change the core

Time to talk about what other machines can run on the Next hardware!
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Northernbob
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change the core

Post by Northernbob » Fri Dec 08, 2017 3:10 am

what is the simplest way to do this?

got a mate who wants to try out a BBC core. BEcause there is a load of software already written to accelerate a a 6502, using the pi. SO in theory it should be relatively simple to get it working on the fpga. In reality, nothing ever is )

As i have a spare board, i can afford to let him use the other one to play about with.

SOme one written down the procedure yet? one line per action.

eg make it fool proof :lol:

one thing that occurs to me....changing to say a beeb core....how does it see the keyboard? if you have ps2 pluggedin.

Northernbob
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Re: change the core

Post by Northernbob » Fri Dec 08, 2017 6:56 pm

some questions that have been raised....

How are accel_io(27 downto 0) wired to the 40-pin connector? (Knowing this will let us add support Pi Tube Direct)

- Is csync_o connected to the VGA connector? Or to somewhere else? It seems the RGB usage of the VGA connector is not well documented: viewtopic.php?f=6&t=820

- What are i2c_scl_io and i2c_sda_io connected to? The DS1307 RTC chip (not fitted)?

- What does audioint_o do?

- Why is mic_port_o an output and ear_port_i an input. This seems the wrong way around.

- What does joysel_o do? I'm guessing it controls a multiplexer to select between the two joystick ports.

- What does joyp7_o do?

- Which chip select should be used for the main SD Card? sd_cs_n_o or sd_cs2_n_o?

- How are the ram_cs_o routed to the RAM chips? i.e. which chip select should is used for the RAM that drives ram_data_io (7 downto 0).

- Are there really no LED driven from the FPGA?

- What's the part number of the 8-pin Winbond? FLASH?

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mcleod_ideafix
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Re: change the core

Post by mcleod_ideafix » Sat Dec 09, 2017 12:12 am

Northernbob wrote:
Fri Dec 08, 2017 6:56 pm
- Is csync_o connected to the VGA connector? Or to somewhere else? It seems the RGB usage of the VGA connector is not well documented: viewtopic.php?f=6&t=820
Most probably, some unused pin on the VGA connector, but the pinout has not been disclosed yet.
Northernbob wrote:
Fri Dec 08, 2017 6:56 pm
- What are i2c_scl_io and i2c_sda_io connected to? The DS1307 RTC chip (not fitted)?
Yes, that is the I2C bus.
Northernbob wrote:
Fri Dec 08, 2017 6:56 pm
- What does audioint_o do?
It's the connection to the internal (not fitted) speaker.
Northernbob wrote:
Fri Dec 08, 2017 6:56 pm
- Why is mic_port_o an output and ear_port_i an input. This seems the wrong way around.
No, it's actually right. MIC is an output on the original Spectrum and EAR, an input. On 48K models, both functions share the same pin, but on later 128K models, there were two different pins from the ULA.
Northernbob wrote:
Fri Dec 08, 2017 6:56 pm
- Which chip select should be used for the main SD Card? sd_cs_n_o or sd_cs2_n_o?
My guess is that it should be sd_cs_n_o
Northernbob wrote:
Fri Dec 08, 2017 6:56 pm
- What's the part number of the 8-pin Winbond? FLASH?
I've been told it's a 25Q128 chip.

Sorry, I cannot answer all your questions. All I have is the UCF file. No schematics and no real board in front of me :)
http://www.zxuno.com
ZX-Uno · FPGA ZX Spectrum clone.

Northernbob
Posts: 157
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Re: change the core

Post by Northernbob » Sat Dec 09, 2017 9:17 am

some progress beingmade....

https://github.com/hoglet67/BeebFpga/bl ... c_next.vhd

https://github.com/hoglet67/BeebFpga/bl ... _next.xise

prob gonna take a while, but the lads on the ball!!

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Richard Hallas
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Re: change the core

Post by Richard Hallas » Sat Dec 09, 2017 12:00 pm

Brilliant. Addition of BBC Micro to the range of Next options is something I'd very much like to see. (As a Spectrum owner in the 80s, the BBC was my 'other machine'.)

Richard Hallas
(Join the Jet-Set! • Jet Set Willy in Space • A Miner Triad)

stephenvalente
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Re: change the core

Post by stephenvalente » Sun Dec 10, 2017 9:48 am

I'm looking for an old BBC machine as like the look of using the Pi Zero as a co-processor

http://www.sundby.com/index.php/pitubedirect-2/

Northernbob
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Re: change the core

Post by Northernbob » Sun Dec 10, 2017 10:50 pm

stephenvalente wrote:
Sun Dec 10, 2017 9:48 am
I'm looking for an old BBC machine as like the look of using the Pi Zero as a co-processor

http://www.sundby.com/index.php/pitubedirect-2/
erm why bother, if they going to get the same thing running on the next? unless they hit a technical hitch ofcourse!

did you know that bloke is in the gui grp?(sundby) but he makes F all contribution.... :|


Bleugh
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Re: change the core

Post by Bleugh » Mon Dec 11, 2017 1:52 pm

cool
Backer 331 - The full monty and a PCB

Northernbob
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Re: change the core

Post by Northernbob » Mon Dec 11, 2017 8:08 pm

http://www.coocox.org/wiki/images/markd ... pi_pin.png

assume the righthand one is the pin layout on the board connector (male pins)

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