Geoff Wearmouth
warmtoffee.bsky.social
Geoff Wearmouth
@warmtoffee.bsky.social
55 followers 21 following 67 posts
Press plastic for a living but love the touch of rubber. Assembler of Gosh Wonderful and Looking Glass ZX Spectrum ROMs.
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In both the ZX81 and ZX Spectrum the division routine misses a shift and the 34th bit is lost.
As Dr. Frank O’Hara explained a jump to DIV-34TH must be made and not to DIV-START. After division the mantissa is not normalised. Normalisation pulls in the 33rd unset bit from A and bit 34 moves to 33.
Here is the Z80 source code from my ZX Spectrum ZEUS assembler.
And on Page 44, yours truly with a short ZX Spectrum type-in “Spherical Objects”. No image or Z80 source code but that is fixed now.
Reposted by Geoff Wearmouth
One of the most difficult BBC Micro books to obtain. Is there anyone out there that has a copy? I managed to get an ex-library copy that was re-bound. Curious to know how many are actually around. It was withdrawn from sale for legal reasons - it contained an annotated disassembly of BBC BASIC.
This is the most exciting ZX81 BASIC program ever. It runs on any Sinclair ZX81 model - TS1000 etc. It compares the upcoming LG81 ROM with the host ZX81 ROM.
This BASIC program should be downloadable soon but if you want to see how bad your ZX81 is get typing. Developed on iOS ZX81 by Kevin Palser.
A nice Page 179 on BIN, ATTR and pure colours.
Amstrad messed up that text in all their manuals but 30 years later in 2014 Steve’s penguin had the last word on BIN 010 (It’s 2 not 4).
This is the most revealing ZX Spectrum BASIC program ever. It runs on any Sinclair model - Spectrum, TS2068, or any clone.
It compares the error-free Looking Glass ROM v1.08 against the host ZX ROM. It should be downloadable by the weekend but if you want to see how bad it your Speccy is get typing.
It’s all happening in 1982. Dr. Ian Logan reveals three ZX Spectrum bugs on the letters page and on Page 19 there is a competition to win a newly launched Jupiter Ace.
Remember in the 1980s when Sinclair and Amstrad dropped the price of The ZX Spectrum. Well RGL have continued the tradition and you can buy The Spectrum for £84.99 - 5% off. Just download the Looking Glass ROM V1.08 from Spectrum Computing or speccy4ever

www.smythstoys.com/uk/en-gb/gam...
speccy4ever.com
I have seen a YouTube video of Federico Faggin referring to the processor inside as the “Zee-Eighty”. He cleverly designed it so no objections there.
If, as I expect, those ZX Spectrum machines have sold out then you can go to Amazon Prime,
smythstoys.com , Argos etc. and have a much more exciting model for £89.99 😊. With my LG18 v1.08 ROM installed it will run all 48K software. You can get it all on one SD Card too.
Isometric ZX Spectrum game by Chris Smith who designed my “The Spectrum” machine and has been a leading light on the Spectrum scene for over thirty years. Author of the book about “The ZX Spectrum ULA”.
That is a great issue with Nigel Searle explaining that the QL might have a Z80 co-processor and, after his Beijing visit, ZX Spectrums will be assembled there.
Best bit is this letter from Paul Ockenden whose type-in reveals all the ZX Spectrum Scrabble words.
That is my weekend taken care of.
My virtual computer written in ZX Spectrum BASIC highlights some more errors in the original 1982 ZX Spectrum. My latest ROM is error free.
Inspired by a S. McCarthy ZX Spectrum f.p. program my Virtual Computer has a flexible exponent and mantissa and will convert a decimal number to perfect binary.
The only data from the ZX Spectrum is the bright yellow exponent and mantissa. Wrong digits will be highlighted in red.
Back in 2014 Dr. Steve Vickers made some lecture slides available on his University website. I used his decimal to binary conversion routines to expand on a floating point display program I had typed in. This created a virtual computer with correct exponent and mantissa to test my ZX Spectrum ROMs.
I uploaded it to spectrum computing

spectrumcomputing.co.uk/entry/40367/...

Where Thomas had reserved a place for the ZX Spectrum program.
I could not get it to repeat the exact
Results but I intend to return to it.
It inspired me.
Floating Point Numbers - Spectrum Computing
Floating Point Numbers for ZX-Spectrum 48K (?)
spectrumcomputing.co.uk
Reposted by Geoff Wearmouth
The very brief mention of MGT's ZX Spectrum Emulator in the #SAMCoupe user guide here, being called "a special program". For the initial emulator MGT had to create a compatible #ZXSpectrum ROM from scratch, as the actual ZX ROM's copyright was held by Amstrad. The compatible ROM wasn't fully...
The Looking Glass ROM V1.08 for the 48K ZX Spectrum is now available for download with documentation.

speccy4ever.speccy.org/_CMS.htm

This is the most accurate ROM ever available for the ZX Spectrum and is the equal to Microsoft Binary Format 9-digit BASIC. Say goodbye to dodgy figures.
It’s all happening in 1982. The ZX Spectrum is launched in April. By September the Jupiter Ace makes its debut.
Two pages of Colin’s paperback give some love for my favourite ZX Spectrum emulator, the PC version of Spectaculator by Jonathan Needle. It is so accurate with the ZX Microdrives and the ZX Printer. Well worth the small payment for so many models emulated.