Search found 611 matches

by IanB
Sun May 10, 2020 4:07 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

After several attempts, with fingers boiled on the microswitches, I thought of changing the internal switch (OS1 - Color / mono) of the Apple IIe PAL and setting it to mono: the color appeared clear and bright! Thanks for testing it. (I did say you would have to change to mono!) I noticed anyway th...
by IanB
Sun May 10, 2020 10:43 am
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

aotta wrote:
Sun May 10, 2020 10:34 am
Ian, i got an error in unzipping the file, it seems corrupted, can you check it?
Thank you for sharing!
Try this:
Artifact Colours v2.zip
(120.15 KiB) Downloaded 13 times
by IanB
Sun May 10, 2020 2:22 am
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

Thank you for the info, and waiting for your progress in both challenges! Here's an experimental version with artifact colours: [deleted] First make sure you have the latest release installed then unzip the above, overwrite the kernel.img file with this version and copy the two Apple II profiles in...
by IanB
Sat May 09, 2020 11:58 pm
Forum: 8-bit acorn hardware
Topic: Pi1MHz future supported devices
Replies: 15
Views: 950

Re: Pi1MHz future supported devices

Do you think a Prisma 3 emulation would fit into your 1Mhz framework now that there is a nearly finished MAME / ACRTC emulation:
viewtopic.php?f=3&t=15650&start=30
by IanB
Thu May 07, 2020 3:33 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

For example, i'm testing a Sega SC-3000 getting the Y,R-Y and B-Y signal for the analog board, but can't get right colours. I wired Y to both sync and Green (2 & 4), but i'm afraid i'm not connected to the right pads. The connection to both 2 & 4 is correct for Y but you would also need a user defi...
by IanB
Wed May 06, 2020 2:47 am
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Pernod wrote:
Wed May 06, 2020 2:24 am
I had the exact same realisation a few minutes ago, implementing now.
Sorry it's actually (SAR << 1) | (SDA >> 1) as there is one overlapping bit as you only need the 2 middle bits from the SDA.
In theory the overlapping bit should be the same value in both registers.
by IanB
Wed May 06, 2020 2:21 am
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

This is interesting, so in theory the base screen should only be addressed to 8 pixels accuracy, but I'm seeing it being addressed to 2 pixels accuracy. Maybe the ROM is reading some video register that's returning the wrong value, causing the ROM to increment the start address incorrectly? Need to...
by IanB
Tue May 05, 2020 4:07 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

I'm still seeing the SDA being incremented four times 2,4,6,8 between the memory start address word being updated, so don't see how I can shift by 4 pixels when there's only 2 pixels per start address. I don't see how the numbers can be used to produce the desired effect, could be awhile figuring t...
by IanB
Mon May 04, 2020 11:49 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

I'm still looking at background horizontal smooth scrolling, specifically how to apply the Start Dot Address (SDA). In the CIRCUS animation the SDA increments from 1 to 15 in steps of 2, so 1, 3, 5, 7, 9, B, D, F whilst the Start Address Register (SAR) increments by a word every four SDA increments...
by IanB
Fri May 01, 2020 5:18 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

A photo of the whole board would be useful. Here's a photo: Prisma2_internals.jpg Also larger as the forum shrinks images: Prisma2_internals_large.zip You can see it uses a 14.7456 Mhz crystal so that is probably the frequency or a multiple of that frequency generated on the Prisma 3 by it's PLL. T...
by IanB
Fri May 01, 2020 3:21 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

It works fine, with a little DAC adjustment, i've a dk'tronics's case for my rgbtohd cable: Thanks for confirming your 48K Spectrum works. Do you know what issue your board is? (It's been tried on Issue 2 and 3 so far). I did some test with my Apples too... the IIe clone with monochrome output work...
by IanB
Fri May 01, 2020 12:30 am
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Do I have a test animation for it? No, I haven't found one yet. Any Prisma 2 info would be very useful anytime soon, whilst I ponder on other issues. I've posted the Prisma 2 manual, the later Prisma 3 manual and the 3+ / Archimedes supplement in archive submissions. https://stardot.org.uk/forums/v...
by IanB
Thu Apr 30, 2020 11:32 pm
Forum: archive submissions
Topic: Prisma 3 issue 1.00 manual and 3+ / Archimedes supplement
Replies: 0
Views: 327

Prisma 3 issue 1.00 manual and 3+ / Archimedes supplement

The Prisma 3 was a 256 colour graphics adapter for the BBC micro. This is the Prisma 3 manual issue 1.00 June 1988. (The previous Prisma 3 manual posted was issue 0.1 August 1987) Prisma_3_manual (Issue 1.00).zip This is the supplementary manual covering the Prisma 3+ and the Archimedes interface (I...
by IanB
Thu Apr 30, 2020 10:19 pm
Forum: archive submissions
Topic: Prisma 2 graphics adapter manual
Replies: 1
Views: 278

Prisma 2 graphics adapter manual

Prisma 2 graphics adapter manual:

This was the 16 colour predecessor to the 256 colour Prisma 3
by IanB
Wed Apr 29, 2020 10:29 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

Got some new PCBs today: pcbs.jpg They are a drilling template for the case with full size holes, a PC 6 bit buffer, a general purpose 6 bit buffer and an 8 bit buffer. The complete family of interfaces: interfaces.jpg Left to right: Analog interface 3 bit TTL buffer PC 9 way TTL MDA/CGA/EGA buffer ...
by IanB
Wed Apr 29, 2020 12:09 am
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

Thank Ian for the zxspectrum wiring, I have some spare joystick adapter I can use for cabling the analog boards, another line in my to do list! Here's the connections to the edge connector: Pin 1(GND) to Edge conn 14B (GND) Pin 2 (Sync) to Edge conn 16B (Y) Pin 3 (Blue/U) to Edge conn 18B (U) Pin 4...
by IanB
Tue Apr 28, 2020 11:08 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

As suggested, i simply reduced the max horizontal capture size, and solved with this profile: Looks great, thanks for the profile. The Spectrum 48K is connected as follows to the 6 way IDC cable Pin 1(GND) to ULA pin 40 (GND) Pin 2 (Sync) to ULA pin 17 (Y) Pin 3 (Blue/U) to ULA pin 15 (U) Pin 4 (Gr...
by IanB
Tue Apr 28, 2020 2:16 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Using the two versions of MagicWand256 I notice the mention of 900GX Series. Was the 900GX a separate machine in the range, or just an upgraded 900 Series? Should I be adding a 900GX machine to include the Prisma 3+? The 900 Manager ROM is GX too, does this mean there was also a standard 900 Manage...
by IanB
Mon Apr 27, 2020 11:12 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

Today are arrived the 5 analog boards I've ordered from China, already populated. They cost me a fortune, but seems they made a good work, and I hope they works: They look nicely made: Here is one of mine which shows the placement of the 6 way IDC header: front.jpg back.jpg Also note the two pins P...
by IanB
Mon Apr 27, 2020 7:29 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Yes, I can select tools and draw, but not for long. After a few clicks I can still move the pointer but buttons stop responding and also can't Escape to the other menu. Not sure what to look at for that. The pointer is interrupt driven so that will carry on working when the foreground task is hung ...
by IanB
Mon Apr 27, 2020 1:59 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

With a copro both will hang, so definitely an issue there somewhere. Also after loading a picture or animation my cursor indicates waiting zZZ, so am unable to continue. Any idea what it's waiting for? The software actually runs in the I/O processor even with the CoPro enabled so not sure why that ...
by IanB
Sun Apr 26, 2020 11:31 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

So what should each machine comprise of? 800 Series: Master 128, 65C102 internal copro, Prisma 2, Mouse (AMX compatible), Acorn Winchester 900 Series: Master 128, 65C102 internal copro, Prisma 3, Mouse (AMX compatible), Acorn Winchester Were the ROMs used in cartridge slots or in place of SWR? ROMs...
by IanB
Sun Apr 26, 2020 9:06 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

hoglet wrote:
Sun Apr 26, 2020 6:41 pm
So I guess your "new" CPLD wasn't actually blank, and was driving pins 39/40.
Can you get the CPLD to output 1.6v? Those pins weren't conflicting with any other outputs unless there were multiple shorts as well.
by IanB
Sun Apr 26, 2020 8:18 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Thanks, it's like having a new toy to play with :) I found a couple more programs: 1. A racing game. This was used on another childrens program with in studio contestants: racing.jpg This one is a little problematic as it was hooked up to a 1Mhz bus I/O device for multiple controllers (beebex?), on...
by IanB
Sun Apr 26, 2020 5:01 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

Just a quick update. I had chance this weekend to isolate pins 39 and 40. This did the trick. Cursor now behaving and CPLD programmed through pi fine. Everything now works flawlessly. Thank you so much for the suggestions. I got there in the end with a little help! The whole family are loving it. G...
by IanB
Sun Apr 26, 2020 4:49 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Now all software that I currently have seems to be working, albeit with some minor graphic issues due to window delay trim. Here is the updated image: scsi0.zip You should be able to boot to a menu which should give you options for all the different versions of Magic Image and Magic Wand. I have in...
by IanB
Sat Apr 25, 2020 1:17 am
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Getting better every day! I also have background delay trim in there which I believe makes the HAFOC jungle screenshots perfectly aligned with your photos, though the 3 doors are now offset. But loading TRAIN6 results in the image being shifted right 3 pixels, losing the right hand side of the image...
by IanB
Thu Apr 23, 2020 6:42 pm
Forum: 8-bit acorn hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 77
Views: 5786

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Does the Prisma ever display a cursor, in either graphic or text modes? I'd guess not as it seems to be using the CUD1, CUD2 outputs for blanking. Don't think it ever had a hardware cursor. Would I be right in thinking it uses the DISP1, DISP2, and DRAW output lines to trigger the bank switches? Do...
by IanB
Mon Apr 20, 2020 10:21 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

Resistor values are correct both visually identified and with a multimeter. I removed them and still have 1.6v on the corresponding gpio pins. Guess I'm going to have to look into this deeper...... Thanks for everybody's help this far! The soldering on pins 25 and 29 of the GPIO header looks a bit ...
by IanB
Mon Apr 20, 2020 8:57 pm
Forum: 8-bit acorn hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 1239
Views: 98856

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

wjnuk wrote:
Mon Apr 20, 2020 8:45 pm
Resistor values are correct both visually identified and with a multimeter. I removed them and still have 1.6v on the corresponding gpio pins. Guess I'm going to have to look into this deeper...... Thanks for everybody's help this far!
Can you post a hires closeup photo of the board?

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