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ZXpand vs ZXPand+

Posted: Wed Jul 12, 2017 11:23 am
by Lardo Boffin
I have yet to find the money to buy a ZXpand+ and was wondering what the major differences were between the two? I can see some differences in the firmware, e.g. the addition of streaming etc. but beyond that wasn't too sure!

On the note of streaming etc. are those kinds of improvement based on the new hardware? Obviously that is a leading question - if not then will such improvments ever make it back to the original hardware?...

I have a ZXpand plus AY so currently have music and joystick control. :D


Re: ZXpand vs ZXPand+

Posted: Wed Jul 12, 2017 12:09 pm
by sirmorris
The main functional differences are that the + has built-in YM chip and it uses an upgraded micro-controller which gives extra firmware storage space and work RAM. The addition of the serial IO might be a draw to some, its potential for MIDI and WIFI are presently being assessed.

In terms of build, obsolete through hole chips have gone. The twin GALs have replaced by a single CPLD. The RAM chip has been replaced by a teeny wee SMD part. This (at least on paper) represents a fair reduction in power requirements, though to be honest I haven't measured :oops:

Overall the boards are very similar functionally, but the + benefits from a new 'ready' signal which obviates the need for chunky timing loops in the ROM and produces a modest speed increase as a bonus. The ROM still busy waits for a command to complete but can now respond a scant few microseconds after the result becomes available. A small win but it accumulates quickly.

Most of the changes are firmware oriented. The ROM is changed quite significantly, though all entry points to the standard ROM routines are unchanged from the ZXpand Classic version - compatibility was one of my highest priorities. The changes have centred around size reduction and allowed new code to be added to assist in the use of 'streaming' blocks of data quickly from the sd card.

Some features have already been back-ported to the classic, namely the serial LOAD functionality and faster data transfer potential that I first developed for Dragon's Lair. I say potential because changes to the classic ROM would be required to fully exploit this feature on a day-to-day basis, but user code can take advantage of it. I suppose this is where the red line exists for the back-porting of features - if a change to the ROM is required then the feature stays as plus only.

So in all honesty if you have a fully loaded ZXpand+AY then you won't benefit from splashing cash, unless you want a more compact arrangement on your desk.

Re: ZXpand vs ZXPand+

Posted: Wed Jul 12, 2017 5:40 pm
by Moggy
Whilst I cannot comment on the technical aspects of the spand plus, I can say that having used the prototype firmware and MIDI player Sir Morris is developing (every day since the 22nd of June) that it is in my opinion, as a dedicated MIDI lover for the last 35 years, about 98% complete in its functionality and the successful conversion rate of General MIDI files into a form the 81 can use is about 95%.

Without understanding the nuts and bolts of it I think the very idea of turning something too hard for the zeddy to chew into something it can easily digest is worthy of high praise whether or not you're are into MIDI or music of any kind, the technical aspect behind is lateral thinking at its very best and I'm personally much indebted to Charlie for his work in this regard.

Re: ZXpand vs ZXPand+

Posted: Wed Jul 26, 2017 8:44 pm
by tdg8934
I just purchased a ZXPand+ from the Sell my retro site. I hope to get it in time before the September 9th/10th Vintage Computer Festival MidWest in the Chicagoland area. I would like to demo the ZXPand+ and my ZXPand+AY and my new ZXmore board and MIST FPGA (for its ZX81 core and other computer gaming cores).

OK. My question to Charlie or others who have both ZXPand+ and ZXPand-AY, is on my larger ZXPand-AY (Classic) when plugged into my TS1000, I usually see some artifacting pixels on the top of the screen that may dissipate with time. I believe it might be a heating issue or power related.

Is this also seen on the ZXPand+ ?

I'm assuming this smaller design of the ZXPand+ would be rock solid in display with less heat given off.

Also - Does the ZXPand+ work with the ZXmore board? I know that my ZXPand (Classic) does not.

I'm excited to see new ZX81 products being developed and continuing Z80 technology!

Thanks - Tim

Re: ZXpand vs ZXPand+

Posted: Wed Jul 26, 2017 10:08 pm
by Lardo Boffin
Sounds like another sparkly pixel moment! Otherwise good hardware misbehaving when something is plugged in - is it anything like this


Re: ZXpand vs ZXPand+

Posted: Wed Jul 26, 2017 10:11 pm
by sirmorris
I haven't personally experienced pixel oddities when using any ZXpand. It's likely to be a function of your particular zeddy and the ZXpand. Every zeddy is different (and special! ;) Chips tend to operate within some defined range of limits, and sometimes chips are at the edge, other times in the middle. I have seen ZXpands that failed to work until I swapped chips around with others, it was possible that a set of chips would just not work together yet when part of a different set were fine.

This is just pure speculation but I suspect the ZXpand+ won't exhibit the same quirk, as it uses a different set of chips. My bet would be on memory speed. It's possible for memory to be too slow, obviously, but oddly enough too fast can be an issue too. Perhaps that's what's going on here. Of course it's impossible to say without doing some intrusive tests but it's fun to guess.

If ZXpand doesn't work with the More then it's almost certain the plus won't either as they are essentially the same at the edge connector.

I agree with you - it's a very exciting time for retroheads :D

I hope the board gets to you in time for the festival - and I hope you'll share some pictures with us too. It sounds like a great event.

Re: ZXpand vs ZXPand+

Posted: Wed Jul 26, 2017 10:45 pm
by tdg8934
Thank you. I will get pictures from the 2 day event.

I'll let you know of my findings with ZXmore and the ZXPand+.

Currently running 2.3 on ZXPand (classic) and I have to hit the reset button a couple of times to get a solid version listing and inverse K and wait for the sparkly pixels to fade. When I plug it into the ZXPand, I see 4 quadrants of graphic characters on the screen or it will scroll like the tape syncing look did. I hope it's just a problem with the ZXPand as it would be neat to see the ZXmore with a ZXPand+ plugged in as another user said he got his ZXPand to work with his ZXmore (but wondering if it was a ZXPand+ since I did not get them both ZXPand+ZXmore to work together).

My wife and I are staying over in the hotel of the event (even though Im local) and she will give me breaks to see the show. Saturday the 9th of September runs all day into the late night hours and on Sunday the event ends at 4pm.