Robert Morrison

I am on my holidays.

Animated GIF. Image shows a wall mounted hotel room TV displaying the loading screen of Future Knight on ZX Spectrum (the computer is on the desk loading the game from cassette tape).

I’m working on my (second ever!) ROM hack this weekend and a random glitch has given me an idea…

A screenshot from Jetpac on the ZX Spectrum. The rocket ship graphics have corrupted and it has turned into an improbable tower of jumbled spaceship parts. Matchbox “Con-nect-ables” branded toy vehicles in a retail hang-card blister pack. The toys are segmented so you can recombine them in interesting ways such as adding wings to a car, and so on.

Work in progress! (This photo didn’t attach to the previous post for some reason). I’d had the thing open years ago to service the belt or something but the old brittle wires gave way and it took some effort to deduce what goes where! It languished in the garage for ages; being raided for parts a couple of times, but I decided to give it another go last night. I couldn’t find a schematic for the whole unit, but the data sheet for the LA4160 amplifier IC was very helpful.

Photograph of a disassembled shoebox style cassette recorder. There is a cassette in the exposed mechanism and many wires all over the place. I’ve connected a logic probe for some reason. It’s playing Matchbox Twenty but you can’t hear it because this is a photograph.

Fixed it! I had to improvise an output socket—I harvested the original one when I thought this player was beyond repair, but this was my childhood Spectrum cassette recorder so I made the effort to fix it. #HiFi #ZXSpectrum

Cassette recorder with an improvised earphone socket made from a small breadboard and some jumper wires. There’s a resistor for decoration but it’s not serving any electronic purpose. The breadboard has been optimistically labelled “HI-FI”. Overhead photo of the cassette recorder showing lots of patina from decades of wear and tear. It’s dusty, scratched and worn with a small faceplate around the tape counter missing. A red cassette tape can be seen through the deck window. The label reads: SKATE OR DIE; DOUBLE DECKER TAPES. A modified ZX Spectrum with a white key mat and a shiny RTS sticker (see RoseTintedSpectrum on YouTube dot com).

Midnight maths club

Tonight we’re learning (or really just enjoying looking-at) bifurcation diagrams generated by Feigenbaum constants (…and very slowly plotted on a ZX Spectrum!)

Photograph of a CRT telly displaying a Feigenbaum constant bifurcation diagram generated by a ZX Spectrum Photograph of a CRT telly showing a BASIC listing of the program that generated the diagram in the other picture. The program is by Ettrick Thomson.

I had a great time at the Acorn Computers User Group meet-up last night in Falkirk. I was notionally representing SAM Coupé, but I spent almost the entire time learning about Elks, Masters, and RISC OS machines (and much more!) More pics at Spectrum Computing forum.

📷 Tosk / Retro Rendezvous

SAM Coupé computer with a few expansion cards plugged in, connected to an LCD television. On the screen is a blue and green horizon. Disks (and a spare SAM Drive) are scattered around.

“The marvellous thing about a singing horse is not that it sings well but that it can sing at all. To accomplish speech synthesis on a Spectrum with no additional hardware is a marvel of a similar order”.

Spectrum Computing issue 01

Screenshot of a CRT television set. Text on screen reads: The marvellous thing about a singing horse is not that it sings well but that it can sing at all. To accomplish speech synthesis on a Spectrum with no additional hardware is a marvel of a similar order. Spectrum Computing title screen. May/June issue (c) 1983

ZX Spectrum PlusD (clone) disk interface. The last of the parts arrived today so I blew the EPROM and programmed the GALs. And it worked!

An almost fully populated PlusD interface circuit board with three ICs missing. Using a GUI on an ancient Windows laptop to operate a USB programmer (a cheap TL-866-II clone) to program a GAL. Picture shows the programmer device sitting on the open laptop with the GUI on screen. A slim 20 pin IC is inserted in the programmer, and the device has a brightly glowing red LED. PlusD interface connected to a 48K ZX Spectrum. Floppy disks, drives and ribbon cables are strewn around. Yellow and red LEDs are brightly glowing on the PlusD. It has no casing, so the circuit board is visible.

Tell you what, going back to 1206 SMT components after working with 0805 scale devices is like moving paving slabs around. (Strawberry Chuppa Chupp for scale)

Detail of a partially assembled circuit board. Small SMT components on millimetres in size have been soldered to the board. A strawberry Chuppa Chupp lolly has been put into the photograph to give a sense of scale.

Well. Time to learn how to blow a GAL. 👨🏻‍🏭

Two DIP IC chips in plastic storage tubes, and several transistors in a small plastic bag.

I thought something was wrong with my PlusD disk interface so I took it apart for inspection… and who would’ve guessed it, the problem was just a duff floppy disk! 😩🥴😛💾💾💾

PlusDLite disk interface without its casing, plugged into a ZX Spectrum +2A. A couple of disks are scattered around with labels “Zeus Assembler” and Beta DOS”.

It’s never given me any trouble to be honest, it’s easily one of my favourite Spectrum accessories.

(I’ve no idea why I didn’t immediately suspect the well-used second-hand disk I got in a job lot from eBay!)

I quite often replay the original Tomb Raider around Christmas time, but I really associate it with the new year. Anyway this year I was looking up some of the secrets I’ve never found, and discovered a bug(?) in the PAL version: the third secret in The Cistern is inaccessible!

Screenshot of PAL version of Tomb Raider, the Cistern level. Lara Croft is standing on a stone balcony looking at a disguised moveable block that’s hiding a secret area. The texture of the block is slightly different to the surrounding walls. Screenshot of NTSC version of Tomb Raider, the Cistern level. Lara Croft is standing on a stone balcony looking at a disguised moveable block that’s hiding a secret area. Unlike the PAL version the texture of the block is the same as the surrounding walls so it’s harder to find. (Note the screen borders as this is running on my 50Hz PAL Saturn!) Screenshot of NTSC version of Tomb Raider, the Cistern level. Lara Croft has moved the disguised moveable block revealing the secret area behind.

Well it might be the twelfth night but it’s not too late to post about my ADVANCED CHRISTMAS JUMPER SIMULATOR for ZX Spectrum. And do check out the rest of the latest W00t! tapemag for loads more laughs and games.

ZX Spectrum screenshot. Image shows two people wearing ugly Christmas jumpers. The text reads Advanced Christmas Jumper Simulator.

Moley Christmas, dudes. Cowabunga.

“Moley Christmas” game for ZX Spectrum on cassette tape being held by Leonardo (Teenage Mutant Ninja Turtles) action figure, standing in front of a ZX Spectrum. Fairy lights in the background.

ZX Spectrum Next

It’s important to stay organised in the hectic modern world of Information Technology.

A small red notebook with a Tip-ex’d label that now reads “Computer tapes log book”. In the margin are ball-point pen doodles, it appears to read “1992” First page of a notebook, reads “Saracen Paint piccys” and lists the tape positions of the picture-files named “Ferrari” and “Duck”. Underneath is written “Hungry Horrace Works on B side”

Sunday: upgrading an already-modified (but still with with notoriously bad and unbalanced sound) ZX Spectrum +3 with a stereo modification from ByteDelight. It attaches directly to the AY-3-8912 (separating out the channels) and taps into the gate-array to pick up the classic beeper sound as well.

Close up photo of a back-lit printed circuit board. In the centre of the image a white adapter-board with very small components has been attached on top of a large microchip. Various wires are coming off the adaptor and out of sight. Television shows white text on black that reads “a short demo about jetpacks”. Below the tv, a weird-looking ZX Spectrum glows green.

Saturday: time to install a Word Processor onto Hard Disc Drive. (Not to mention the 70,000 word dictionary and a collection of “several” typefaces). #Tasword #zxspectrum #plus3e #yolo

Television showing text, listing the names of files. Also pictured: customised ZX Spectrum +3, a 3-inch floppy disk drive and the large clamshell box for “Tasword Plus Three”.

Midnight hackers club. Who wants to write a text scrolly? #ZXSpectrum #specasm #z80

Photograph of a TV screen showing a syntax-coloured machine-language program listing.

Piña colada / collida detecta (if you’ll indulge me one last #fomo toot xx) #Z80 #ASM

Piña colada in a tall glass with what looks like the world’s largest cocktail umbrella. The blue sea glints in the background. Screenshot of annotated Z80 assembly code that’s designed to detect collisions between game objects, “bullet” and “bug”. Some smug guy can be seen reflected in the glass surface of the computer screen. He might be holding a piña colada.

As cool as it’s possible to be in this heat. #SAMCoupé #ZXSpectrum #poolside

Literature by a swimming pool. “SAM Revival” magazine by Quazar, and “Super Charge Your Spectrum” by David Webb. Palm trees and steep mountains are in the background.

Keep cool at the pool. 😎 📚 ⛱️ #zxspectrum #asm #z80

Paperback book in the sunshine by a swimming pool. The title is Advanced Spectrum Machine Language, by David Web.

I’m travelling for work today so I’ve brought the laptop, an Amstrad NC100. For on-the-go connectivity all you need is an RC2014 connected via RS232 at 9600 baud.

P.s. don’t zoom in, I’m doing important Business Work™ not playing Zork.

Amstrad NC100 connected to RC2014 via RS232

This week I’ve been wrestling with SAM networking again! SAVEing works perfectly (Net and Tape format are almost the same so it’s easy to coerce the saved bytes into a .tap image). On the other hand bytes are being dropped on the way back; I’m not sure why. #SamCoupé #MIDI

Television, RC2014 on top, SAM Coupé to the side. Screen shows BASIC listing. Closeup of TV screen. Three columns of information: decimal numbers, hexadecimal numbers and ASCII text Handwritten hexadecimal numbers on a lined notepad. The notepad is on top of SAM Coupé SAM Coupé display showing the text “Code: NOTICE” implying it’s (trying to) load a code block.

Hmm. This feels like homework.

Right angled triangle sketched on feint ruled notepaper. The drawing is annotated with arcane symbols whose meanings have been lost to us, but suggest a high-school level understanding of trigonometry (maybe). Anyway a frog is firing a projectile up at an angle towards a fly, so this is probably about working out that trajectory.