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binarydinosaurs.co.uk
Binary Dinosaurs
@binarydinosaurs.co.uk
1.1K followers 120 following 1.9K posts
Collecting, repairing and preserving vintage machines since 1998.

W: https://binarydinosaurs.co.uk
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M: @binarydinosaurs.oldbytes.space

"The king of old weird stuff" - Fuzzweed.co.uk, Nov '25
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binarydinosaurs.co.uk
Since I’ve done the PT502 then let’s also have its predecessor, the PT501. This was a microprocessor trainer SBC and came with a stack of books that look impressive but just try to cover the whole gamut of computing for the absolute beginner.*

This one is serial 6969.
Since the OU didn’t have classrooms you learnt at home meaning the computer kits were mailed to you in boxes like this. The little PT501 on top of the Experiment Book which has some example code and explainers on how it works. Serial number label. It says GR6969. A pretty rainbow of all the books that came in the box with the machine. They all have a PET on the front but one of them tries to describe a mainframe which seems a bit of a stretch to someone learning how a microprocessor works.
January 17, 2026 at 2:04 PM
binarydinosaurs.co.uk
I needed to test some 8085 CPUs, @devilishdesign.bsky.social suggested the Open University PT502, aka HEKTOR. Splendid. My Hektor pics are 24 years old so it’s time for some new ones.
Note to self, don’t put your tongue on that fuse on the PSU because it’s 240v 5A 🫣💥
The Hektor-II complete with its Curry’s tape recorder and a blinkenlights experiment board. Plus that lovely PSU with live contacts on the top. They should have a plastic cover but I’m guessing that was one of the first things that got lost. Hektor is an 8085-powered machine for learning how computers work, it was the follow up to the single board PT501 CPU trainer which only spoke hex. The spacebar key switch is very broken, and replacing it will be a proper pain so I’ll leave that until hektor is going to go on display. Don’t put your tongue on that fuse when it’s switched on.
January 17, 2026 at 12:19 PM
binarydinosaurs.co.uk
I do like getting these in the post. We can play a game of ‘which particular mangling of the name TEXTOOL will it be this time?’

So far I’ve seen

TFXTDOL
TEXTOQL
TEXTODL

any more?
A clone of the mighty 3M TEXTOOL ZIF socket, this one is a TEXTODL because of course it is.
January 16, 2026 at 1:52 PM
binarydinosaurs.co.uk
The Philips P2000C portable doesn’t have a plain video feed to its CRT, it has a terminal which talks to the main board via RS232. It also has an external monitor connection as well as the internal one.

In my machine’s case, the external connection has a video signal but the internal one doesn’t.
The P2000C’s terminal board, a separate computer with its own Z80, RAM and ROM. At the top of the board is a red socket where the internal monitor plugs in. Below it is a set of pins denoting where the external socket is soldered. I’ve plugged in a monitor and I can see the machine works fine but the internal CRT does nothing. I’ve discovered the video feed to the internal CRT is dead so it’s time to get the scope onto each pin in the path to this socket. Fortunately Philips provided full schematics and circuit descriptions for everything except the CRT, which is a Mitsubishi NT-1002XU. Zero documents about that online.
January 10, 2026 at 12:57 PM
binarydinosaurs.co.uk
Can I keep it? It followed me home 😁

(Cheers to @petescircuit.bsky.social for the tipoff)
The Philips P2000C portable computer from 1982. It’s about the same weight as the Osborne 1 and Philips were so confident in its portability that they gave it a carry strap. The manual is sitting on top of it. Keyboard and a piece of foam that amazingly hasn’t fallen to pieces, this sits between machine and keyboard to protect both from each other while in motion. Keyboard feels very membrane-y but has a nice action. The front of the machine, showing the CRT, twin TEAC FD55 drives and because Philips a broken power button. Fortunately it’s stuck on and this is how the previous owner got it to explode. Hopefully just a tantrum on the 12v rail. There’s a gap between CRT and floppy drives where floppies can be stored so I’m assuming the CRT is shielded 😄 A view of the whole front of the machine. It’s very clean and tidy and non-yellowed.
January 4, 2026 at 6:20 PM
binarydinosaurs.co.uk
What’s got two thumbs and has just spent half an hour zapping EPROMs only to realise it didn’t turn the bloody lamp on 🫣😆
Picture of a ‘stag’ EPROM eraser from the 1990s so it’s a lovely shade of brown. Hard to believe it used to be cream coloured. In front of it is a pair of 2764 chips destined for a Camputers Lynx from 1984.
January 4, 2026 at 1:12 PM
binarydinosaurs.co.uk
Question. The STC Executel 3910 has an Intel D8741A microcontroller for the tape drive. If you remove this controller from the machine it stops everything. No address or data bus activity. Nothing. Only the clocks are active.

Datasheet doesn’t give me any clues as to why this might be. Anyone?
January 3, 2026 at 1:02 PM
Reposted by Binary Dinosaurs
bluescsi.com
Announcing BlueSCSI Ultra, Ultra Wide and (coming soon) SCA.

bluescsi.com/ultra
BlueSCSI Ultra & Ultra Wide Announcement
Announcing BlueSCSI Ultra and Ultra Wide - 68-pin 16-bit Ultra Wide support, integrated RP2350B, Front Panel support, and more.
bluescsi.com
January 2, 2026 at 11:04 PM
binarydinosaurs.co.uk
Happy new deer everyone. Having stared at this deer's face for far too long whilst working on the pic I can't help but think it's a bit miffed about the state of things.

Never mind. Just half a day's debauchery to go then it's back to the grind. Cheers 🍻
Photoshopped pic of a deer with nice smily new teeth and a 'NEW!' sticker on its side. The strapline is 'Happy New Deer' and I've put a little exploded capacitor in the top corner since that appears to be my logo now.
January 1, 2026 at 12:24 PM
binarydinosaurs.co.uk
#ExecutelJapes it’s been a while since I’ve had an Executel 3910 on the bench, thankfully my Copious Notes helped setting things up a bit. Here we can see an immediate issue with AD0, AD1 and AD3 being so scatty they’re not recognised as active by my HP 1660a logic analyser. /2
The tendrils of the logic analyser are surrounding and probing the Intel 8085a CPU of the Executel 3910. Lots and lots of wires, and it’s only going to get messier as time goes on. HP1660a logic analyser screen showing which lines it’s tracing are active. Underneath ‘master clock’ there’s a series of arrows showing everything is active apart from pins 3, 1 and 0 on Pod1. These lines are mapped to AD3, AD1 and AD0 respectively.
December 31, 2025 at 6:55 PM
binarydinosaurs.co.uk
Because it's the quiet time of year, and because I have two more STC Executel 3910s in for repair I thought it was high time I redrew the first schematics I did manually back in 2017 using Fritzing, finishing JUST before I was given the originals 😆

KiCAD doesn't have a Fritzing importer, soooo...
KiCAD schematic of the CPU, Timing, Clock, Tape and LUCY (SAA5070 viewdata display controller) of the STC Executel 3910. It's not electrically complete by any means, and some of my pin assignments are dodgy but it almost passes the rules checker if you exclude some gaping violations 😆
December 27, 2025 at 7:45 PM
binarydinosaurs.co.uk
Nowt like the brisk Norfolk coast to blow away the cobwebs of a Boxing Day. A few hundred other people also had the same idea 🌞
View south along the front at Hunstanton, tide is on the way out. Lovely day for a walk in the sea breeze and it seemed like a few hundred other people had the same idea.
December 26, 2025 at 2:37 PM
binarydinosaurs.co.uk
Happy Xmas you lot, I've dressed up an exploded RIFA accordingly.
A photo of an Astec power supply where the mains RIFA transformer has utterly exploded - this one took the mains fuse with it. But all was well afterwards so I've put a Santa hat on it because it's Xmas.
December 24, 2025 at 7:57 PM
binarydinosaurs.co.uk
Also, a series of one that I call 'accidental usage of depth-of-field' taken recently while testing a Mac LC475 thanks to a monitor @devilishdesign.bsky.social gave me. The RAM stick was dead which is why I was getting mournful tones from the machine. No recapping currently required.
Picture of a Mac LC475 with its top off being powered by a CR2032 battery otherwise it won't display anything. On the right is a 14" monitor showing the MacOS 7.5.1 desktop and between the two is a bad stick of RAM that was stopping the machine booting.
December 21, 2025 at 8:17 PM
binarydinosaurs.co.uk
My microscope was almost aping a Speccy today 😄
Picture of an Andonstar microscope screen accidentally focused on a ribbon cable that happens to be rainbow coloured, a bit like a ZX Spectrum but the wrong angle.
December 21, 2025 at 8:06 PM
Reposted by Binary Dinosaurs
jcs.org
a dumb idea i had yesterday
December 18, 2025 at 10:46 PM
Reposted by Binary Dinosaurs
vintagecomputer.ca
Both of my DEC DTC01 Voice synthesis units are working great now. As such, I put a little demo of one of them singing Jingle Bells for the holiday season and #DOScember. I am using an IBM PC AT and Telix as a terminal to run a script.
youtu.be/n5BuiTxDFHY
#vintagecomputing #retrocomputing #DEC
Demo of the DECtalk DTC01 Voice Synthesis Unit singing Jingle Bells
YouTube video by vintagecomputer.ca
youtu.be
December 19, 2025 at 12:12 AM
binarydinosaurs.co.uk
#holidayOsborneJapes

I’ll let the pics do the talking. Basically both floppy drives are toast but I worked out the magic runes to get the Gotek working as drive B.

Splendid. So, APART FROM the keyboard and both floppy drives the machine is working 😆
The Osborne help page that you get on booting CP/M. They crammed everything onto a single sided 100k disk. Now, do I try and centre that screen display… pretty sure you have to pull the screen out of the enclosure to do this. CP/M says hello! Well, actually it says ‘Hello from a working Osborne 1” in capitals because I have caps lock on for reasons.
December 16, 2025 at 12:15 PM
binarydinosaurs.co.uk
#osborneJapes status.

Machine boots. Keyboard toast (as usual). SSDD disk written but boot fails, the original cable has a hole in pin 34 which on this spec is a signal called LATE. With that cable both floppies just seek constantly. New cable fitted and the drive just spins. Puzzlement.
Overall view of the caseless Osborne showing the tiny 5” CRT next to a pair of 5.25” floppy drives. Keyboard is borrowed from my Osborne Exec because on the original keyboard the Return key doesn’t work.
December 15, 2025 at 7:34 PM
binarydinosaurs.co.uk
#holidayOsborneJapes
Yes, I’m on holiday this week so why not start the way I mean to go on - pulling Osborne RAM chips. So far 8 tested and 3 dead. This doesn’t bode well for the other 24.
All 32 ITT 4116 RAM chips on the Osborne 1 board with 1 already replaced and 2 more empty spaces that will soon have socketed chips in them. Also visible is the 33rd 4116 which acts like a gatekeeper for the others. That one is fine. Good ones are soldered back onto the board because I don’t have 32 sockets.
December 15, 2025 at 12:25 PM
binarydinosaurs.co.uk
#osborneJapes continue. Last night I pondered that the 6821 PIA that controls RAM addressing may be causing both machine death and those wild D4-7 scope traces.

Chip pulled and the machine death is identical as expected, but those bus traces are still the same. Bah.
One removed 6821 sitting pretty on the board it was removed from.
December 13, 2025 at 11:48 AM
binarydinosaurs.co.uk
FLEEE! It’s the Osborne Monster!

Pretty sure I saw this in a dream last night.
Thermal image of the Osborne 1 board with a logic analyser clip on the CPU while i try and decode what’s going on in that little machine. Thermal camera is a lot more preferable for finding dead chips than the ‘manual FLIR’ method I used to use which resulted in many a singed finger and burny smell.
December 12, 2025 at 7:05 PM
binarydinosaurs.co.uk
I’m not entirely sure WHAT’s going on here. Looks a bit wild.

Say hello to D4 on the Osborne. Normally at this point I’d pull every chip it touches but that includes a pair of 6821 PIA 40 pin DIPs that I don’t have spares of. Yet. They’re notorious for going bad over time.

Also checked RAM.
An oscilloscope trace of D4, it’s not supposed to be that… weird.
December 12, 2025 at 6:17 PM
binarydinosaurs.co.uk
#osborneJapes It’s always the last tantrum you find on the board innit 🙄

Now we have stable power and I get a floppy click on power up. Result.

Do I have Osborne disks? Hells no. Not yet anyway. I do have a Greaseweazle though.

Hm, wonder if there’s any other boot disks with my Osborne Exec…
A rogue 15uF 10v tantalum capacitor that’s failed dead short. Yes I KNOW they look like jelly bellies but you don’t want one of these in your mouth when they go off.
December 10, 2025 at 6:50 PM
binarydinosaurs.co.uk
Osborne restoration day 1.

Hello my old friend, we meet again.

This is my nemesis, the Astec AC8151, beloved of system builders in the early 80s and very disliked by me in the 2010s 😆

All original caps too, so C9 (startup) is probs dead. First task though is to clean up the ex-RIFA.
The Astec AC8151. The usual RIFA smokebombs have been removed after one of them did explode as is visible by the mess next to the bridge rectifier to the left of the orange capacitor lower left. It needs to be cleaned up and new caps fitted. Also visible is the startup capacitor C9, just where the blue wires cross on the left. It’s usually a 220uF 16v cap and it’s usually dead which is why the PSU won’t come up.
December 8, 2025 at 7:17 PM