Search found 1610 matches
- Mon Sep 25, 2023 10:20 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
Re: Oh no! Not another ULA.
Sorry its been a while... not really sure if its worth pursuing 4X speed any more. 4X speed withg ZXpand ?? probably not... I can't get it stable at all. 4x speed is possible without modifying the main board, we now have 6 wires, 5 you already know about ( extra address lines) the extra wire is conn...
- Sat Sep 16, 2023 6:24 pm
- Forum: Development
- Topic: Comparing a (1 byte) variable with a number for equal
- Replies: 11
- Views: 7307
Re: Comparing a (1 byte) variable with a number for equal
If it were me i would use 0 or 1 ( single bit rather than 2 separate bits) and change the code to something like :- ; variables i_frame .byte 1 ; starting frame main_loop: ; check frame LD A,(i_frame) ; get current frame AND 1 ; bit 0 set ? JP NZ,frame_1_do ; if so... ; ...if not continue here ; do ...
- Sat Sep 16, 2023 5:52 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
Re: Oh no! Not another ULA.
getting somewhere now...
inverse video, Check
inverse border, Check
Double Speed, Check
Quadruple Speed.... Wait what... anyway... CHECK
https://www.youtube.com/watch?v=qy5egYyYEVo
just the good ole POKE ..
Andy
inverse video, Check
inverse border, Check
Double Speed, Check
Quadruple Speed.... Wait what... anyway... CHECK
https://www.youtube.com/watch?v=qy5egYyYEVo
just the good ole POKE ..
Andy
- Mon Sep 11, 2023 8:26 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
Re: Oh no! Not another ULA.
Been a few days... still here... nothing new has happend... apart from maybe a few more grey hairs....
- Tue Sep 05, 2023 10:52 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
Re: Oh no! Not another ULA.
that's rather interesting, however I don't think I want to modify my memotech keyboard just yet...
right this minute I'm having a bit of fun trying various ideas
regards andy
right this minute I'm having a bit of fun trying various ideas
regards andy
- Tue Sep 05, 2023 3:05 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
Re: Oh no! Not another ULA.
haven't really tried it on a standard keyboard.. so definitely the memotech at the moment. oh the 20Mhz zx81 had a completely split address and data bus all done inside the cold, so no resistor blocking and digging signal improving signal integrity massivly not to mention improving the amount of swi...
- Mon Sep 04, 2023 9:59 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
Re: Oh no! Not another ULA.
Well i didn't expect that, keyboard reads are screwed up at 13Mhz !!!
- Mon Sep 04, 2023 5:16 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
Re: Oh no! Not another ULA.
@paul... re write protect rom.. so my idea then is ~RAMcs remains untouched... you add ram its your problem to solve addressing ect. ~ROMCS to be selectable option a) as is.. OR option b) the following conditions have to be met. 1) address =< $1FFF. 2) Mreq ( or stretched Mreq ) has to be low. 3) @W...
- Mon Sep 04, 2023 2:57 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
- Mon Sep 04, 2023 2:10 pm
- Forum: Development
- Topic: Oh no! Not another ULA.
- Replies: 79
- Views: 99615
Re: Oh no! Not another ULA.
About blinkenlight pins: I guess both oscillator pins are unused :?: About BigBang: which content is at address 1001? 255? the orioginaal OSC pin ( pin 35 ) is coonnected.. its function is to use the 18K resistor on the zx81 as a pulldown. it could easily be left unconnected and a pull down placed ...