Sinclair ZX80 / ZX81 / Z88 Forums

Andy Rea wrote:try this one, it;s hacked to increase the delay when testing for ZXpand

So how long a delay is required then? My original code had 20 Tstates worth - how much did you use?

Hi Bobs,

After some talk with SirMorris, and a little experimentation, i found that anything over 40 cycles worked on my machine with the latest firmware / rom. After doing a byte search (luckily your code is the same as Sirmorris example) i was able to find the test sequence in my favorite binary eidtor, and changed the 5 nops for :-

push af
call $002f ;jumps to a ret instruction
pop af

which if i'm not mistaken takes 48 cycles.

you could of course use any code that leaves registers ect intact...

Regards Andy

It looks like the heartbeat code has moved and now takes longer to respond than it used to :¬<

I'll have to update the examples.

C

Andy Rea wrote:Hi Bobs,

After some talk with SirMorris, and a little experimentation, i found that anything over 40 cycles worked on my machine with the latest firmware / rom. After doing a byte search (luckily your code is the same as Sirmorris example) i was able to find the test sequence in my favorite binary eidtor, and changed the 5 nops for :-

push af
call $002f ;jumps to a ret instruction
pop af

which if i'm not mistaken takes 48 cycles.

you could of course use any code that leaves registers ect intact...

Regards Andy

Thanks for the info. I'll make sure I update the build to include at least 48Tstates, and also use that for any future games. (In the future I'll probably submit the request the frame before or similar - it's just in this case the joystick support was added as an afterthought)

Ermm - I tried it at the Spectrum is 30 show yesterday where I had been demo'ing programs all day, and I couldn't get it to respond to the joystick...

RWAP wrote:Ermm - I tried it at the Spectrum is 30 show yesterday

Do You have any photos from the party?

I was too busy to take photos - there will be lots on world of Spectrum !

It would be good to add joystick support to the ZX80 flicker free games from Paul Farrow -

http://www.fruitcake.plus.com/Sinclair/ ... hanism.htm

RWAP wrote:It would be good to add joystick support to the ZX80 flicker free games from Paul Farrow -
http://www.fruitcake.plus.com/Sinclair/ ... hanism.htm

Kong http://www.fruitcake.plus.com/Sinclair/ ... 0_Kong.htm has Kempston joystick support.

The game can be played using either the cursor keys (5 for left, 6 for down, 7 for up and 8 for right, 0 for jump), Sinclair joystick/keys (6 for left, 7 for right, 8 for down, 9 for down, 0 for jump), or a Kempston joystick. Press key C to cycle through the control options.

And from ftp://ftp.worldofspectrum.org/pub/sincl ... erface.pdf

The interface fits onto the Spectrum’s edge connector at the rear of the computer.

The interface has a 23 way connector so it can be used behind the ZX printer if required.

I have a number of Kempston compatible joystick interfaces. The early ones mostly seem to be fitted with the ZX80/ZX81 size edge connector. I have tested the working ones and have found that they work okay on a Zeddy

Mark

Ah but they don't work with the ZXpand Joystick....