Geoff Wearmouth

Celebrating a million Timex computers from Dundee -models ZX80, ZX81 and ZX Spectrum. All had forty keys only.

Engraved with words “Caithness Glass” “TIMEX 1000000 COMPUTERS” “DEC 83”. In a beautiful, silk-lined case.

To celebrate a million Timex computers from Dundee Sinclair Research commissioned a limited edition Caithness Glass crystal paperweight in the form of a ZX Spectrum. Only this prototype model was made. I bought it from a Dundee antique shop.

ZX81 App for iOS by Kevin Palser

🙂

The Sinclair ZX80 Manual has all the right characters but not necessarily in the right order. 🙂
CHR$ 228 is “>”
CHR$ 229 is “<“

A photo of the TS2000 which never was.

The accompanying photo is interesting as that Spectrum never shipped. Instead the US got the TS2068 in silver with a cartridge port.

Implementing a clear room Z80 / ZX Spectrum emulator with Claude Code: antirez.com/news/160

Go Johnny Go!
Viz magazine started in 1979.

You know what goes well with pancakes?

Yes! A MicroBeast kit!

feersumbeasts.com

I am out there where nobody can hear me scream.

https://archive.org/stream/NH2021_Popular_Computing_Weekly_Issue870212.pdf#page/n03/mode/2up (2/2)

This is the Nine Tiles source code for the ZX Spectrum and the label for the first address is PLUGIN: ; HERE WHEN MACHINE IS TURNED ON

No. In fact Steve Vickers labelled the first instruction “PLUGIN:”.

YouTube video by LOAD ZX Spectrum LOAD ZX 40: "Inside the ZX Spectrum" - Steve Vickers

Steve Vickers interviewed about his time at Sinclair, saving ROM space on the ZX81 and the ZX Spectrum and the new venture the Jupiter Ace.
youtube.com/watch?v=kgWj...

Indeed Macca wrote a custom COPY routine in contended RAM as it is a 16K game. The screen can be copied by pressing ‘P’ on the ZX Spectrum but the output is dithered. Nothing wrong with the ZX Printer - the custom COPY routine is written in contended RAM so the ULA has precedence. #SNOW

The image shows a listing of a program in the ZX Spectrum manual which accepts a date and returns the day of the week. I featured these lovely programs on my old demon website crediting Steven as author. I was delighted by my only contact with Steven which credited his mathematician/programmer turned mezzo-soprano sister with authorship. It is based on a program demonstrated to the press in 1950 and again in 1952. James Hardy Wilkinson demonstrated the machine explaining that an improved model The Deuce was being built by English Electric.

These Daily Mirror cartoons were very informative and a journalist and photographer would visit a company, in this case NPL at Bushey House. High resolution photos were taken from which the artists drew the strip each day. The photographs were never published and could have been discarded but thankfully were archived and you can see them online. They provide some of the best views of this Turing designed computer and the legendary people behind it.

Here is one of my favourite pages - better than a blank. The first Example ZX Spectrum BASIC program in the Appendix which is written by the sister of Steven Vickers, Penny. Her mother and father wrote it for the Press demo of the Pilot Ace in 1950 and again for a visit by the Daily Mirror in 1952.

David Webb, Investor Who Took On Hong Kong Tycoons, Dies at 60

Sadly, David Webb MBE, author of Supercharge Your Spectrum and other ZX books and games died on Tuesday, 6th January.
His NYT, free to read, obituary is here

www.nytimes.com/2026/01/13/w...

David M. Webb MBE (1983, Mathematics)

It is with great sadness that we share the news of the death of Prideaux Fellow David M. Webb MBE (1983, Mathematics), who passed away yesterday.

David was a distinguished Exonian whose legacy will not be forgotten.

🔗 Read the Rector's tribute: https://ow.ly/hhMa50XWF52

#ExeterCollegeOxford

The image shows an assembler listing for a display function on the Sinclair QL or ZX Spectrum Next with a QL core. Also a BASIC loader if you can’t afford an assembler.

A handy function, by T.P. Mervyn, to display the exponent and mantissa of a six byte floating point number on a Sinclair QL machine (or core).

The fault appears with 10 INPUT #3; a$ (Missing hash) And prevents stream 1 being used in the standard ZX Spectrum. Steven Vickers states in the Pitman Pocket Guide that stream 0 is for INKEY$ and stream 1 for INPUT.

My 2003 correction in the listing for gw03.rom on the Wayback Machine. Swap the order in which the two routines are executed. Note that Dr. Logan has used DF-SZ instead of TV-FLAG.

I had to double check that bug in the middle as I normally press ENTER when an error occurs. One can indeed continue to input a$ as described. I fixed this in the 2003 Gosh Wonderful ZX Spectrum ROM to allow stream 1 to function by making the CLS_LOWER routine precede the stream selection.

The very capable 8K ROM which was demonstrated at the Earl’s Court Computer Show was to be withdrawn for rewrite to accept the ZX printer.

As it turned out the rushed rewrite introduced bugs into already tested valid code and several ZX81 ROM rewrites would be required.

Tim Hartnell reports that the 8K ROM that had been sent to America (Syntax Mag.) and Middlesbrough (Linsac books) was to be withdrawn and features, like RESTORE, pulled for the ZX Printer. I would love to know how it printed floating point fractions. Has anybody got a copy of this early 8K ROM ?

The image shows a clean scan of the inside of the front cover which shows the author as Hugo Davenport.

By Hugo Davenport who revealed that X_TEMP is a label in the Z80
source code. Page 108.

A Coca Cola advert on top of a skyscraper in the artwork for the ZX Spectrum Introduction booklet by John Harris.

Things go better with Coca Cola. ZX Spectrum artwork.

Since I started this thread I have found the ZX Spectrum source code on the Internet Archive. This is part of the LN routine. Steve used Clenshaw’s coefficients for SIN and ATN but his own for LN and EXP. This was written for the ZX81 of course. Would someone so gifted write the crass code that processes fractions? Worse still would they stick with it. Of course not.

Russian stamps to celebrate the 125th birthday of Pafnuty Chebyshev, who makes the ZX Spectrum so accurate in the hands of Charles Clenshaw and Steve Vickers.

It doesn’t add up. In 1946 Steve’s parents were headhunted to work for Alan Turing together with Jim Wilkinson and Charles Clenshaw.
For the ZX81/ZX Spectrum Steve calculated his own Chebyshev coefficients for the LN function. He could never write that crass fuzzy code and choose to stick with it.

I have fixed all three imperfections in my Looking Glass ZX Spectrum ROM. V1.08 So useful to enter the comma control by deleting the ink control code leaving chr$ 6. The magazine have got the third error wrong and the offending line is 10 INPUT #3; a$ I fixed this by calling CL_LOWER before selecting stream 1 at the start of INPUT which happily gets rid of the errant cursor. I had to check that to make sure. Ne ROM in the New Year.

The letters page has three letters about niggly ZX Spectrum bugs.
First is that screenful of characters which I fixed by having a special console input routine. Next the manual error that CLEAR does a RESTORE. Steven fixed that in the Pitman Guide but Sinclair/Amstrad printed it in every manual.

Happy New Year! ✨

Looking back at 2025 — a great year at SC:

• 25 new updates of ZXDB
• 8 major releases of new website features and fixes
• 2,200+ videos re-created from the lost RZXArchive YouTube channel

🚀 2026 - looking forward to service the ZX Spectrum community - and related machines 😘

Conditions in the Intel 8087 floating-point chip's microcode In the 1980s, if you wanted your computer to do floating-point calculations faster, you could buy the Intel 8087 floating-point coprocessor ...

Intel announced the 8087 floating-point chip in 1980. Now I have a blog post that explains a small part of the microcode in this chip.
www.righto.com/2025/12/8087...

Nothing to copy or learn from. A classic case of GIGO. Garbage In, Garbage Out. Never process fractional digits one at a time. A lot of the competition had 24 bit mantissas and it beats them but it inhibits collecting the 34th bit to round a 32 bit quotient . It will not work with fuzzy logic. #ulp

A letter from Adam Hart-Davis who is 84!this year and developed and produced many computer and science series. He asks for computing celebrities and also developers of extraordinary uses for a forthcoming program “Me and My Micro”.

A productive letter from Adam Hart-Davis who joined Yorkshire Television in 1977 and would produce “Me and My Micro” as a result of this letter.

A very short but intriguing listing worth study. By G Bottomley. Page 33

A short example output.

A clever ZX Spectrum routine on Page 33 by G Bottomley that uses logarithms to calculate how many hex numbers will appear in the conversion. The ROM PRINT_FP routine does something similar with decimals.

Change txt suffix to asm. The sc01 files are a whimsy and not worth looking at. The disassembler in u3.asm is by John Kerr of Glasgow and was serialized in Personal Computer World. The sg81 source code can be read on the web page. Have fun.

My demon site and email are long gone but most of the ZX Spectrum site is preserved on the Wayback Machine.
Download the ZX ROM Collection for the files listed.

web.archive.org/web/20150602...

Did you know that the first instruction in the ZX Spectrum ROM is DI - Disable Interrupts. Quite a dramatic entrance. The DI instruction was not used in the ZX80 and ZX81.
Here is my ZX80 assembly listing from 2002. I tried to use the Logan O’Hara labels when apt.

web.archive.org/web/20150501...

How to set your ZX Spectrum to 10:00 am. Make it pause for twenty minutes.