Monday, December 29, 2008
Sinclair C5 coast run
I've not had time to watch all of this video but here it is for your delight and delectation
Thursday, December 25, 2008
Redefining the ZX Spectrum character set
This was something I always wanted to do as a kid but could never get it to work. Thought I'd have a bash tonight and it was pretty easy after realising two key facts:
(1) The CHARS system variable needs the low byte of the address of the new character stored before the high byte
(2) BUT for some reason, the value of CHARS needs to be 256 less than the start of the new character set.
Here is a screenshot of the BASIC program I knocked up as a simple test of a new 'A' character.
After a break, I remembered a game I really liked in about 1985 called Bored of the Rings which had a good font. I had a think, and came up with this plan:
- Load Bored of the Rings into Fuse on my Mac
- Open the Memory Browser and look at the contents of 23606 and 23607 which together contained 0xBE68. Adding 256 to this gave a memory location of 49000 for the start of the new character set
- I exported using File / Export Binary Data from location 49000 and length 768
- I then loaded my test program from earlier, did File / Import to load the binary data back to 49000 and then did POKE 23606,104 and POKE 23607, 190 and lo:
New Spectrum game: ALBATROSSITY
Knew we could count on him to release something to brighten an otherwise dull day - you can download Albatrossity from Jonathan Cauldwell's web site.
Wednesday, December 24, 2008
I've single-handedly saved Cronosoft!
Many thanks for the order of games - I've had so many orders since posting on WOS, it looks like we'll be around for a while yet!
He's sent me the emulator versions of the titles while I wait for the tapes. splATTR looks great under ZXSpin on my PC/Windows but resets as soon as I load it under Fuse/Mac OS x :-(
Tuesday, December 23, 2008
RST 16 modifies the accumulator...
Aargh - it's taken me a depressing amount of time to realise that the RST16 call to print the contents of the accumulator on the ZX Spectrum has the side effect of modifying the contents of the accumulator. That'll explain why I was getting an "INVALID INK COLOUR" error message in BASIC...
Click on the images for larger versions - they're very exciting...
I've been checking out the Cronosoft forum recently and thinking about how quiet it has been.
Today, I had a look to see if I could find a more active forum, since comp.sys.sinclair seemed a bit dull (!) and saw a thread on the World of Spectrum forum that made me dash off that order for Platform Game Designer (PGD), Shoot 'Em Up Designer (SEUD) and splattr that I've been meaning to place for a while.
Monday, December 22, 2008
Z80 machine code
- Installing jEdit on my Mac - started with Eclipse but got bored of trying to get the Z80 plug-in I'd found to work
- Installing the pasmo compiler
- Playing with Jonathan Cauldwell's 1K Kilopede game
Sunday, December 21, 2008
Latest order for the C5
Wednesday, December 17, 2008
James McKay's Teenage Programming Atrocities
Sunday, December 14, 2008
Lemmings for the DS
I used to play Lemmings on the PC when I was at university (more interesting than Genetic Algorithms and Z!). I was Lemmings playing on my newly-modified composite video ZX Spectrum earlier today when I thought of searching for a version for the DS.
I found this freeware version which seems pretty good so far although I have only played the first level.
Saturday, December 13, 2008
Composite video for ZX Spectrum
I applied this modification to my ZX Spectrum and while the display is much better, it seems as though the video signal is picking up some noise from the clock as there is a slight shimmering. It is more noticeable when running ZEUS (white text on a blue background) than other combinations of colours such as black ink on white paper.