ZX Spectrum next... Anybody backing ?

Talk about non-Acorn classic computers/hardware/software here (including retro consoles)
User avatar
lazarusr
Posts: 620
Joined: Thu Sep 10, 2015 8:56 pm
Location: London

Re: ZX Spectrum next... Anybody backing ?

Postby lazarusr » Tue Jul 25, 2017 7:26 pm

Just received the latest update. They are apparently adding a DMA controller to the design. I'm not sure how I feel about that. Seems to be a step too far from the basic nature of the original
Speccy.
Last edited by lazarusr on Tue Jul 25, 2017 10:08 pm, edited 1 time in total.

User avatar
fordp
Posts: 919
Joined: Sun Feb 12, 2012 9:08 pm
Location: Kent, England

Re: ZX Spectrum next... Anybody backing ?

Postby fordp » Tue Jul 25, 2017 10:07 pm

DMA will be great.for new advanced features the old ROMs will not use it of course.
FordP (Simon Ellwood)
Time is an illusion. Lunchtime, doubly so!

User avatar
vanpeebles
Posts: 397
Joined: Wed Nov 28, 2012 10:01 am
Location: UK
Contact:

Re: ZX Spectrum next... Anybody backing ?

Postby vanpeebles » Wed Jul 26, 2017 8:01 am

I have an mb02, and I'm sure that had DMA.

Andrew_Waite
Posts: 34
Joined: Tue Aug 30, 2016 2:58 pm

Re: ZX Spectrum next... Anybody backing ?

Postby Andrew_Waite » Wed Jul 26, 2017 5:13 pm

The Spectum-DMA hack that has now been implemented into the 'NEXT' is a modification for the ZX Spectrum that seems to go back as far as the Czech Republic in the 1990s. The Spectrum's Z80 is moved to a daughterboard with a Z80DMA chip and some glue logic inside a GAL16V8, the daughterboard is then connected into the Spectrum's CPU socket.

There is more information on this modification here :

http://velesoft.speccy.cz/data-gear.htm

https://www.youtube.com/watch?v=eiD45DRGtuI

To my mind the idea behind this modification is as brilliant as it is simple, and I wonder if it can be applied to other machines with CPUs that can be tri-stated such as the BBC B+?

User avatar
fordp
Posts: 919
Joined: Sun Feb 12, 2012 9:08 pm
Location: Kent, England

Re: ZX Spectrum next... Anybody backing ?

Postby fordp » Wed Jul 26, 2017 6:32 pm

Hoglets FPGA ( previously GODIL) based "6502" would be a good candidate for having DMA added.
FordP (Simon Ellwood)
Time is an illusion. Lunchtime, doubly so!

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Fri Nov 24, 2017 1:15 pm

just thought i would pop in to say hello!

AM part of the gui team on the next, and we were getting interested in the pi acceleration work that was done here.

There is mixed feelings about getting the z80 to run more than 40mhz. Some folk seem to think thats the devils work! [-X

personally am all for it. AM curious to see how fast it could actually go.

Officially the boards get posted next week, so hopefully have one within 7 days, to fiddle with....

its possible the core could be altered to run a modified version of a risc cpu. all depends on size i guess. some details are still sketchy atmo, but should be revealed very soon!

User avatar
BigEd
Posts: 1484
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Fri Nov 24, 2017 1:26 pm

Welcome northernbob! There are certainly at least two schools of thought about what kind of thing is an acceptable thing. The best approach, I think, is to stick to the kinds of things you find acceptable and avoid arguments about what's in and what's out.

For myself, I'll be waiting a bit longer because I ordered a cased Next. But as far as I can tell, it should make for a very flexible platform. (And for me, the faster the better!)

I see nearby the ZX-Uno is being used in a very flexible way:
viewtopic.php?p=184740#p184740

User avatar
1024MAK
Posts: 6786
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...

Re: ZX Spectrum next... Anybody backing ?

Postby 1024MAK » Fri Nov 24, 2017 3:26 pm

Only two camps :shock:

I think you find I'm the third way :lol:

I have both original systems and FPGA based systems. I also have my fingers near to a PI, but have not done that much with them so far...

But, the Acorn BBC Micro was designed with another (faster, more powerful) processor in mind. The ZX Spectrum was designed to be as inexpensive as possible, so as to appeal (and be affordable) to the ordinary person. But the Z80 CPU was designed to give up control of the memory and I/O system... And the Timex disk system (for the Timex version of the ZX Spectrum) was a computer in it's right...

I too went for a cased model.

Mark
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk NOW!
BeebWiki‬ - for answers to many questions...

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Fri Nov 24, 2017 9:46 pm

BigEd wrote:
I see nearby the ZX-Uno is being used in a very flexible way:
viewtopic.php?p=184740#p184740


that thread is a bit rambling, but do i take it there is problems porting the beeb core over?

has anyone tried doing the pi accelerator trickz on a fpga machine? am curious to see how fast its going to run on the next board.

atmo, I dont fully understand how to accelerate the tbblue core, using the methods invented in this thread....
viewtopic.php?f=3&t=11325&start=960#p186726

perhaps we could start a bit of a think tank, and have ago ??

User avatar
BigEd
Posts: 1484
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Fri Nov 24, 2017 10:03 pm

I think all the problems were resolved as various things being out of date or missing known fixes.

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Sat Nov 25, 2017 9:50 am

are there any cores in development that are more advanced than the bbc b ?

i doubt the Archimedes is small enough to fit. Anyone worked on a more advanced version of the master?

I think this is the fastest route to getting a gui working on the next. eg gem.

it could take weeks or months to get the z80 properly accelerated...ofcourse the next community want to see a gui with a z80 at the heart of it, and no variation.

the next of course was marketed on the nostalgia factor and its attracted alot of folk with a backwards looking mentality. whihc is awkward, moving forward, but i understand the marketing decision.....£ as always!

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Sat Nov 25, 2017 10:18 am

btw am supposed to have 3 boards arrive next week.

anyone here who lives near weston and wants to have a go on one, i only charge onepint an hour :lol:

maybe we can arrange a meetup/workshop thing?

Zeb
Posts: 12
Joined: Mon Oct 19, 2015 4:45 pm

Re: ZX Spectrum next... Anybody backing ?

Postby Zeb » Sat Nov 25, 2017 11:48 am

A pint? I'm a light weight so my fee stands at half a pint an hour and I'm by Exeter 8)

I've got a couple machines with my name on. I went for the board only as an extra because they were supposed to be shipped in August but due to the unforseen delay sourcing the RAM sockets, it's now going to be a little later. I can see my board only ending up on eBay together with modified old Spectrum cases (rubber key and Spectrum+) and full 2MB RAM once my boxed one arrives.

User avatar
1024MAK
Posts: 6786
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...

Re: ZX Spectrum next... Anybody backing ?

Postby 1024MAK » Sat Nov 25, 2017 2:07 pm

Hello northernbob

Welcome :D

northernbob wrote:btw am supposed to have 3 boards arrive next week.

anyone here who lives near weston and wants to have a go on one, i only charge onepint an hour :lol:

maybe we can arrange a meetup/workshop thing?

You may have to be a bit more specific, as there are over 20 places named "Weston" or with "Weston" in the name...

Tell us all about yourself in the introduce yourself topic :wink:
Put yourself on the map by sticking a pin in it at this link :P

Mark
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk NOW!
BeebWiki‬ - for answers to many questions...

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Sun Nov 26, 2017 3:48 pm

pffft there is only one weston!

john Cleese will tell you that too :)

User avatar
1024MAK
Posts: 6786
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...

Re: ZX Spectrum next... Anybody backing ?

Postby 1024MAK » Sun Nov 26, 2017 6:32 pm

northernbob wrote:pffft there is only one weston!

john Cleese will tell you that too :)

My home town then :D

Mark
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk NOW!
BeebWiki‬ - for answers to many questions...

crj
Posts: 315
Joined: Thu May 02, 2013 4:58 pm

Re: ZX Spectrum next... Anybody backing ?

Postby crj » Mon Nov 27, 2017 12:33 am

northernbob wrote:pffft there is only one weston!

Weston the Wonder Horse?

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Wed Nov 29, 2017 8:50 am

1024MAK wrote:
northernbob wrote:pffft there is only one weston!

john Cleese will tell you that too :)

My home town then :D

Mark


ive been workingin burnham during the summer, but am in weston once a week, sometime more. was gonna pm you but forum wont let me....it knows am still a clueless nuuub )

User avatar
danielj
Posts: 5337
Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester

Re: ZX Spectrum next... Anybody backing ?

Postby danielj » Wed Nov 29, 2017 9:12 am

Your PMs will work now, just ask and they can be enabled (assuming we don't think you're a charlatan hell-bent on spamming everyone ;) ) :D

d.

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Wed Nov 29, 2017 9:15 am

to misquote Frankenstein...

its alive alive!!

pm sent)

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Wed Nov 29, 2017 9:32 am

erm......at the risk of sounding like a gobshite...

would anyone like a hand in influencing the future direction of the next?!

COme and join team gui, and lets make the future together.

ok sorry i got carried away there. ill step back from the marketing hype!

https://www.facebook.com/groups/772267459595751/

come take a peek at what we are upto )

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Wed Nov 29, 2017 9:54 am

btw....

we were working with this lad, to help us get the gui running, but tbh we had communication problems. hes brazilian, and he just didnt really get what we were saying, and/or he didnt really care.

https://acassis.wordpress.com/2017/11/2 ... -on-nuttx/

he was involved in getting nuttx to run on the pizero, which might be of interest to folk! i suspect some of you will have heard of gregory nutt?

so far , we have failed to make use of nuttx on the next. if my understanding is correct(maybe not) then we need a hypervisor to get nuttx to play ball the an accelerated next.....eg once the pizero has booted with a bare metal os. maybe you lads know if nuttx would sit well ontop of a bare metal os??

tbh am at the fringes of my knowledge here.

User avatar
BigEd
Posts: 1484
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Wed Nov 29, 2017 4:35 pm

NuttX is new to me, but seems interesting: a small real-time multiplatform Unix-like OS, BSD-licensed.

I would use the terminology this way:
- an application usually runs on top of an OS
- an OS usually runs on top of bare metal
- sometimes, unusually, an application runs on top of bare metal (PiTubeDirect is an example)
- sometimes an OS runs on a virtualised machine provided by a lower-level OS, which might be a hypervisor.

So, for me NuttX is an OS, as is Linux, and either should in principle run on a Pi. Certainly linux does! As does RISC OS. But I don't see - from a quick search - that NuttX has yet been ported to the Pi.

The Spectrum Next offers an FPGA with lots of local RAM and a connection to a Pi. There are surely several ways in which the Pi and the FPGA could cooperate to provide an interesting user experience. One way would be to run Linux on the Pi and have the FPGA act as a hardware accelerator, or act as a complex hardware user interface (handling sound, video, etc). Another way would be to have the FPGA act as a host micro and have the Pi emulate an accelerator - somewhat like the Beeb and PiTubeDirect. There are perhaps an endless variety of ways, so the crucial question is who has both a workable idea and the skills to implement it.

crj
Posts: 315
Joined: Thu May 02, 2013 4:58 pm

Re: ZX Spectrum next... Anybody backing ?

Postby crj » Wed Nov 29, 2017 7:07 pm

BigEd wrote:The Spectrum Next offers an FPGA with lots of local RAM and a connection to a Pi. There are surely several ways in which the Pi and the FPGA could cooperate to provide an interesting user experience.

I've looked at the idea of Pi + FPGA in other contexts and decided it's surprisingly difficult to make anything interesting happen. )-8

There's simply no opportunity for a high-bandwidth low-latency link between the two. Particularly, no way to have the FPGA appear as memory-mapped I/O for the Pi. The best you can do seems to be SPI (which seems to max out at 25Mbps, though some people have struggled to get 10Mbps and a lucky few have reported a bit more on the 3) or bit-bashing, which as PiTubeDirect has demonstrated is close to the wire at 2MHz even without an OS or any general-purpose application software on the Pi.

What you can achieve is closer to the stuff you'd do with USB or a LAN.

Meanwhile, for the things the Pi is good at, i.e. general purpose compute and especially graphics, the FPGA won't hold a candle to it, so there's no scope for acceleration. What the FPGA is good at is time-accurate emulation of complex hardware. Which is exactly what it's being used for in the Spectrum Next. (-8

User avatar
BigEd
Posts: 1484
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Wed Nov 29, 2017 7:14 pm

I'm sure you could do heaps better than 2MHz, if the interface were designed for bit-bashing by the Pi. It's the tricky slaving to a 2MHz master which is the limitation, meeting setup times intended for TTL implementations.

[Dave (hoglet) has transferred data from ARM to FPGA on the BlackIce, using SPI I think.]

crj
Posts: 315
Joined: Thu May 02, 2013 4:58 pm

Re: ZX Spectrum next... Anybody backing ?

Postby crj » Wed Nov 29, 2017 8:14 pm

This suggests the maximum rate you can achieve bit-bashing a single wire is 22MHz.

There are 26 GPIOs, and turning a GPIO around between read and write looks like a way slower operation, so what with needing other pins for input and a few for control you probably could only have an 8-bit parallel output bus. And you'd have to not care that you were setting lines low on falling clock edges and high on rising.

I don't believe the DMA controller can perform such operations, so that would be 22Mbytes/sec if you dedicated the Raspberry Pi flat-out. Google isn't finding me anybody actually achieving that throughput... which is in any case still slower than USB2 (albeit at far lower latency).

By comparison, though, STM32s can memory-map QSPI peripherals at up to 80MHz DDR. So 80Mbytes/sec on a six-wire bus, and you can even execute code from it if you like.

northernbob
Posts: 39
Joined: Fri Nov 24, 2017 6:49 am

Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Wed Nov 29, 2017 8:57 pm

crj, just chking you have seen this....

https://gitlab.com/victor.trucco/TK-Pie

maybe nothing new there that hoglet hasnt done already, but you can have a peek )

is there no data from the pi3 ? the article you link is from 2015.

crj
Posts: 315
Joined: Thu May 02, 2013 4:58 pm

Re: ZX Spectrum next... Anybody backing ?

Postby crj » Thu Nov 30, 2017 12:43 am

I hadn't seen that, no - I don't normally follow Sinclair retrocomputing... unless it pops up on Acorn forums. (-8

It seems to be doing very much the same thing as PiTubeDirect. The different trade-offs I immediately spot are:
  • It's got to run at 3.5MHz instead of 2MHz
  • ...but if it misses a write there's just an incorrect display until the next write to that location, so the robustness requirement is lower
  • ...and it's read-only, so the ARM has to perform a third as many GPIO accesses
  • ...and there's a CPLD which gives it longer to read each value before it goes away
That sort of bit-bashing seems to be right on the cusp of what's possible with a Raspberry Pi.

User avatar
BigEd
Posts: 1484
Joined: Sun Jan 24, 2010 10:24 am
Location: West
Contact:

Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Thu Nov 30, 2017 7:40 am

With that external latch, it only has to keep up with approx 1MHz memory writes, I think - a much easier problem. Snooping all writes is an interesting idea though.

crj
Posts: 315
Joined: Thu May 02, 2013 4:58 pm

Re: ZX Spectrum next... Anybody backing ?

Postby crj » Thu Nov 30, 2017 5:16 pm

Mmm. I've contemplated the same idea in a BBC Micro in order to mirror its display into a VNC server. (-8


Return to “other vintage computer hardware, software and games”

Who is online

Users browsing this forum: No registered users and 3 guests