Some notes from The Spectrum Show

Some notes I made watching The Spectrum Show.

New games:

Antiquity Jones 2012 Paul Jenksinson

More Tea Vicar 2012 Cronosoft

Future Looter 2011 Timmy

Alter Ego 2011 RetroSouls

Genesis: Dawn of a new day 2010 RetroWorks

Interesting old games:

Glug Glug 1984 CRL

Ninja Hamster 1987 CRL

Worth remembering:

Arcade Pac-Man emulator for ZX Spectrum

Arcade game designer 2008 Chronosoft

 

Recommended retro ZX Spectrum related Youtube channel

If you are interested in retro computing, especially Sinclair ZX Spectrum computing, I highly recommend Paul Jenkinson The Spectrum Show if you haven’t found it yet.

It is very well made series with a nice structure: news of that era, software comparison, game reviews, new software reviews etc. Highly recommend.

 

Making ZX Spectrum edge connector

If You are a little bit into retro computing and would like to experiment with ZX Spectrum computer outputs or make some extension board for it for some prototyping, then you need ZX Spectrum edge connector ( if we talk about original ZX Spectrums ). It is easy to make one by Yourself, just buy some regular 28x2P 56P 2.54mm 0.1″ edge connectors on ebay and saw off both ends of it so they could be used for ZX Spectrum, done.

Cleaning and repairing ZX Spectrum +3

Got a somewhat cheap ZX Spectrum +3 to my collection. It was marked as untested in eBay ( they usually are ), but I took the risk and bought as the price was ok.  On first test it powered up, the floppy disk was providing sound, TV could be tuned and startup menu appeared. First noticed that some of the keys ( lower part ) were not working. My guess would be that membrane will have to be replaced but anyway, disassembly will show. And it showed. As it more or less was obvious from outside inspection – inside was dirty as hell.

Then, after some cleaning:

I have no CF-2 floppy diskettes to test, so decided to plug in a tape recorder and test some software from and audio cassettes and the i noticed.. that audio jack was missing! It seems that it was just cut away! Found similar one in one my spare parts box and soldered that in.

Also decided that as soldering iron is hot anyway why I would not just make a quick composite mod in the UHF box (using a capacitor). Did that, reassembled it, plugged it in and… yeah – no video.

So, I have undone composite mod, restored everything to original condition and started making RGB to SCART cable for it.

Interface 1bis file not found error

Purchased Interface 1 bis for the ZX Spectrum. 
There are plenty information about it and installing and preparing SD card on manufacturers site https://sites.google.com/site/interface1bis/ 
But I have encountered a problem – could not start it and was allways getting “file not found” error.
Did all steps described in troubleshooting video https://www.youtube.com/watch?v=QYHhWQyVWAU 
Loaded OpSys from PC using LOAD command, program loads OK. But when I do NEW and then RUN I get “file not found” error. 
Solution I found was that I had to repeat all prepare SD card steps, but additionally had to add comparability with Windows 8 (and run as administrator off course) option (I was running Windows 10) to LDCSetup.exe and later to the ‘Prepare new card’ utility.

So, In short – add Windows 8 compatibility to Interface 1 bis utilities.

Some links for ZX Assemlby programming

Making games in ZX Spectrum assembly book ( russian lang.):
http://zxpress.ru/book.php?id=2

How to write ZX Spectrum games tutorial in English:
https://chuntey.wordpress.com/2012/12/18/how-to-write-zx-spectrum-games-chapter-1/

Spectrum ROM routines:
http://skoolkit.ca/disassemblies/rom/asm/2852.html

Z80 instruction set:
http://clrhome.org/table/

Group in FB dedicated for Z80 assembly programming:
https://www.facebook.com/groups/z80asm/

WOS forum link:
http://www.worldofspectrum.org/forums/categories/assembler

Another forum (ru):
http://zx-pk.ru/forums/14-programmirovanie.html

Some more books (ru):
http://vtrdos.ru/

Repairing ZX Spectrum Kempston joystick

As recently I started tinkering with ZX Spectrum hardware, tested one old joystick I had. Up and right positions did not work during the games. Tested port reading with one simple program:

10 LET x=IN 31
20 PRINT X
30 GOTO 10

There was no reading in up and right position.
I took apart joystick case and tested connection between PCB and plug – there was no connection for up and right wires.

So, just took now DB9 female connector and soldered it instead of an old one that I have just cut away.

 

Fixing ZX Spectrum+ 48K (s/n S01-135100) video problems

So, this ZX spectrum was alive, but during testing with some games (for example game “Breakthrough”), I noticed strange video glitch in upper screen part:

My guess was it is not video RAM related, but probably RF module fault. First decided to change all electrolytic caps on the board and see if it helps – it did not. Picture was the same.

Then decided to check RF module – remove it and re solder all joints.

After putting it back I did a check with the same game. It helped a bit, but still I was not happy with the result. White line disappeared, but it seemed like upper part was washed away a bit:

And then it came to my mind a thought about why the hell I am using this RF module at all. I could just do a composite mod and that would definitely would solve all RF related video problems.

Composite mod as it is called, is just disconnecting power and signal wires that go from RF module – means disconnecting RF module. Then, in the RF module itself, disconnecting resistor from video output connector. And finally, connecting video output from board to video output connector in RF module using 100uF 10v electrolytic capacitor ( negative to the board, positive to video output ).

That`s it, did those changes, connected to TV`s composite video input and got clear picture without any RF glitches.

( Making this change i did not cut any wires etc. Just desoldered and moved away. Idea is that I could easily return RF module functionality i.e. undo this mod. )