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Good enough for a Beeb then? :) Somewhat surprisingly, there have been times where a 100MHz scope wasn't quite good enough. Optimising PiTubeDirect is a good example, where each GPU clock cycle saved in critical code shifts the read data timing by 2.5ns. I know what you mean. On my external Tube 65...

Nice find!

good ic 28 pins socket , with good legs Duikkie is talking about "turned pin sockets". This has the advantages duikkie mentions but there is a risk... the turned socket pins are fatter than a chip leg and may damage/bend the spring contacts in the sockets on the BBC. If you remove the socket later ...

I don't have a complaint about the edited tags but the new 'auto draft saved!' which pops up every few seconds now with sliding CSS causing the options/attachments block to 'duck'... repeatedly... every few seconds... is /extremely/ annoying.

leenew wrote: ↑

Mon Jun 18, 2018 9:10 pm

What setup do you have it running on?

A normal issue 7 model B with 8271 disk interface and DFS 1.2. I used two of my sideways RAM modules (available for sale ) to get banks 4&5 as SRAM.
Chris

Michael Brown wrote: ↑

Mon Jun 18, 2018 11:57 am

PS Did you try the Dunjuz RAM game which also loads into banks 4 and 5 (due to the same issue with BeebEm)?

I just tried Dunjunz now from the disc image in your other thread. It loads on a real BBC too. I played a few screens but nothing more.

3) Load it into a BBC with no datacentre, but a sideways RAM board with 2 spare banks (4 and 5) and see if it loads and works correctly as it does under emulation. Seems to load & play. I hit a ball almost 10 yards with a 1 wood. Does it have to be hardcoded to banks 4&5? P.S. Don't own a datacentr...

Depending on the DRAM failure I've seen the data output not being at the same voltage as the working chips. You can see this on a scope.

Try probing the DRAM side of IC14 and see if any of the data traces look different from the other 7. Doing this in 16KB mode a bank at a time makes sense.

Acorn: "QC? Yeah we heard of it."

hoglet wrote: ↑

Wed Jun 13, 2018 6:31 pm

Is there any chance you could upload an example of the instruction stream somewhere?

I know I could easily make up a test one, but it would be fun to develop with the real thing....

I could render 10s or 20s of video into an instruction stream say. I'll PM you a link.

There is the benefit of course that you don't need to care about the address... just reply on any and every Tube read. Perhaps this helps with the low level register requirement? To the first order it needs 2MB/s (120MB/min) to feed the 6502. Is there any DMA that could help - like on the embedded c...

It's a shame it won't run directly from the buffer in the FT232H (in CPU mode) otherwise anyone with a board from eBay would be able to run it on their machine. I had to add some more buffering with extra hardware. No reason why it couldn't be made to run from a pi-tube direct i suppose.

tricky wrote: ↑

Wed Jun 13, 2018 2:23 pm

For the full frame swap, you could just update the pallet (offscreen)

I had that in my list of optimisations I didn't need in the end. Also multiple palette swaps during the frame... again not needed.

Does the forum now enforce SSL? Perhaps the http index has been binned if those URLs are now invalid/redirect and it needs to reindex the site with https URLs...

Witchcraft, I tell you! :D I'm still slightly confused about one detail. The CPU is still only running at 2MHz so, even though you have a perfectly precomputed instruction stream, you've still only got 39936 cycles/frame so can write a maximum of 9984 bytes/frame which is far less than the MODE 0 s...

A mate came over and filmed it on his new fangled smartphone thingy. BBC Tube Bad Apple There are a few moire effects not visible in real life & you can see the hash that the LCD makes of some of the dithering... but it works. If you hear mumbling in the background that is us talking in the other ro...

Lion wrote: ↑

Tue Jun 12, 2018 6:36 pm

Two (broken!) 5¼ drives for US$150.

I've got two broken ones too... the caps leak and corrode the top board. I'll happily let them go for $100

I've ordered one of the cheap boards off ebay, that comes with the ST link, but also one of the nucleo boards from Rapid, as in the past I've found having an official dev board can help when you start out.... I found the "MX Cube" software from the ST website was a help to getting started quickly. ...

Most of the recent commits are for GCC not the 6502 GCC backend. Flibble and I are using the m65x-gcc-virt branch - but some commits back. The changes I made were to the startup files to remove a Commodore 64 BASIC reference - which trashes a BBC BASIC variable. Moving the zero page variables can be...

flibble is using it for his graphical RPG. I use it for my BBC tools dev.

I found that website too while looking for the definitive answer. I've found that TEC and another model Mitsubishi drive I have use 150R. The TEAC FD-55x drives use 330R (specified in documentation). I just wondered if anyone actually knew what was specified for this model originally.

myelin wrote: ↑

Mon Jun 11, 2018 8:02 pm

Note that the STM32F103 (Cortex-M3) chips used in the cheap boards from China are not 5V tolerant.

Based on? You have to read the datasheet to see which IO are FT as some are but not others. The F103 has a dozen or so FT GPIO in the QFP on the cheap boards.

Search STM32F103 on ebay. You can get arduino nano style boards for ~£1.60

I bought an ST Link II programmer too - so cheap I was expecting a knock off but it turned out to be genuine!

Hi,

Does anyone know what value the MF503A/B drives use as a terminator resistor? TEAC manuals specify 330R but I can't find the value Mitsubishi specified.

Chris

The code stream doesn't have to be precomputed... it can be generated on the fly. Small bursts could be used to move sprites for example from a pi or fpga co-pro.

I am sure it will be possible to get a video. Either one here or at another ABUG.

Memory board installed in a A500 6A & configured for the full 2MB. The fly lead goes off to JP2 which is the jumper normally used to select if you want the trapdoor memory to be slow/ranger RAM or chip RAM. The fly lead allows it to provide both types of memory. The Gary adapter is required to get a...

The production version PCBs are in now so I can post some pics of those if anyone is interested?

Tested now and compatible with A500 issue 3, 5 & 6 as well as the A500+

BigEd wrote: ↑

Wed Jun 06, 2018 5:45 pm

Spectacular! Wish I'd been around to see it. Any chance of a video?

I'll see what I can do about a video... my phone camera is low res video unfortunately. I don't have a PC capture card either.

Could the playback have been done bitd with some simple counters and 74 series logic and a large ROM? A counter that increments when a read from the second 16 bytes happens after the previous one being from the first 16 bytes. This would be used to address the ROM for reads for the first 16 bytes. ...

Edit: YouTube link - https://www.youtube.com/watch?v=D_ta5QxBSMk Motivation: I was talking with Kieran last year at the Leicester ABUG about 2nd processor acceleration for games & the limit of what is practicable. The ultimate I suggested was to execute code directly from the Tube memory window FFE0...