproject.com/
● 2x Logitech Brio webcams: www.amazon.co.uk/Logitech-Gam...
● USB AV/s-video capture dongle: www.amazon.co.uk/Ex-Pro-Grabb...
● 135W Photography Studio Softbox Light: www.ebay.co.uk/itm/135W-Photo...
● Final Cut Pro
● Apple Motion
● 15" mid-2015 Apple Retina MacBook Pro
#atari
#retrocomputing

КОМЕНТАРІ: 29

@cbmeeks 12 днів тому

The TI-99/4a was my first computer. I have many of them now and still use them. It really is a strange computer that you either love like me, or hate. lol

@adamv242 17 днів тому

A lifelong Atari fan, I always had a fondness for the TI as well. Great keyboard, a very nice built-in BASIC.

@flashjazzcat 16 днів тому

I really liked this machine too, which is why the various puzzling design decisions regarding the keyboard editor, etc, are so frustrating.

@tenminutetokyo2643 14 днів тому

Nice lighting!

@flashjazzcat 14 днів тому

Thanks!

@mikegage3326 15 днів тому

Nice work.

@flashjazzcat 14 днів тому

Thanks!

@jonathanwhiteside6092 15 днів тому

Of all the computers I own, I have to say that the TI 99/4a has the best video signal of them all in unmodified form. I use a CoolNovelties component cable via an OSSC to HDMI and the image quality is unmatched other than by machines like my 65XE and 800XL that have VBXE's fitted. Weird machine though.

@cathrynm 15 днів тому

Suspect TI had decent analog engineers around at the time they designed this machine.

@flashjazzcat 14 днів тому

Seems so, yes. I've been reminded of the RGB mod for this machine, which is apparently sublime, but not having even seen component first hand, I'm sure it's excellent given the quality of RF out of the box.

@JoseArzacSolis 15 днів тому

My first computer was a TI-99/4A. I loved it. The packaging, manuals and documentation were excellent. And I did use a tape recorder to store programs, but I never got a voice synth.

@flashjazzcat 14 днів тому

Yes: presentation was generally excellent. Just such a quirky machine with the benefit of hindsight.

@NotMarkKnopfler 14 днів тому

To delete a character, move the cursor back (fctn key and S key) on top of the character, then press fctn 1 (DEL). Easy when you know how 😅 still not as complex as the spectrum keyboard 😊

@flashjazzcat 14 днів тому

LOL - thanks for that. Easy when you know how, as you say. :D

@PG-gs5vb 15 днів тому

You have to put a chatty dwarf inside the speech synth box to make it work.

@flashjazzcat 14 днів тому

Ah - I did wonder. :)

@ukcroupier 14 днів тому

The RF signal on mine is superb too, actually better than the component using coolnovelties cable (not a dig at coolnovelties, i think the machine is just built that way)

@cbmeeks 12 днів тому

On the speech synthesizer, the door does nothing. It was meant to accept new speech ROMS but that never happened. And as for the joysticks...they are quite awful as you will soon discover. LOL

@MoparStephen 16 днів тому

I wonder if rufies can erase the TI's 16k of memory? Bill would know!

@flashjazzcat 14 днів тому

Not according to the Pennsylvania Supreme Court, LOL

@NotMarkKnopfler 14 днів тому

The PAL TI-99/4A outputs YUV from its video connector. Maybe that's why the cable doesn't work?

@flashjazzcat 14 днів тому

You mean that the component inputs on the TV might be particular about it being YPbPr instead?

@joopidema 13 днів тому

There is a fix for that Alpha Lock problem using a diode.

@flashjazzcat 13 днів тому

Really? I assumed this was by design owing to signal contention with the joystick or something. Nice.

@jasejj 14 днів тому

This was a capable and interesting machine, but unfortunately it was never going to work in the UK. We used tape for games in the early days, and typically never bothered to expand our machines. Out of the box, the TI was completely unsuited to games thanks to the machine's inability to run machine code from BASIC, which immediately prevented good quality cassette based games from being available. I thought at first that this might have been my friend's machine from back in the day - as there can't have been many of these in the North East (friend lived, still does, in Sunderland). His dad was a massive Sanyo fan so it surprised me even at the time that he ended up with one of these rather than an MSX!

@flashjazzcat 14 днів тому

Stuff comes in from all over the country (and world, in fact), although I do get the odd local client coming down to the house in a car. This one was posted in last year from somewhere in the UK, but I suppose you never know where this machine's been during its long history.

@NotMarkKnopfler 14 днів тому

The door on the speech synth doesn't serve any function. The original intention was to produce different voice ROMs with male/female voices and different vocabularies etc. but it never came to fruition.

@flashjazzcat 14 днів тому

Ah - thanks. So it's bascially just a handy storage compartment. :)