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by Prime
Sun Aug 01, 2021 9:00 pm
Forum: 8-bit acorn hardware
Topic: 1MHz bus terminators....
Replies: 4
Views: 120

Re: 1MHz bus terminators....

dp11 wrote:
Sun Aug 01, 2021 8:09 pm
These are rarely needed.
In this case I probably don't need them, but was experiencing bad writes on the bit of hardware I'm developing, so was wanting to check it wasn't that.
Having re-factored my code it looks like it probably wasn't that :)

Cheers.

Phill.
by Prime
Sun Aug 01, 2021 6:55 pm
Forum: 8-bit acorn hardware
Topic: 1MHz bus terminators....
Replies: 4
Views: 120

Re: 1MHz bus terminators....

IanS wrote:
Sun Aug 01, 2021 6:11 pm
http://www.8bs.com/submit/acornappspdf/003.pdf

2K2, top of page 5
Humm that's what I though, guess I'm gonna have to buy some then :) I have 220R, 330R, 4k7......but not 2k2 :)

Cheers.

Phill.
by Prime
Sun Aug 01, 2021 6:07 pm
Forum: 8-bit acorn hardware
Topic: 1MHz bus terminators....
Replies: 4
Views: 120

1MHz bus terminators....

Hi all,

Can anyone remind me what values the pull up/down terminating resistors on the 1MHz bus should be please?

Cheers.

Phill.
by Prime
Fri Jul 30, 2021 9:21 am
Forum: 8-bit acorn hardware
Topic: 6502 minimum inter-write time
Replies: 4
Views: 166

6502 minimum inter-write time

Hi all, Running at 1MHz such as a stock Atom or a Beeb 1MHz bus, what is the minimum possible time betwween writes to a peripheral register? e.g. for the follwoing code : LDA #$55 STA $8000 STA $8000 I'm assuming it the second write would happen 4 cycles after the first, one for the instruction fetc...
by Prime
Tue Jul 27, 2021 1:03 pm
Forum: 8-bit acorn hardware
Topic: BeebSID circuit....
Replies: 8
Views: 255

Re: BeebSID circuit....

Thanks MartinB, IanS Figured it was something like that I seem to remember a similar circuit on the Electron expansion interfaces for a similar reason. Well it would explain why I'm having problems getting my pi-pico to 1Mhz interface working.....time for some solder and kynar I think..... Cheers. P...
by Prime
Tue Jul 27, 2021 1:00 pm
Forum: 8-bit acorn hardware
Topic: BeebSID circuit....
Replies: 8
Views: 255

Re: BeebSID circuit....

That schematic is misleadingly drawn though: LS02 is a NOR gate but drawn as a NAND. It's not drawn as a NAND, but as a NOR using the DIN symbol . I don't like it, since it's too easily mistaken for a NAND, but it's not actually wrong. And is what you get if you place an LS02 from the 74xx-eu libra...
by Prime
Mon Jul 26, 2021 11:51 pm
Forum: 8-bit acorn hardware
Topic: BeebSID circuit....
Replies: 8
Views: 255

BeebSID circuit....

Hi all,

The BeebSID has a bunch of LS gates, part of which are simply the address decoding.
beebsid.png
But what is IC3 doing?

Cheers.

Phill.
by Prime
Fri Jul 16, 2021 12:01 am
Forum: acorn atom and acorn system series
Topic: Interfacing an Atom to a Raspberry Pi Pico
Replies: 94
Views: 4855

Re: Interfacing an Atom to a Raspberry Pi Pico

An interesting project idea would be to redesign the pico vga board using an RP2040 in place of the pico. It is a bit easier now that JLCPCB stock the chip. jlcpcb.PNG https://twitter.com/JLCPCB/status/1408343801865728002 Possibly, but at the numbers we'd be talking about for Atom (or even Dragon/C...
by Prime
Thu Jul 15, 2021 4:12 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1732
Views: 177850

Re: RGB to HDMI using a Pi Zero and a small CPLD

BUMP! I'm currently powering the RGB2HDMI from an external PSU, as this means it's not dependent on the power from the host computer. However this means that LED D1 is constantly flashing when there is no input signal. Is there a way to disable this, or better still have it flash but time out after ...
by Prime
Sun Jul 04, 2021 7:35 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1732
Views: 177850

Re: RGB to HDMI using a Pi Zero and a small CPLD

I'm currently powering the RGB2HDMI from an external PSU, as this means it's not dependent on the power from the host computer. However this means that LED D1 is constantly flashing when there is no input signal. Is there a way to disable this, or better still have it flash but time out after it's b...
by Prime
Fri Jul 02, 2021 7:52 am
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1732
Views: 177850

Re: RGB to HDMI using a Pi Zero and a small CPLD

I wouldn't have thought that looking for a header for the PiZero would be so difficult. I thought I could chuck the terms into a search engine and come up trumps These are the ones I buy then cut down (I use them for other things in various lengths so buy them in this format as works out the best c...
by Prime
Thu Jul 01, 2021 10:51 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1732
Views: 177850

Re: RGB to HDMI using a Pi Zero and a small CPLD

Right I put both of my boards under my Microscope to check the soldering and found a couple of dodgy solder joints on both boards...... One of them I'd ommitted to solder one of the header pins too :( Having tested one (and also having sorted out my multiple brain farts making up the connecting cabl...
by Prime
Thu Jul 01, 2021 8:12 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1732
Views: 177850

Re: RGB to HDMI using a Pi Zero and a small CPLD

Ok I worked it out (it's actually marked on the board :) ), here's the boot log. pi.log Cheers, Phill. I'm not an expert, but it seems the analog board is not detected... did the four row pins in the analog and main board make good contact? Nope quite correct, no analog board, as I'm just using the...
by Prime
Thu Jul 01, 2021 7:01 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1732
Views: 177850

Re: RGB to HDMI using a Pi Zero and a small CPLD

Ok I worked it out (it's actually marked on the board :) ), here's the boot log.
pi.log
(5.33 KiB) Downloaded 17 times
Cheers,

Phill.
by Prime
Thu Jul 01, 2021 6:19 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1732
Views: 177850

Re: RGB to HDMI using a Pi Zero and a small CPLD

"1920x1080 No sync detected Scaling: Auto (integer/sharp). Profile: BBC_Micro_v10-v20" That profile is one of the legacy ones for the original 3-bit only board. This suggests either the wrong firmware has been programmed, or the Pi is mis-reading the CPLD identifier. Do you have a Pi Seri...
by Prime
Thu Jul 01, 2021 4:47 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1732
Views: 177850

Re: RGB to HDMI using a Pi Zero and a small CPLD

Hi all, I've finally got round to testing the CPLD boards I had built, and the results are that I can't get it working :) I downloaded the latest firmware package and unpacked to a freshlu (fat32) formatted card. Powering on the Pi brought up the CPLD unprogrammed menu and it detected I had a 6/12 b...
by Prime
Fri Jun 25, 2021 9:43 am
Forum: 8-bit acorn hardware
Topic: 6522 question.....
Replies: 2
Views: 213

6522 question.....

Hi All, I'm a little bit confused about the Timer/Counter registers in the 6522, as according to the data sheet some of the latches can be accessed at different locations for the same value? e.g. a write to register 4 will write to the low order latches of Timer 1, but it seems that a write to regis...
by Prime
Thu Jun 24, 2021 1:00 pm
Forum: acorn atom and acorn system series
Topic: Video sync.....
Replies: 2
Views: 191

Video sync.....

Hi all, Am I correct in assuming (from looking at the schematics), that the only way that you could sync to the video on the Atom was from PC7 being wired to the 6847 FS signal? I seem to remember Kees showing me a program that changes colour sets halfway down the screen, am I correct in thinking th...
by Prime
Fri Jun 18, 2021 11:22 pm
Forum: acorn atom and acorn system series
Topic: Atom speed benchmark....
Replies: 21
Views: 593

Atom speed benchmark....

Hi All,

Is there a speed benchmark program for the Atom, that will give a speed rating of some sort?

However it *MUST NOT* require a 6522......

Cheers.

Phill.
by Prime
Mon Jun 14, 2021 9:13 pm
Forum: 8-bit acorn hardware
Topic: What do we think of this?
Replies: 8
Views: 723

Re: What do we think of this?

My other thought, for the Elk, is could it be used to improve memory access speed? That's effectively what the Slogger Turbo & Slogger Master RAM boards did, static RAM thatwas only connected to the CPU and had an 8 bit datapath, so could run at full CPU speed rather than ULA speed**. **Well mo...
by Prime
Fri Jun 11, 2021 6:49 pm
Forum: acorn atom and acorn system series
Topic: Interesting Atom boot screen.......
Replies: 7
Views: 252

Re: Interesting Atom boot screen.......

oss003 wrote:
Fri Jun 11, 2021 6:48 pm
Is it a RPI Pico?
Yeah it's cjm's pi pico board, I've just been working on the firmware for it and the Dragon equivilent.

Cheers.

Phill.
by Prime
Fri Jun 11, 2021 6:48 pm
Forum: acorn atom and acorn system series
Topic: Interesting Atom boot screen.......
Replies: 7
Views: 252

Re: Interesting Atom boot screen.......

Well cjm and hoglet must take most of the credit for the initial idea and implementation (see the pi pico / Atom thread viewtopic.php?f=44&t=21694 . I've just ported it to work on the Dragon and implemented some other facilities.

Cheers.

Phill.
by Prime
Fri Jun 11, 2021 5:35 pm
Forum: acorn atom and acorn system series
Topic: Interesting Atom boot screen.......
Replies: 7
Views: 252

Re: Interesting Atom boot screen.......

oss003 wrote:
Fri Jun 11, 2021 4:50 pm
A Spectrum font?
Nice......
It is......oddly it's not you I expected to spot it :)

But has several other fonts too....

Cheers.

Phill.
by Prime
Fri Jun 11, 2021 4:48 pm
Forum: acorn atom and acorn system series
Topic: Interesting Atom boot screen.......
Replies: 7
Views: 252

Interesting Atom boot screen.......

Check this out.....
P1000849.JPG
Cheers.

Phill.
by Prime
Fri Jun 11, 2021 4:38 pm
Forum: for sale / freebies
Topic: I have 3 x GM25608S-20P - Free - Just P&P
Replies: 8
Views: 368

Re: I have 3 x GM25608S-20P - Free - Just P&P

Thanks for the comments. Still available, if anyone wants them. If not I have a bunch of 8K parts in the same 0.3" package. So, I think for the production run of the Pegasus PCBs I'll add an extra row of holes for the SRAM. If you're clever about it, you can plonk a 300mil DIL package and a 60...
by Prime
Thu Jun 10, 2021 10:36 pm
Forum: other vintage hardware, software and languages
Topic: A brand new Commodore PET kit computer
Replies: 3
Views: 322

Re: A brand new Commodore PET kit computer

It's neat and all, and I can see a lot of work has gone into it.

But for me it's a bit LOLPRICE, especially as I have a real 3032 (Well it says 3008 on the front but It's got 32K now).

Cheers.

Phill.
by Prime
Thu Jun 10, 2021 10:27 pm
Forum: for sale / freebies
Topic: I have 3 x GM25608S-20P - Free - Just P&P
Replies: 8
Views: 368

Re: I have 3 x GM25608S-20P - Free - Just P&P

daveejhitchins wrote:
Thu Jun 10, 2021 6:24 pm
I've absolutely no idea what these are :? (GM25608S-20P)
I googled GM25608S and got this post as the first hit......guess nobody knows what they are.....

I'm guessing memory of some sort, what package are they in?

Cheers.

Phill.
by Prime
Thu Jun 10, 2021 9:39 am
Forum: development tools
Topic: Beebdis symbols
Replies: 6
Views: 452

Re: Beebdis symbols

Hi both,

Would it be possible to provide me with a zip file containing an example of where the bug hits?
Ideally this would contain symbol file, control file and binary (to disassemble).

Cheers.

Phill.
by Prime
Thu Jun 10, 2021 12:14 am
Forum: development tools
Topic: Beebdis symbols
Replies: 6
Views: 452

Re: Beebdis symbols

Hi all,

I'm a little busy at the mo, but will try and find some time to look into this.

@iainfm: There is a stringscan function, it's documented in the doc file on the Github repo.....

Cheers.

Phill.
by Prime
Sun Jun 06, 2021 12:02 am
Forum: off-topic
Topic: KiCad, question.....
Replies: 4
Views: 196

KiCad, question.....

Hi All, I'm awaiting delivery of some of the RGB to HDMI boards. When they arrive I'll have the job of assembling them, to aid me in this it would be advantagous if I could print out the board outline, with just component outline, names and values of the components. I know how to do this in Eagle, b...

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