Search found 361 matches

by dominicbeesley
Tue Sep 19, 2017 10:49 pm
Forum: hardware
Topic: Master CMOS checksum
Replies: 0
Views: 39

Master CMOS checksum

I've been trying to figure out how the Master 128 checksums its CMOS settings. All I've found so far is this which has been very helpful but doesn't mention the actual checksum http://beebwiki.mdfs.net/CMOS_configuration_RAM_allocation So I'm guessing the checksum is at location 50, does anyone know...
by dominicbeesley
Sun Sep 17, 2017 3:20 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4189

Re: 6809 experiments

I've got a bit of the way in speccing out the new version, including throwing together more VHDL test cases (I want to work out feasibility of a blitter / DMA chip before I start laying out boards). As an aide memoire I've been sketching it out on paper (red = 5V, blue = 3.3V), it seems to concentra...
by dominicbeesley
Wed Sep 13, 2017 3:35 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4189

Re: 6809 experiments

Thanks Nigel, I'd not spotted that one. I think I'll go with the 8877s then!

I'll have to have a pour over the datasheets with a bottle of red one evening and work out if it will do ADFS to 720/800k

D
by dominicbeesley
Wed Sep 13, 2017 1:23 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4189

Re: 6809 experiments

I have a question about disc controller chips. Would the MB8877a work with BBC micro discs (I have a number of these form Lez Anderson, thanks Lez!). If not I'll probably crib something from the Master and use a WD1770? I think on my next board design I'm going to leave a couple of headers to allow ...
by dominicbeesley
Tue Sep 12, 2017 11:36 pm
Forum: hardware
Topic: Desoldering components
Replies: 10
Views: 237

Re: Desoldering components

grobda wrote:I use a duratool desolder station - zd-915, seems to be a slightly older model than the current one.


I'm gonna get me one of those, I just saw a video of it and it looks perfect. I got a desolder/sucker thing off ebay a few weeks ago and one word...garbage!

D
by dominicbeesley
Tue Sep 12, 2017 6:50 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4189

Re: 6809 experiments

Captain Pugwash now works! So I'm going to give BASIC development a bit of a rest and concentrate on the next version of the motherboard now. This will take some thought as I want to give it plenty of thought and try and get it more or less right first time as the PCBs will not be cheap! I've also p...
by dominicbeesley
Tue Sep 12, 2017 2:27 pm
Forum: hardware
Topic: Troubleshooting my latest BBC B
Replies: 70
Views: 863

Re: Troubleshooting my latest BBC B

If your logic analyser has 16 channels then could you hook it up to the address lines and see if it hits the clear routine at D9E7-DA00 on cold reset and skips it on warm? Then we can stop worrying about system via/RSTA.
by dominicbeesley
Tue Sep 12, 2017 12:10 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4189

Re: 6809 experiments

That and the fact that the carry flag is a borrow flag has lead to many interesting errors.

I'm now nearly there with captain pugwash! It works without envelopes but sounds like a cliched pile up of American police cars at the end of any 1970's road movie with envelopes...

D
by dominicbeesley
Tue Sep 12, 2017 11:37 am
Forum: hardware
Topic: Beeb FPGA
Replies: 310
Views: 17833

Re: Beeb FPGA

That's great but there are very few *monitors* that would work. Increasing the number of pixels on a line does not increase the number of times it is scanned per second, that would just up the pixel clock. see the spec I posted: Minimum horz freq 30kHz (i.e. Interlace will not work *1) Minimum vert ...
by dominicbeesley
Tue Sep 12, 2017 11:22 am
Forum: hardware
Topic: Troubleshooting my latest BBC B
Replies: 70
Views: 863

Re: Troubleshooting my latest BBC B

How many channels does your Analyser have, if its >=24 worth hooking up to the data and address lines and trying to suss out where it gets to in the reset? If not, the main difference is that the whole of RAM is cleared if it's a hard reset. So the machine may be hanging if the system VIA is NOT res...
by dominicbeesley
Mon Sep 11, 2017 1:15 pm
Forum: hardware
Topic: Troubleshooting my latest BBC B
Replies: 70
Views: 863

Re: Troubleshooting my latest BBC B

Rough location marked on the bbc schematics...it took me a while to find a few weeks ago when I discovered the same thing!
by dominicbeesley
Mon Sep 11, 2017 12:11 pm
Forum: hardware
Topic: Troubleshooting my latest BBC B
Replies: 70
Views: 863

Re: Troubleshooting my latest BBC B

It's meant to do that, the system via only resets on power up (simple diode/resistor/capacitor to +5V), this is how the beeb detects a warm vs cold start. First try swapping system and user vias whilst cleaning the pins ( a gentle scrape off of oxide with a knife and a squirt of servisol or similar)...
by dominicbeesley
Mon Sep 11, 2017 12:24 am
Forum: hardware
Topic: BBC Model B takes up smoking
Replies: 22
Views: 455

Re: BBC Model B takes up smoking

why "the short term" ? don't really need them, they where to stop interference with old TV tune in & the FM radio dial. but since we have digiTV and radio is full of adverts, no one listens to it now anyways :lol: Caps : caps.jpg it's usually the big one that goes pop, easy fix if you...
by dominicbeesley
Sun Sep 10, 2017 11:21 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4189

Re: 6809 experiments

Yes, JGH and I have been busy in the background sorting out the APIs, I've made a whole lot of changes to BASIC and the 6809 MOS to try and harmonise between 6809tube, Matchbox/PI and my "machine"+MOS (I need to think of a name for it!). The BASIC is getting there but I keep uncovering nig...
by dominicbeesley
Sun Sep 10, 2017 4:45 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4189

Re: 6809 experiments

Milestones achieved: - basic FS working (*CAT, *LOAD, LOAD, CHAIN) - CLOCKSP now runs to completion! BASIC is getting close to usable now. There is a horrible bug hidden somewhere in the floating point routines, once that is fixed, I'm going to stop concentrating on BASIC for a while and put it to o...
by dominicbeesley
Fri Sep 08, 2017 2:36 pm
Forum: hardware
Topic: Beeb FPGA
Replies: 310
Views: 17833

Re: Beeb FPGA

Nope, Take this one at random (first one I found) http://www.dell.com/downloads/emea/products/snp/E207WFP_Monitor.pdf Most tellies say they do 576i/50, all my monitors wont! I've no idea why, I find it particularly annoying! I suspect its to stop us all from using (cheap) monitors instead of more ex...
by dominicbeesley
Fri Sep 08, 2017 1:54 pm
Forum: hardware
Topic: New 65C02/W65C816 copro
Replies: 65
Views: 2168

Re: New 65C02/W65C816 copro

You did set up all your timing constraints in your FPGA code didn't you? You didn't, nor do I usually for "slow" stuff but I found the 65816 to be a real bugger for fast timing even though its running at only 8MHz on my board it will happily respond to *very* short glitches, and as you've ...
by dominicbeesley
Wed Sep 06, 2017 2:07 pm
Forum: hardware
Topic: New 65C02/W65C816 copro
Replies: 65
Views: 2168

Re: New 65C02/W65C816 copro

Sounds good though room/pads for a ZIF socket for a ROM is always welcome! I've gone for a mix of through hole and smd on my latest creations, the advantage of SMD are cost availability etc but hackability is still far easier with through hole chips....I'm still glad I had the sense to put the 245 b...
by dominicbeesley
Wed Sep 06, 2017 10:32 am
Forum: hardware
Topic: New 65C02/W65C816 copro
Replies: 65
Views: 2168

Re: New 65C02/W65C816 copro

I've had fakes (capacitors, ICs) from the big distributors, they get duped too! I even scrapped my old car when I got bored of replacing the HEI module only to find out that the parts distributor had been duped and were selling crap modules. I have however, recently bought a number of chips from Ali...
by dominicbeesley
Tue Sep 05, 2017 12:33 pm
Forum: hardware
Topic: NuLA demos
Replies: 80
Views: 2781

Re: NuLA demos

WOW! =D>
by dominicbeesley
Tue Sep 05, 2017 8:48 am
Forum: hardware
Topic: NuLA demos
Replies: 80
Views: 2781

Re: NuLA demos

Nice on Rob, do you have an ssd?

D
by dominicbeesley
Mon Sep 04, 2017 3:12 pm
Forum: off-topic
Topic: Fine Ales
Replies: 18
Views: 377

Re: Fine Ales

Not bad, a touch on the pale side for me but a nice pint nonetheless. I used to have that every week at the pub quiz. He now serves the Cross Bay Beers, Halo and Sunset that aren't bad but I prefer the nightfall http://crossbaybrewery.co.uk/index.php/our-beers/nightfall This talk is all making me in...
by dominicbeesley
Mon Sep 04, 2017 2:45 pm
Forum: hardware
Topic: Retro Cassette recorders
Replies: 12
Views: 370

Re: Retro Cassette recorders

Tapes aren't a bad storage medium, if a little fiddly. I have plenty of 35+ year old tapes that were carried around in damp school bags, knocked around, partially demagnetised but still I can get information off them. The cheaper tapes seem to survive the best. Though the ICL mainframe boot up tapes...
by dominicbeesley
Mon Sep 04, 2017 2:43 pm
Forum: off-topic
Topic: Fine Ales
Replies: 18
Views: 377

Re: Fine Ales

I know all that, I just don't like the fact that that seems to be _all_ you can get now in pubs that 10 years ago had a nice selection of dark brown through to pale beers of various strengths. Not all two pints then fall over juice. Choice is good, so long as its not a choice between 50 things, whic...
by dominicbeesley
Mon Sep 04, 2017 2:12 pm
Forum: off-topic
Topic: Fine Ales
Replies: 18
Views: 377

Re: Retro Cassette recorders

It certainly is, I wasn't dismissing IPA per-se just the over-strength cats pee that is sold these days. A nice pint of flowers, green kings, etc lovely. American style craft nonsense...awful eight pints of that and I feel sick! :wink: Can't get a decent gallon of week tasteless beautiful beer these...
by dominicbeesley
Mon Sep 04, 2017 10:56 am
Forum: hardware
Topic: Beeb FPGA
Replies: 310
Views: 17833

Re: Beeb FPGA

HDMI can be coaxed out of the de0 nano so should be doable from the de1. I got it working with my BeebFPGA I did a few years ago I think I started with something from here http://hamsterworks.co.nz/mediawiki/index.php/Minimal_HDMI but can't quite find the exact project I cribbed. I seem to recall th...
by dominicbeesley
Mon Sep 04, 2017 10:47 am
Forum: hardware
Topic: Retro Cassette recorders
Replies: 12
Views: 370

Re: Retro Cassette recorders

I found that most players could be coaxed into working so long as they output a sufficient (not too loud though) level. The main things that caused one player to work and another not were dirty or mis-aligned tape heads. Some q-tips, a bottle of IPA (iso-propyl-alochol, not the horrid over flavoured...
by dominicbeesley
Fri Sep 01, 2017 2:50 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4189

Re: 6809 experiments

The filing system thing has taken a _lot_ longer than I expected but has forced me to address a lot of the stuff that was missing in the MOS and to get my head into the Vinculum / FTDI / USB thing. It's nowhere near finished but *. now works!

D
by dominicbeesley
Tue Aug 29, 2017 11:51 am
Forum: hardware
Topic: 'JIM' based extra 64K RAM
Replies: 17
Views: 738

Re: 'JIM' based extra 64K RAM

What JGH said!
by dominicbeesley
Tue Aug 29, 2017 11:48 am
Forum: hardware
Topic: New 65C02/W65C816 copro
Replies: 65
Views: 2168

Re: New 65C02/W65C816 copro

ooh! looks good

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