Search found 725 matches

by dp11
Sun Feb 11, 2018 7:25 pm
Forum: hardware
Topic: Mega Games Cartridge (MGC) MK II Hardware Development
Replies: 25
Views: 711

Re: Mega Games Cartridge (MGC) MK II Development

Does MISO need a pull resistor?
by dp11
Sun Feb 11, 2018 6:52 pm
Forum: hardware
Topic: Mega Games Cartridge (MGC) MK II Hardware Development
Replies: 25
Views: 711

Re: Mega Games Cartridge (MGC) MK II Development

I would probably try and get nRST on to the GSR pin of the CPLD if possible
by dp11
Sun Feb 04, 2018 12:34 am
Forum: hardware
Topic: 2 Faulty Beebs
Replies: 89
Views: 1550

Re: 2 Faulty Beebs

At least one cad system uses /R/S/T which renders as RST with a bar across the top. I've never come across ¬RST but have used RSTB in the past. Many early CAD systems didn't allow non text as net names. If they did when you came to export information and read it into another system it usually ended ...
by dp11
Sat Feb 03, 2018 11:48 am
Forum: hardware
Topic: R65C02 in a Beeb
Replies: 51
Views: 1182

Re: R65C02 in a Beeb

try tieing pin 38 directly high e.g. to pin 8.
by dp11
Sat Feb 03, 2018 10:36 am
Forum: hardware
Topic: R65C02 in a Beeb
Replies: 51
Views: 1182

Re: R65C02 in a Beeb

Maybe worth adding a little more decoupling. Also might be worth looking at the clock signal .
by dp11
Fri Feb 02, 2018 6:18 pm
Forum: hardware
Topic: R65C02 in a Beeb
Replies: 51
Views: 1182

Re: R65C02 in a Beeb

Can't say why but It might be worth looking at the SO pin 38?
by dp11
Mon Jan 29, 2018 12:10 am
Forum: general
Topic: Recovering Tapes perished pressure pads
Replies: 12
Views: 277

Re: Recovering Tapes perished pressure pads

I don't know of a dual capstan deck that engages both pinch rollers at the same time.
by dp11
Fri Jan 26, 2018 10:30 am
Forum: off-topic
Topic: help by explaining schematic
Replies: 25
Views: 711

Re: schematic riddle

I would need a higher resolution image to be sure what the brown thing is. The off board connection from the brown thing ( bottom of the image ) is broken.
by dp11
Thu Jan 25, 2018 3:36 pm
Forum: off-topic
Topic: help by explaining schematic
Replies: 25
Views: 711

Re: schematic riddle

What is the application ? post us a photo of the board.
by dp11
Sun Jan 07, 2018 11:27 pm
Forum: projects
Topic: New game - tube type thingy
Replies: 36
Views: 1632

Re: New game - tube type thingy

On the master can you use a number of swr bank so that you have 70k of loads and writes to the screen buffer so no x or y indexes are used?

On the 6502 pitubedirect the is also banked ram available giving you 2MBytes
by dp11
Thu Jan 04, 2018 11:38 pm
Forum: off-topic
Topic: CPU International Crisis - Are We All Doomed?
Replies: 18
Views: 729

Re: CPU International Crisis - Are We All Doomed?

The issue is about one process reading data that it shouldn't have access to. If you allow random people to log in to your pi then they could read all of the memory which might have say passwords in it. If you run a Web browser on your pi and go to a website with special java script on it then it ca...
by dp11
Sat Dec 30, 2017 9:02 pm
Forum: hardware
Topic: Playing with the SAA5050
Replies: 14
Views: 871

Re: Playing with the SAA5050

On the beeb the latch on the data bus can also be cleared with TTXVDU , so the values loaded is &40.
by dp11
Tue Dec 26, 2017 1:40 pm
Forum: off-topic
Topic: network guru and electrician wanted
Replies: 18
Views: 1085

Re: network guru and electrician wanted

No argument with you say .

But "Singles" usually refer to single insulated cables by electricians. Google image search for the term "singles" and see how many images are returned for the cable you define to be singles. You may also go over the IET forum .
by dp11
Tue Dec 26, 2017 8:46 am
Forum: off-topic
Topic: network guru and electrician wanted
Replies: 18
Views: 1085

Re: network guru and electrician wanted

I'm not sure your definition of "singles" is the same as most electricians. http://www.pewelectrical.com/cable-and-accessories/wiring-cables/15mm-singles-stranded-6491x.htm https://www.click4electrics.co.uk/blue-singles-c-57_124_125/ http://www.nvq2356.com/unit-305/
by dp11
Mon Dec 25, 2017 7:29 pm
Forum: off-topic
Topic: network guru and electrician wanted
Replies: 18
Views: 1085

Re: network guru and electrician wanted

Before anyone else put loose singles under floors you should consult BS7671 Table 4A1 as I don't think they are really permitted. "Singles" usually refers to a cable with only one layer of insulations or protection. Also any addition needs testing and a Minor works Certificate filled out. ...
by dp11
Sun Dec 24, 2017 5:16 pm
Forum: off-topic
Topic: network guru and electrician wanted
Replies: 18
Views: 1085

Re: network guru and electrician wanted

I don't know about your situation , but you might need this : http://www.meteorelectrical.com/cables- ... -coil.html
by dp11
Mon Dec 18, 2017 10:12 am
Forum: off-topic
Topic: pcb boards with lanes on ebay ?
Replies: 3
Views: 162

Re: pcb boards with lanes on ebay ?

tradename Veroboard, but everyone calls it veroboard
by dp11
Fri Dec 15, 2017 11:22 am
Forum: hardware
Topic: BBC Master screen interference PiTube direct
Replies: 57
Views: 1634

Re: BBC Master screen interference PiTube direct

I've been thinking about this a bit more. I would like the level shifters to always have nOE tied low. The DIR pin then only during the correct phase of the clock and if nTUBE is low and Read is high will DIR be set such that it drives the Masters Databus. The reason for this is that the databus can...
by dp11
Wed Dec 13, 2017 9:42 pm
Forum: hardware
Topic: BBC Master screen interference PiTube direct
Replies: 57
Views: 1634

Re: BBC Master screen interference PiTube direct

So I think we might need to gate nTube with phi2 to drive oe of the level converter.

My level converter is passive resistors and diodes I will do some tests to see if the problem occurs with this version.
by dp11
Wed Dec 13, 2017 7:04 pm
Forum: hardware
Topic: BBC Master screen interference PiTube direct
Replies: 57
Views: 1634

Re: BBC Master screen interference PiTube direct

Would you mind testing different tube delays and see if there is any difference? I'll try and look at the code over the weekend.
by dp11
Wed Dec 13, 2017 1:29 pm
Forum: hardware
Topic: BBC Master screen interference PiTube direct
Replies: 57
Views: 1634

Re: BBC Master screen interference PiTube direct

That could be possible as the master data bus only wants the data bus driven for half a cycle. PiTubeDirect is likely to drive the databus for more than half a cycle. Still puzzled by the audible noise unless there is a low of current flowing on the data bus.
by dp11
Wed Dec 13, 2017 1:08 pm
Forum: hardware
Topic: BBC Master screen interference PiTube direct
Replies: 57
Views: 1634

Re: BBC Master screen interference PiTube direct

As the noise is audible, I suspect we need some low frequency decoupling. The on board level shifter caps will only be good at high frequency. I suspect added something between 100uf and 1000uF might help. It might also be a sign the 5v caps in the PSU are starting to fail.
by dp11
Tue Dec 12, 2017 10:36 pm
Forum: hardware
Topic: RISC OS 3.20 ROM's?
Replies: 120
Views: 4206

Re: RISC OS 3.20 ROM's?

Just a thought. If space is really tight I wonder if you can find any common sub expressions across all the modules.
by dp11
Mon Dec 11, 2017 9:13 pm
Forum: hardware
Topic: Beeb FPGA port to Spectrum Next
Replies: 40
Views: 1423

Re: Beeb FPGA port to Spectrum Next

A Pi zero will beat any FPGA core.
by dp11
Sun Dec 10, 2017 6:33 pm
Forum: hardware
Topic: how to do ? raspberry pi 2 and beeb b lost it
Replies: 57
Views: 1189

Re: how to do ? raspberry pi 2 and beeb b lost it

Make sure all the ground pins on the Tube and the Pi are connected. Have you added any decoupling ?
by dp11
Sun Dec 10, 2017 5:44 pm
Forum: hardware
Topic: Only the Break key works on Keyboard
Replies: 15
Views: 549

Re: Only the Break key works on Keyboard

I think pin 4 or pin 12 on the cable being broken might cause the keys to stop working.
by dp11
Sun Dec 10, 2017 4:32 pm
Forum: hardware
Topic: how to do ? raspberry pi 2 and beeb b lost it
Replies: 57
Views: 1189

Re: how to do ? raspberry pi 2 and beeb b lost it

Any SD card will be fine.

Just plug pi and level shifter together and into Beeb. Insert SDCARD and turn the beeb on.
by dp11
Sun Dec 10, 2017 4:18 pm
Forum: software: classic games
Topic: Stryker's Run for the Master
Replies: 30
Views: 1476

Re: Stryker's Run for the Master

Master has an audio output.
by dp11
Sat Dec 09, 2017 9:01 pm
Forum: hardware
Topic: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)
Replies: 1021
Views: 82135

Re: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)

If you are just going to use pi zeros ( of either type) then you can just set the frequency to 1000MHz.
by dp11
Sat Dec 09, 2017 8:54 pm
Forum: hardware
Topic: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)
Replies: 1021
Views: 82135

Re: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)

Do you have a Pizero or PizeroW ?

If you have a ZeroW then in the config.txt you will need to set the speed to 1000MHz