ZX Spectrum next... Anybody backing ?

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northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Sun Dec 03, 2017 12:14 pm

viewtopic.php?f=25&t=14154

may be of interest....

IF i can get a board cased up ill bring one along...

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alchresearch
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Re: ZX Spectrum next... Anybody backing ?

Postby alchresearch » Mon Dec 04, 2017 1:27 pm

Yep, I'm an Early Bird backer!
Andy Davis.

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vanpeebles
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Re: ZX Spectrum next... Anybody backing ?

Postby vanpeebles » Mon Dec 04, 2017 2:21 pm

Hi Andy, how are you doing? I used to get AlchNews, years ago :D

northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Tue Dec 05, 2017 4:51 pm

some info released today....

https://pastebin.com/TT2T53cJ

cant say i fully understand it, bits of it make sense.

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BigEd
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Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Tue Dec 05, 2017 5:00 pm

That seems to be a UCF file, which tells us what the FPGA is connected to. And its header says it's open source, which is good.
It indicates there's a 16-bit RAM (but with no byte enables) with up to 19 address bits and up to 4 chip selects
and 28 signals going off to the Pi connector
and (broadly) the expected Spectrum expansion pins (haven't checked them in detail)
and 3:3:3 bits of R:G:B
and a 50MHz input clock (although that doesn't mean a lot given the on-FPGA PLLs)
and, perhaps, output clocks at 3.5, 7, 14, 28, and a 140MHz HDMI clock.

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hoglet
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Re: ZX Spectrum next... Anybody backing ?

Postby hoglet » Tue Dec 05, 2017 5:35 pm

BigEd wrote:It indicates there's a 16-bit RAM (but with no byte enables) with up to 19 address bits and up to 4 chip selects

The RAM device used is the IDT 71V424-S10YG
https://www.idt.com/document/dst/71v424-data-sheet

This is 512K x 8, so hopefully they have given each device it's own chip select, meaning byte enables are not necessary.

See:
https://www.specnext.com/instructions-f ... ext-board/

Dave
Last edited by hoglet on Tue Dec 05, 2017 5:55 pm, edited 1 time in total.

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BigEd
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Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Tue Dec 05, 2017 5:50 pm

Interesting... so we have normally just two or maybe 4 byte-wide chips, for an 8-bit system, but we have a 16 bit wide bus to the FPGA. That's kind of handy, for later cores which are 16 bits wide - and perhaps that's the reason. I had just assumed the chips themselves were 16 bits wide, which was wild and irresponsible.

crj
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Re: ZX Spectrum next... Anybody backing ?

Postby crj » Tue Dec 05, 2017 6:14 pm

Note that external bus width and CPU microarchitecture don't need to correspond. The Motorola 68008 had 32-bit registers and a 16-bit internal data bus, but an 8-bit external data bus. Conversely, PC DIMMs are 64-bit despite being initially appearing in machines with 32-bit x86es.

northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Wed Dec 06, 2017 9:06 pm

3 boxes left for me, in the back garden by the YODEL delivery bloke!

picsin morning...

also this is waiting for me, at the local RM depot.

Image

northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Thu Dec 07, 2017 2:49 pm

for biged...

there a restriction on file size for pics?
Attachments
DSCF3110.JPG

northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Thu Dec 07, 2017 2:50 pm

couple more...(see if anyone is sharp eyed)
Attachments
DSCF3116.JPG
DSCF3112.JPG

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BigEd
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Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Thu Dec 07, 2017 3:05 pm

Oh, very nice indeed! I see a number of resistors and resistor networks near the edge connector - I'm interested to find out how 5V-compatible it is.

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BigEd
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Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Thu Dec 07, 2017 3:12 pm

...and I see you've already fitted a Pi Zero to one of them! (Need some kind of male-to-male adapter? Or soldered a socket on the Pi?)

northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Fri Dec 08, 2017 3:19 am

so someone here familiar with accelerating a beeb core in an fpga?

eg if i let you tinker on one of my next boards, you stand a good chance of getting the pi working as a copro?

have asked for the correct procedure to change the core......https://www.specnext.com/forum/viewtopic.php?f=10&t=866

how would a beeb core understand the ps2 keyboard?

what info are we missing to try this?

mark, answer ya fbk msgs :P

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hoglet
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Re: ZX Spectrum next... Anybody backing ?

Postby hoglet » Fri Dec 08, 2017 7:58 am

northernbob wrote:how would a beeb core understand the ps2 keyboard?

Part of the Beeb core needs to map the PS/2 key codes to the BBC Key Matrix row/col, for example using a massive case statement:
https://github.com/hoglet67/BeebFpga/bl ... d.vhd#L214

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fordp
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Re: ZX Spectrum next... Anybody backing ?

Postby fordp » Fri Dec 08, 2017 8:04 am

Maybe we need a new thread for BeebFPGA on the Next?

I have a feeling this platform will be more popular than all the others put together and more. At least for me ;)

As it is a Beeb it can go in the 8 bit hardware section :D
FordP (Simon Ellwood)
Time is an illusion. Lunchtime, doubly so!

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hoglet
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Re: ZX Spectrum next... Anybody backing ?

Postby hoglet » Fri Dec 08, 2017 8:20 am

fordp wrote:Maybe we need a new thread for BeebFPGA on the Next?

Here you go....
viewtopic.php?f=3&t=14181

northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Fri Dec 08, 2017 10:30 am

erm, hope i havent put my foot in it, but ive let jim bagley know about the beeb interest in the next.

doubt hell mind or care tbh....well i dont think hes got time to care!! as you can guess the team of 4 are mentally busy, fixing bugs etc.

however he might be able to get some info out of victorT.

northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Fri Dec 08, 2017 10:59 am

for a laff...

one the lads in the gui grp came up with a new case design!!

:D
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24862090_10155124664295814_6788451682698504207_n.jpg

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BigEd
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Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Fri Dec 08, 2017 11:00 am

Have you had your three boards working yet?

northernbob
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Re: ZX Spectrum next... Anybody backing ?

Postby northernbob » Sat Dec 09, 2017 9:00 am

ok there is some confusion about my pizero.

some folk are telling me the female header is on the wrong side of the pi...i bought it off ebay like this.(see pic above)

doesnt this only matter if it was going inside the official case?

little quote i saw, someone asked this...

`TBU file is the Core. FW file is the FIRMWARE (Which is a misnomer really). Imagine something like the "BIOS". You do not need a core unless you need to upgrade the hardware`

i think some chip was preflashed with the core, at the factory? u13?

sorry but info been coming thick and fast this week, and i havent retained it all....am gettin auld!
Last edited by northernbob on Sat Dec 09, 2017 9:48 am, edited 1 time in total.

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hoglet
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Re: ZX Spectrum next... Anybody backing ?

Postby hoglet » Sat Dec 09, 2017 9:16 am

northernbob wrote:some folk are telling me the female header is on the wrong side of the pi...i bought it off ebay like this.(see pic above)

The header on the Pi Zero is normally a male header, fitted to the component side. (i.e. the same as every other Pi)

If the Spec Next team has decided to use a female header on the Pi Zero and male on the Spec Next, it's anyone's guess which side of the Pi they expect it to be fitted to. This is down to how the Spec Next board has been routed.

The photo on this page does show the header on the opposite side.

Don't plug the Pi in until you are 100% sure about this.

If you have a meter, you could check which pins on the header are connected to ground.

Dave

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BigEd
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Re: ZX Spectrum next... Anybody backing ?

Postby BigEd » Sat Dec 09, 2017 10:03 am

Highly relevant blog post:
https://www.specnext.com/next-accelerator-files-v0-1/

Edit: taken down... photo might still be here:
https://www.specnext.com/wp-content/upl ... _small.jpg


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