New Acorn 8bit? Should there be one?

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1024MAK
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Re: New Acorn 8bit? Should there be one?

Postby 1024MAK » Fri Mar 31, 2017 3:03 pm

Paul, I think you misunderstand me. I'm just saying that a block transfer that does not require repeatedly re-reading of the instruction from main memory implemented as part of a CPU is equivalent to a separate DMA chip/device. The conventional CPU core section would of course be "halted" during such a block transfer operation.

By implementing it on a device that fits in the CPU socket, and as part of a "CPU" module, we can take advantage of the "CPU" address and data bus drivers etc.

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Re: New Acorn 8bit? Should there be one?

Postby paulb » Fri Mar 31, 2017 4:20 pm

1024MAK wrote:Paul, I think you misunderstand me. I'm just saying that a block transfer that does not require repeatedly re-reading of the instruction from main memory implemented as part of a CPU is equivalent to a separate DMA chip/device. The conventional CPU core section would of course be "halted" during such a block transfer operation.


I don't really think we disagreed about this. The ARM architecture pretty much does block transfers that fulfil these criteria, or at least the LDM and STM instructions should at least behave in that way, albeit not for arbitrary length transfers and only between registers and memory, but the actual sequencing must surely suspend instruction fetching because the bus is being used to transfer data.

1024MAK wrote:By implementing it on a device that fits in the CPU socket, and as part of a "CPU" module, we can take advantage of the "CPU" address and data bus drivers etc.


True enough. I was more or less thinking about the application of these techniques to existing machines as well. A piecemeal approach is worth considering here, like redoing the Plus 1 with some improvements, for instance, and then moving on to the main machine itself.

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sydney
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Re: New Acorn 8bit? Should there be one?

Postby sydney » Fri Mar 31, 2017 4:25 pm

flynnjs wrote:I would guess that we could build a Beeb FPGA motherboard to fit into a cheap netbook and with the right cheap Chinese manufacturer we could persuade them to do a small batch of keyboards and cases with different markings.


This. This is all we need.

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Re: New Acorn 8bit? Should there be one?

Postby dhg2 » Sat Apr 01, 2017 3:35 pm

Sorry if this is off-topic. I was thinking the other day, maybe it would be cool to design/create a whole new 8 bit computer, using commonly available components like TTL logic chips and stuff like that.

It would be designed to be simple as possible without compromising on functionality, so novice hobbyists who are only just starting to get into electronics might be able to build it (though by following a tutorial closely and putting effort into it).

If the design were simple enough, it might also be useful for teaching school students how computers work at the fundamental level.

If I were a rich businessman I'd seriously consider trying to start a project this. Or maybe there's already something like it.
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lazarusr
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Re: New Acorn 8bit? Should there be one?

Postby lazarusr » Sat Apr 01, 2017 4:10 pm

dhg2 wrote:Sorry if this is off-topic. I was thinking the other day, maybe it would be cool to design/create a whole new 8 bit computer, using commonly available components like TTL logic chips and stuff like that.

It would be designed to be simple as possible without compromising on functionality, so novice hobbyists who are only just starting to get into electronics might be able to build it (though by following a tutorial closely and putting effort into it).

If the design were simple enough, it might also be useful for teaching school students how computers work at the fundamental level.

If I were a rich businessman I'd seriously consider trying to start a project this. Or maybe there's already something like it.

I was at Maker Faire UK today and someone had done just that (based around a Z80 CPU). It consisted of a backplane with various plug in modules.

It was about £50 for a starter kit. No VDU output; you programmed it via a serial UART.

http://rc2014.co.uk

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Re: New Acorn 8bit? Should there be one?

Postby paulb » Sat Apr 01, 2017 4:36 pm

lazarusr wrote:I was at Maker Faire UK today and someone had done just that (based around a Z80 CPU). It consisted of a backplane with various plug in modules.

It was about £50 for a starter kit. No VDU output; you programmed it via a serial UART.

http://rc2014.co.uk


I saw this while surfing around for old parts:

PC-RETRO Motherboard Kit: IBM Clone Computer

:shock:

There's also stuff like this:

The Colour Maximite

Although it probably doesn't help that the developer of that seems to be constantly at odds with other people doing similar things. Here's one of those other things:

ELLO 2M: A DIY Computer for Hobby and Education

I also didn't realise that FUZE used this kind of hardware. (Stupid language comparison with Python on that page, where they bulk out the Python to make BASIC look more concise. Sigh.)

The PIC32 stuff is interesting because (1) it's available as a DIP product, (2) it's fairly easy to interface, and (3) it's a "real" CPU architecture (MIPS32), meaning that you can go from doing simple microcontroller things to doing what would have been workstation-class meddling back in the 1980s.

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Re: New Acorn 8bit? Should there be one?

Postby pixelblip » Wed May 03, 2017 7:47 pm

Wouldn't it be good to get a new BBC................I keep imagining the designs. I think it would have to retain the BBC shape......if you make it like a Master Compact it doesn't seem Beebish to me.......more like a traditional pc.

Is anyone tempted with the Spectrum.............
Personally I never like that style of keyboard on that model..........it was my least favourite!

The thing is if you did choose to improve the BBC and improve dthe colours / graphics and sound you sort of lose the character of the machine with it's limitations. If teletext mode was improved to allow 1 colour per pixel it wouldn't be teletext Mode7 would it!
I must admit I was jealous of C64 and the sid chip. Always wished the BBC could do bass like that ( I know you can add a SID to them now!)

A good example of this idea of upping the graphics and whether you think it's an improvement is between Speccy and the Sam Coupe - the graphics look great on the Sam Coupe and the pictures produced on it look really good but it loses that special speccy attribute clash look.....sometimes the limitations are what makes the compute....to me the Sam Coupe pictures look too polished like a DOS 256 colour image.

It will be interesting to see how the New Spectrum fairs on Kickstarter.

https://www.kickstarter.com/projects/18 ... ctrum-next

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Re: New Acorn 8bit? Should there be one?

Postby Elminster » Wed May 03, 2017 8:35 pm

paulb wrote:
I also didn't realise that FUZE used this kind of hardware. (Stupid language comparison with Python on that page, where they bulk out the Python to make BASIC look more concise. Sigh.)


:) ha yes python code is as big as possible. In reality you could write pretty much the same size. Marketing at work.

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Re: New Acorn 8bit? Should there be one?

Postby jregel » Thu May 25, 2017 9:03 pm

Should there be a new Acorn 8bit? Well, if there can be a Spectrum Next, then there should definitely be an Acorn Next :-)

But what should it look like….?

<starts daydreaming>

In keeping with the original philosophy of the Proton, that it was a multi-processor machine, I’d look to upgrade the base machine’s I/O capabilities first and then make it ready to accept internal and external co-processors. So…

- 14Mhz 65816 CPU
— Hardware mode for 65C02 compatibility for running original BBC software
— 16bit mode similar to the Acorn Communicator OS (which since it runs BBC BASIC, View and ViewSheet implies it’s not a million miles away from MOS…?)
— Advanced BASIC (containing BASIC V extensions)

- 512K-1024K RAM, possibly upgradable to 16MB

- Graphics based on the 6845 and RobC’s Palettemate VideoNuLA giving a 4096 colour palette
- Addition of the following RISC OS screen modes:
— Mode 8: 640x256 in 4 colours
— Mode 9: 320x256 in 16 colours
— Mode 10: 160x256 in 256 colours
— Mode 12: 640x256 in 16 colours
— Mode 13: 320x256 in 256 colours
— Mode 15: 640x256 in 256 colours

No need for hardware sprites when you’ve got a 14Mhz 65816. :-)

- Sound
— SN76489 (for BBC compatibility)
— In-built Music 5000 audio (via FPGA implementation)

Legacy Ports (underneath the keyboard, as expected):

- 1Mhz Bus
- User Port
- External Tube Interface

Modern Ports (on rear of machine):

- 4 x USB ports (with Datacentre-like functionality for importing disk images included)
- IDE/CF or SD card slot (with ADFS “hard disk” support)
- Ethernet Port
- HDMI video output

- Optional internal co-pro based on the Raspberry Pi Zero:
— 1Ghz ARM CPU
— 512MB RAM

All in a case similar in style to the Atom (doesn’t need to be as big as a Beeb), but with the BBC Master keyboard layout (separate numeric keypad, sensible placement of arrow keys, red function keys!).

Such a system would be a noticeable upgrade to the BBC Master, while still retaining the design and feel of the original BBC.

I’d buy that for £250, anyone want to make it? :-)

<end daydreaming>
Last edited by jregel on Mon May 29, 2017 1:21 pm, edited 1 time in total.
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paulb
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Re: New Acorn 8bit? Should there be one?

Postby paulb » Thu May 25, 2017 9:29 pm

paulb wrote:The PIC32 stuff is interesting because (1) it's available as a DIP product, (2) it's fairly easy to interface, and (3) it's a "real" CPU architecture (MIPS32), meaning that you can go from doing simple microcontroller things to doing what would have been workstation-class meddling back in the 1980s.


I finally got the PIC32 to do something half-relevant to my other retro experiments. So, I guess the result was RISC OS's mode 10 with 160x256 in 256 colours. Not really so bad for something on a breadboard.

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Re: New Acorn 8bit? Should there be one?

Postby Zarchos » Thu May 25, 2017 9:44 pm

Wow ! A goldmine of informations.
Thanks !

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Elminster
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Re: New Acorn 8bit? Should there be one?

Postby Elminster » Sat May 27, 2017 9:24 am

I vote to double BASIC ROM so extra/modern features can be added, I.e. Grab 16k of nice features from Richard's current bbc basic.

Edit: Make that quadruple, and then port BASIC V from Archie.

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Re: New Acorn 8bit? Should there be one?

Postby cmorley » Sat May 27, 2017 11:17 am

I am definitely a fan of the 8/16bit hardware from the 80s & 90s because you have a genuine chance of being able to understand how the systems work. In fact that is why I don't like the Pi - it's pretty much just a black box for most people especially as some of the IP is only available under NDA (gfx).

So a new manufactured 8-bit Acorn derivative would be kind of cool... it would be impossible to please everyone though. So IMO it would have to have a real processor and not be an emulator running on an ARM/FPGA in a box.

It would be very expensive though. Main PCB BOM £50-60 easily just for CPU, RAM, PLD & FPGA glue and BBC connectors. Add in PSU, keyboard... wow! Let alone case design and tooling... You'd need a lot of pre-sold units (crowdfund) to get that off the ground - which is getting a bad reputation with the number of failed projects walking off with £500k... they'd be £400 each easy :(

There's also the problem of licensing for various IP. Case design. OS/Software. Hell the HDMI lot will want $10,000 per year fee plus unit royalties just to put an HDMI connector on it. Add that cost on and it would be one hell of a Kickstarter project for a few years!

A PCB drop in for an original case. That's probably a better bet. Sold as a PCB kit you don't need to pay HDMI :P I'd do one of those if I thought I could sell enough! But say it came out at £150 retail and you need a donor BBC to put it in? Ouch! :S Would people pay that I wonder?

For now I'll just carry on with my trusty Bs. I'm but a pup and an amateur with only 3/1/2 - not even double figures ;)

Chris

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Re: New Acorn 8bit? Should there be one?

Postby BigEd » Sat May 27, 2017 11:40 am

A couple of interesting comments have been made on the Spectrum Next, and I'd love to know how people here feel about the same kinds of issues in the possible future situation of a Beeb Next:
- a concern that FPGA is not a valid retro implementation - would prefer a commercial CPU as a chip.
- a concern that adding a SID to a Spectrum was not consistent and was a travesty - would only accept add-ins which are faithful to the platform.

(For myself, FPGA is hardware, and perfectly valid. And any 8-bit peripheral is fine too.)

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Re: New Acorn 8bit? Should there be one?

Postby Elminster » Sat May 27, 2017 8:35 pm

Think it would be hard to come up with a spec everyone agreed with. I can't even agree with myself.

You would have to be careful going to modern or you would end up reinventing the raspberry pi.

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Re: New Acorn 8bit? Should there be one?

Postby BigEd » Sat May 27, 2017 8:49 pm

Yes, impossible to get something which everyone will agree with. But possible to build something which a lot of people will want. It's about figuring out what's generally attractive.

The advantage of an FPGA is that it can power up as one of several personalities - in our case, Atom, Beeb, Master, Elk would be good examples. And each one with or without various expansions. That makes it more attractive to more people, although of course you lose the people who insist on dedicated chips for everything.

What a Beeb Next would have to have is a beige case with decent black keyboard and red function keys. (Would that put off the Atom and Electron fans too much?)

I think getting the case design right, and sorting out the manufacturing of that, is about as big a problem as getting the spec right. You need quite a few customers signed up to make it worthwhile at a reasonable price.

The Spectrum Next is going to be field upgradeable, and open source. So any features which didn't make it into to the original spec have a chance of being implemented later. This is great because it means no great need to get the spec right for everyone: a core set of features which can be made to work and attract enough signups will do.

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Re: New Acorn 8bit? Should there be one?

Postby Elminster » Sat May 27, 2017 9:03 pm

Hmmm. Yes I am not sure about an FPGA either. Half the reason I went back to Acorn was the hardware aspect. So I am not sure what I would do with a remake as would be anything to add, solder, invent. I guess I am the wrong audience to buy one.

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Re: New Acorn 8bit? Should there be one?

Postby BigEd » Sat May 27, 2017 9:06 pm

The Spectrum Next has an FPGA inside, but a completely Spectrum-compatible edge connector on the back. So, if you don't open the case, it's just like a Spectrum, even if your thing is to add hardware to the edge connector.

So I think that's quite hopeful for a Beeb Next - only drawback is the Beeb having lots of connectors, perhaps. And the Elk and Atom having different connectors...

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Re: New Acorn 8bit? Should there be one?

Postby Elminster » Sat May 27, 2017 9:10 pm

A Beeb where you never take the case off? What a strange idea :)

I do wonder if it works better on the Spectrum as it was more of a games machine than the Beeb, which was more of an education/hobbists machine. Not sure.

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Re: New Acorn 8bit? Should there be one?

Postby BigEd » Sat May 27, 2017 9:15 pm

It's true, the Beeb is a bit special with the case coming off all the time.

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Re: New Acorn 8bit? Should there be one?

Postby 1024MAK » Mon May 29, 2017 8:16 am

Oi! My issue 1 ZX Spectrum is always naked! Mainly because it does not have a case :lol:

And there was and still is plenty of hardware tinkering with ZX Spectrums (and ZX81s for that matter). The difference being that yes, to a lot of people it was just a games machine.

One of the reasons that the SID is not popular in the Spectrum world, is that it's a lot of work to convert 6502 tunes for a Z80 based machine, and the Spectrum programmers are used to the AY sound chip. Turbo AY boards (two AY chips) have been around for a while. And AY expansions have been around since the mid 1980s. Although AY sound did not really catch on until the AY chip was included in the 128k model.

There is no reason why a new Beeb could not have a real CPU and a FPGA. Maybe with glue logic provided by a CPLD. In any event, to be compatible in speed terms, any CPU would have to slow to Beeb speed anyway...

In terms of cost, one, two or maybe three CPLD would cut out all the glue logic in a recreated Beeb. One large SRAM and one large flash ROM also help reduce the chip count. This would also significantly reduce the size of the PCB (even with plenty of extra goodies built in), leaving plenty of room for an internal expansion bus...

I'm not at all bothered about HDMI. Only the TV in the living room (which is computer free) has any HDMI connected devices with one exception:- I do use a RGB SCART to HDMI converter box with my QL so that the QL can be used in "monitor" mode.

So with a new Beeb, I would be happy with RGB analogue, RGB TTL (like existing Beebs) and SVGA outputs. If a user needed HDMI, they could use a converter box.

As said above, the biggest problem is the keyboard and the case due to both the set-up/tooling cost and the actual production cost :(

So maybe the way to go is to start with just new keyboards and new cases. After all, there are at least some users who would just want a new fully working trouble free keyboard and a nice new clean case. They could then fit an existing Beeb PCB in said case.

Then either one new design, or maybe various different new Beeb PCBs could be produced to fit both existing cases and of course, the new cases.

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Re: New Acorn 8bit? Should there be one?

Postby Elminster » Mon May 29, 2017 10:01 am

They pump out new cases for amigos a1200 in a number of colours. Good start for beeb

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Re: New Acorn 8bit? Should there be one?

Postby BigEd » Mon May 29, 2017 10:32 am

That's a good case study(!) - they got 840 signups, raised 150k. They'd set the minimum at 125k. That matches my own guess that 1000 signups is about the necessary level to get into custom injection moulding - Spectrum Next got three times as many, but again the minimum they set for viability was 250k - about a 1000 signups.

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Re: New Acorn 8bit? Should there be one?

Postby Elminster » Mon May 29, 2017 1:58 pm

Quite fancy a blue case or maybe black.

Keyboard might be an idea with the gradual drying up of supplies of keypresses. Not sure what modern key presses you can get that would give that distinctive clack.

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Elminster
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Re: New Acorn 8bit? Should there be one?

Postby Elminster » Sun Jun 18, 2017 5:01 pm

1024MAK wrote:Oi! My issue 1 ZX Spectrum is always naked! Mainly because it does not have a case :lol:

#-o

There is no reason why a new Beeb could not have a real CPU and a FPGA. Maybe with glue logic provided by a CPLD. In any event, to be compatible in speed terms, any CPU would have to slow to Beeb speed anyway...


Not really much choice but to use FPGA, microprocessors etc. As no one seems to make anything for sound or gfx anymore, so doing mass volume would be hard. Quite like the look of the Propeller which already has most of these chips.

Generally BigEd is on most of the interesting posts about video/sound over on 6502.org

I see that as the big debate. The cpu, via, serial etc are all still made.

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Re: New Acorn 8bit? Should there be one?

Postby algenon_iii » Thu Jun 29, 2017 5:40 pm

Just seen this discussion, so here's my 2p worth.

The idea sounds good and the possibility of making it multi-Acorn 8-bit sounds cools as well. Adding 4096 would be appropriate as well considering that the chameleon board added this capability to the original. Data Centre style USB and CF(IDE) / or GoMMC/SD storage capabilities are a must as well.

Case-wise I think the electron was probably the best looking one (the beeb and master are functional behemoths), but it has disadvantage of not being as well known as the beeb, but that's an advantage as well as a lot of people just know the beeb as the school computer. So might associate it with things like educational games, wordwise and view(sheet), not fun games (expect perhaps granny's garden).

Personally speaking the Master Compact 'keyboard' was the best of the beeb cases, so that might be a good basis for a new design. The colour scheme makes it recognisable as a beeb, yet it's not quite as bulky as the beeb or master.


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