Search found 58 matches

by cjm
Sat Feb 20, 2021 5:49 pm
Forum: acorn atom and acorn system series
Topic: Interfacing an Atom to a Raspberry Pi Pico
Replies: 16
Views: 556

Re: Interfacing an Atom to a Raspberry Pi Pico

A Pico version of AtoMMC would definitely be possible, and it would be much faster than the current PIC/AVR versions. Update: a functioning RPi Pico AtoMMC. It is about 4 times faster than the PIC version. pico-mmc.png kudos to the original developer(s) (Charlie Robson?) - the Pico firmware is a re...
by cjm
Sat Feb 06, 2021 4:37 pm
Forum: acorn atom and acorn system series
Topic: Interfacing an Atom to a Raspberry Pi Pico
Replies: 16
Views: 556

Re: Interfacing an Atom to a Raspberry Pi Pico

; tDB is the delay between the rising edge of a signal and when it's safe to start ; looking for the falling edge. It's used mostly on Phi2, which can suffer noise ; due to crosstalk from the data bus being driven That's really useful to know - I came up with the same solution - I thought it was ju...
by cjm
Fri Feb 05, 2021 10:15 pm
Forum: acorn atom and acorn system series
Topic: Interfacing an Atom to a Raspberry Pi Pico
Replies: 16
Views: 556

Re: Interfacing an Atom to a Raspberry Pi Pico

Hi David, The atom->pico i/f code is now here: https://github.com/cmoulang/atom-pico-test It is connected as follows: GP4 NB400 GP5 NRST GP6 1MHz Clock GP7 R_NW GP8-15 D0-D7 GP16-19 A0-A3 ?#B40F=255 will run the built in logic analyser on the second CPU. A read or write to the PL8 will trigger it. O...
by cjm
Fri Feb 05, 2021 7:06 pm
Forum: acorn atom and acorn system series
Topic: Interfacing an Atom to a Raspberry Pi Pico
Replies: 16
Views: 556

Re: Interfacing an Atom to a Raspberry Pi Pico

I'm happy to swap ideas, I'm sure you're way ahead of me! I'll put the project on github and share a link later this evening.

Chris
by cjm
Fri Feb 05, 2021 6:38 pm
Forum: acorn atom and acorn system series
Topic: Interfacing an Atom to a Raspberry Pi Pico
Replies: 16
Views: 556

Interfacing an Atom to a Raspberry Pi Pico

A quick demo of the Pico's programmable input/output (PIO) being used to exchange data over the Atom's PL8 interface. pico1.jpg A level converter and a patch cable provide the connection to the Pico pico2.jpg The demo software running on the Pico provides the Atom with 16 8-bit registers in the rang...
by cjm
Wed Jan 20, 2021 10:11 pm
Forum: acorn atom and acorn system series
Topic: Atom Video to HDMI Adapter
Replies: 269
Views: 26581

Re: Atom Video to HDMI Adapter

Clever =D>
by cjm
Wed Jan 20, 2021 9:27 pm
Forum: acorn atom and acorn system series
Topic: Atom Video to HDMI Adapter
Replies: 269
Views: 26581

Re: Atom Video to HDMI Adapter

How do you get blues and oranges form an Atom as shown in the first post? (reproduced below)

My Atom and the Atomulator only seem to have 4 colours; green, yellow, red and black in mode 0. Is there another text mode?


capture0.png
capture0.png (34.83 KiB) Viewed 217 times
by cjm
Tue Dec 22, 2020 11:16 am
Forum: acorn atom and acorn system series
Topic: New AtoMMC board: V4
Replies: 70
Views: 3717

Re: New AtoMMC board: V4

I know it's pointless but here is Chuckie Egg with Kees's patch running at 4MHz

https://youtu.be/m-xtkX5JEPw
by cjm
Sun Dec 20, 2020 9:08 pm
Forum: acorn atom and acorn system series
Topic: USB Gamepad to AtoMMC Joystick Adapter
Replies: 0
Views: 491

USB Gamepad to AtoMMC Joystick Adapter

Here are some photos of a RPi zero interfacing a USB game pad to my newly acquired AtoMMC. (The orange insulator is an old credit card) gp3.jpg The purpose is to use this as a joystick. gp1.jpg It fits inside the Atom case - just the USB socket visible. gp6.jpg Close up of the connector - a repurpos...
by cjm
Fri Dec 18, 2020 8:44 pm
Forum: acorn atom and acorn system series
Topic: New AtoMMC board: V4
Replies: 70
Views: 3717

Re: New AtoMMC board: V4

oss003 wrote:
Fri Dec 18, 2020 7:25 pm
... are the games still playable at 4 Mhz?
Probably not - but Chuckie Egg at 4MHz ! :lol:
by cjm
Fri Dec 18, 2020 7:02 pm
Forum: acorn atom and acorn system series
Topic: New AtoMMC board: V4
Replies: 70
Views: 3717

Re: New AtoMMC board: V4

Thanks Kees, That's it! I get 11111111 at 2MHz with that patch and setting ?#2866=16 works for 4MHz Regards, Chris Nice ..... 16 should also work for 1 and 2 Mhz. Greetings Kees The problem is that I will need to patch Chuckie Egg to run it at 4MHz :( A better solution would be a patch to the AtoMM...
by cjm
Thu Dec 17, 2020 10:25 pm
Forum: acorn atom and acorn system series
Topic: New AtoMMC board: V4
Replies: 70
Views: 3717

Re: New AtoMMC board: V4

Thanks Kees,

That's it!

I get 11111111 at 2MHz with that patch and setting ?#2866=16 works for 4MHz

Regards,
Chris
by cjm
Thu Dec 17, 2020 8:48 pm
Forum: acorn atom and acorn system series
Topic: New AtoMMC board: V4
Replies: 70
Views: 3717

Re: New AtoMMC board: V4

There seems to be a problem with reading the joystick port (portb) when running at 2/4 MHz. With no joystick attached you would expect the port to read 11111111(binary) which it does correctly at 1 MHz. However at 2/4 MHz the value is 10000000 - this is not correct. It looks like the AtomMMC writes ...
by cjm
Tue Dec 15, 2020 6:48 pm
Forum: acorn atom and acorn system series
Topic: New AtoMMC board: V4
Replies: 70
Views: 3717

Re: New AtoMMC board: V4

My new AtoMMC V4 board arrived today. It took 5 minutes to fit and of course, it goes without saying that it worked first time.

Here it is with Hoglet's software archive.
atommcv4.jpg
by cjm
Sun Nov 29, 2020 9:55 pm
Forum: acorn atom and acorn system series
Topic: New AtoMMC board: V4
Replies: 70
Views: 3717

Re: New AtoMMC board: V4

CommanderCoder wrote:
Tue Nov 24, 2020 3:36 pm
It's one of these that I found in the bottom of a drawer. I may have loaded it with a bit too much solder!

https://uk.rs-online.com/web/p/slide-switches/0337497/
Try a better switch, that one is rated at 300mA the Atom can draw 10x that.
by cjm
Tue Nov 17, 2020 4:49 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

DaveLecky wrote:
Tue Nov 17, 2020 3:18 pm
Hi Folks,

Would changing the two crystals be worthwhile...?

Dave
If there is a clock issue then it's worth trying the mod again but this time with pin 10 of IC44 bent out.

viewtopic.php?f=44&t=19947&p=278886#p278886

Chris
by cjm
Tue Nov 17, 2020 2:26 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

DaveLecky wrote:
Tue Nov 17, 2020 2:22 pm
Hi cjm, that was a misprint, it was out after your tests.

Dave
OK - it needs to be out for those mods to work. I'll update my earlier post to make that clear.
by cjm
Tue Nov 17, 2020 2:15 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

DaveLecky wrote:
Tue Nov 17, 2020 10:39 am
Hi Chris,

Yes, the pin was out ok at installation, I did reinsert it during your tests, it is back in now.

Dave
That might be your problem - pin 10 on IC44 should not be connected when the YARRB is installed.
by cjm
Mon Nov 16, 2020 10:01 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

Hi Folks, I have applied the changes suggested by cjm, the Atom showed the same results as in the following link. :( It did however appear to go faster than before. https://stardot.org.uk/forums/viewtopic.php?f=44&t=18020&start=210#p294864 The changes.... 55B058C3-B73E-4217-8CD0-85F795A5684...
by cjm
Tue Nov 10, 2020 7:36 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

Your 8255 is set to clear 3, we have seen this in the past. Unfortunately it's not just a setting. It is related to the clock signal. Some people solved it by replacing the 8255. Also adding a 100 ohm resistor in the clock wire that you soldered did in some cases solve the issue. The best way might...
by cjm
Tue Aug 18, 2020 8:55 pm
Forum: acorn atom and acorn system series
Topic: My first Atom....
Replies: 26
Views: 1724

Re: My first Atom....

++ to Kees suggestion regarding switching the 2114's around - it worked for me.

Another possibility is that the system clock is not working - if you have an oscilloscope measure pin 37 of the CPU, it should have a 1 MHz signal on it.
by cjm
Tue Aug 04, 2020 12:04 pm
Forum: acorn atom and acorn system series
Topic: My first Atom....
Replies: 26
Views: 1724

Re: My first Atom....

Recomendations for power supplys?, none came with it so look to fit LK6/7 and use a 5V Regulated one. Congrats on your new Atom! I couldn't find a power supply with the right connector for my Atom - so I replaced the connector and used one of these: https://www.ebay.co.uk/itm/5V-4A-AC-DC-Switching-...
by cjm
Sat Aug 01, 2020 10:30 am
Forum: past all-day virtual ABugs
Topic: All-day 'Virtual' Acorn session #6, Saturday 1st August 2020, 9am - 11pm [NOW FULL!]
Replies: 105
Views: 7199

Re: All-day 'Virtual' Acorn session #6, Saturday 1st August 2020, 9am - 11pm [NOW FULL!]

Hi,

I would like to join this afternoon's session if any spaces become available.

Chris.
by cjm
Wed Jul 29, 2020 10:48 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

stuff.zip
decoder.vhd
(2.78 KiB) Downloaded 18 times
by cjm
Wed Jul 29, 2020 10:45 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

Nice work =D> IIRC Hoglet has a Yarrb1 board, perhaps he can check if this mod also works on those boards as will. I think it should. I guess that The 6522 timers won't work at 4MHz since the clock is only stretched when the cpu addresses the bxxx block. In other memory areas it is running ax maxim...
by cjm
Wed Jul 29, 2020 9:40 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

That looks good. Did you kick out the 4MHz mode? It seems to me that you could do the same trick for turbo mode.... (?) Good point - it took a bit of head scratching but the Atom is now working at 4 MHz with the clock stretching logic. Faster than a BEEB! and Chuckie Egg is still playable :D 124MHz...
by cjm
Tue Jul 28, 2020 8:39 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

Hi Roland - thanks for making the source available. I have modified the VHDL to stretch the p0 clock when accessing the 8255 PPI that controls the keyboard. So the Atom can run at 2 MHz but access the slower peripherals at 1 MHz. Result: I can play Chuckie Egg at 2 MHz :D IMG_4671.jpg IMG_4669.jpg V...
by cjm
Mon Jul 27, 2020 11:52 am
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

That works. Thanks.
by cjm
Sun Jul 26, 2020 11:00 pm
Forum: acorn atom and acorn system series
Topic: Yarrb - redesigned
Replies: 288
Views: 19465

Re: Yarrb - redesigned

Has anyone managed to build and program the VHDL for the yarrb2 from: https://github.com/AtomicRoland/yarrb2-cpld? If I build the github code the yarrb2 works well enough to boot the Atom but the useless leds don't work and the BFFE register shows the wrong value and cannot be altered. Is there some...
by cjm
Sat Jul 18, 2020 11:01 pm
Forum: acorn atom and acorn system series
Topic: YARRB [SOLD OUT]
Replies: 287
Views: 31208

Re: YARRB [SOLD OUT]

I have done some testing on an Atom with following the clock modification: The modifications will be simple: move the flying wire from pin 13 to pin 11 (that's a 2MHz "buffered" clock IIRC). For a CMOS cpu this will work but the cpu will be running at 500kHz. By switching to 1 MHz (i.e. th...

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