Search found 302 matches

by kmurta
Sun Mar 24, 2024 10:20 pm
Forum: Software
Topic: Forth Hints & Tips: Kaleidoscope
Replies: 11
Views: 765

Forth Hints & Tips: Truchet Quarter-circles tiles

Forth variant: TF79 (Requires the HGR extension)

Reference: https://en.wikipedia.org/wiki/Truchet_t ... er-circles

truchet.png
click to open
click to open

Note how screen 7 was used to load the program, since screens 1 to 6 are occupied by the high-resolution screen.
by kmurta
Wed Mar 20, 2024 1:41 am
Forum: GAMES
Topic: Snake Game - a game written in Forth
Replies: 3
Views: 328

Snake Game - Some optimizations

We saw previously that the snake becomes slower as it grows and the main reason for this is the DRAW-SNAKE routine: : DRAW-SNAKE LENGTH @ 0 DO I SNAKE-X C@ I SNAKE-Y C@ DRAW-BLACK LOOP LENGTH @ SNAKE-X C@ LENGTH @ SNAKE-Y C@ DRAW-WHITE ; Note that the snake is completely redrawed for each cycle, whi...
by kmurta
Tue Mar 19, 2024 12:12 pm
Forum: Development
Topic: Enhanced ARX True High Resolution Display Driver
Replies: 13
Views: 635

Re: Enhanced ARX True High Resolution Display Driver

So it sounds like on the UDG4ZXpand there is a physical jumper that must be set to enable 128 character mode. For Chroma 81, the RAM in the 8K-16K region (if enabled) is always capable of 128 character mode and it is bit 0 of the I register that determines whether to use 64 or 128 character mode. I...
by kmurta
Mon Mar 18, 2024 7:31 pm
Forum: Development
Topic: JOY81 - Programmable Joystick Interface for ZX81
Replies: 102
Views: 61551

Re: JOY81 - Programmable Joystick Interface for ZX81

msknight wrote: Mon Mar 18, 2024 4:21 pm Anyone know how to make/get the piggyback board please?
Here: viewtopic.php?p=49047#p49047
by kmurta
Mon Mar 18, 2024 4:25 pm
Forum: Development
Topic: Enhanced ARX True High Resolution Display Driver
Replies: 13
Views: 635

Re: Enhanced ARX True High Resolution Display Driver

I recall there was an UDG4ZXpand board (which I think Andy created also but correct me if I am wrong). I'm wondering if this will make the 8K-16K RAM provide by the ZXpand ARX compatible. Does anyone know? Yes, all external RAM connected to UDG4ZXPAND is capable of providing UDG xor WRX. Selection ...
by kmurta
Mon Mar 18, 2024 3:09 pm
Forum: Development
Topic: Enhanced ARX True High Resolution Display Driver
Replies: 13
Views: 635

Re: Enhanced ARX True High Resolution Display Driver

Excellent! ARX is a great option to use with Brazilian TKs clones, which do not tolerate WRX very well. As soon as I have time I will test it on my TK85. The ARX display technique devised by Andy Rea in 2006 is fascinating in that it could have given true high resolution graphics back in the day usi...
by kmurta
Sun Mar 17, 2024 3:17 am
Forum: Development
Topic: werewolf for the zx81 16k
Replies: 11
Views: 780

Re: werewolf for the zx81 16k

KEY is missing but INKEY isn't, so you can define KEY as

: KEY BEGIN INKEY ?DUP UNTIL ;

Take a look at chapter 16 of the manual, it will help a lot!
by kmurta
Sat Mar 16, 2024 10:59 pm
Forum: Development
Topic: JOY81 - Programmable Joystick Interface for ZX81
Replies: 102
Views: 61551

Re: JOY81 - Programmable Joystick Interface for ZX81

Remembering that you must provide the piggyback connector, although I think this other solution is better: https://www.zx81keyboardadventure.com/2 ... iGfnhStNoE
by kmurta
Sat Mar 16, 2024 10:43 pm
Forum: GAMES
Topic: Snake Game - a game written in Forth
Replies: 3
Views: 328

Snake Game - a game written in Forth

There is this good tutorial on the Forth language which presents at the end a small game written in Forth, Snake!. We will see that the task of transcribing it for the Forth-79 is very simple, even though the game was written to run on modern PCs. Before proceeding, I suggest you read the original a...
by kmurta
Sat Mar 16, 2024 9:50 pm
Forum: Development
Topic: JOY81 - Programmable Joystick Interface for ZX81
Replies: 102
Views: 61551

Re: JOY81 - Programmable Joystick Interface for ZX81

I know that there are still people interested in obtaining a JOY81, but unfortunately at the moment I am unable to start producing a new batch. I still have some PCBs left but unfortunately the cost to send them outside of Brazil is excessive (more than 30GBP), so I will make the files available her...