Search found 1704 matches

by BigEd
Mon Feb 19, 2018 4:40 pm
Forum: projects
Topic: Making reasonable progress with a Sudoku solver
Replies: 75
Views: 2519

Re: Making reasonable progress with a Sudoku solver

It's an interesting area! My own approach to tackling a sudoku problem sometimes leaves me stuck, even when there is a solution - so "hard" is certainly relative to tactics employed.

Edit: oops, meant to link here.
by BigEd
Mon Feb 19, 2018 3:52 pm
Forum: projects
Topic: Making reasonable progress with a Sudoku solver
Replies: 75
Views: 2519

Re: Making reasonable progress with a Sudoku solver

There are a few difficult sudoko challenges here , and this one took 108.65s on jsbeeb: . . . | . . . | . . 8 . . 3 | . . . | 4 . . . 9 . | . 2 . | . 6 . -------+-------+------- . . . | . 7 9 | . . . . . . | . 6 1 | 2 . . . 6 . | 5 . 2 | . 7 . -------+-------+------- . . 8 | . . . | 5 . . . 1 . | . ...
by BigEd
Mon Feb 19, 2018 12:07 pm
Forum: projects
Topic: Making reasonable progress with a Sudoku solver
Replies: 75
Views: 2519

Re: Making reasonable progress with a Sudoku solver

many thanks!

("L" to load T.HARDEST or T.17CELLS)
by BigEd
Mon Feb 19, 2018 10:39 am
Forum: projects
Topic: Making reasonable progress with a Sudoku solver
Replies: 75
Views: 2519

Re: Making reasonable progress with a Sudoku solver

This looks very nice to me! Could a clever person please cook up a link to jsbeeb which directly loads and boots the SSD?
by BigEd
Sun Feb 18, 2018 9:28 am
Forum: acorn atom
Topic: Case for your Atom from back in the day
Replies: 4
Views: 268

Re: Case for your Atom from back in the day

Ah, that could be it - in the case of a chargeback the customer wins and the retailer loses, and that might be too much to bear.
by BigEd
Sat Feb 17, 2018 9:22 pm
Forum: off-topic
Topic: Romance is dead
Replies: 6
Views: 439

Re: Romance is dead

I wonder what did it? The news of an Issue 1 selling on ebay???

(Previous high score was in July 2016, when PiTubeDirect was featured on Hackaday)
by BigEd
Sat Feb 17, 2018 7:39 pm
Forum: acorn atom
Topic: Case for your Atom from back in the day
Replies: 4
Views: 268

Re: Case for your Atom from back in the day

Maybe there was very little profit in the Beeb so the retailer's credit card charge was too much to bear? Do we know what price Acorn charged the retailer?
by BigEd
Sat Feb 17, 2018 6:16 pm
Forum: general
Topic: Acorn Computer (System 1 as it’s known now) Review
Replies: 6
Views: 312

Re: Acorn Computer (System 1 as it’s known now) Review

Nice - thanks! I wonder if I might have read that back in the day. There's an 80 page version of the UPPER CASE user manual here http://chrisacorns.computinghistory.org.uk/docs/Acorn/Manuals/Acorn_System1UserManual.pdf and the technical manual here http://chrisacorns.computinghistory.org.uk/docs/Aco...
by BigEd
Fri Feb 16, 2018 5:36 pm
Forum: for sale / freebies
Topic: sundry modems collect-only: Stoke on Trent
Replies: 0
Views: 297

sundry modems collect-only: Stoke on Trent

just in case there's interest, Anthony Rogers says:
Does any one in the Stoke on Trent (UK) area want a mixed box of modems? Mixed types and speeds. [Collect only]


(Probably not acorn-specific, so mods, please delete if that's the right thing to do.)
by BigEd
Fri Feb 16, 2018 10:09 am
Forum: hardware
Topic: Music 5000 - sound generation
Replies: 12
Views: 510

Re: Music 5000 - sound generation

I wouldn't expect to see it used as a sound peripheral for a game. There a quote from Nick "Orlando" Pelling about using the Music 500 in Firetrack 2 in the Lost & Found section of the Stairway to Hell site. He basically says the same thing - it just takes up too much of the CPU's tim...
by BigEd
Fri Feb 16, 2018 9:27 am
Forum: hardware
Topic: Music 5000 - sound generation
Replies: 12
Views: 510

Re: Music 5000 - sound generation

Interesting idea - I'm sure it would be technically possible, but I don't know what BeebSID and BeebOPL actually do.
by BigEd
Thu Feb 15, 2018 9:04 pm
Forum: hardware
Topic: Music 5000 - sound generation
Replies: 12
Views: 510

Re: Music 5000 - sound generation

I think the primary description is a wavetable synthesiser, which means each voice can be an arbitrary waveform. That doesn't make it a sampling synth - the samples are far too short to qualify, usually they'd be a single cycle of a waveform. The "ring modulator" capability seems very basi...
by BigEd
Thu Feb 15, 2018 5:51 am
Forum: hardware
Topic: Music 5000 - sound generation
Replies: 12
Views: 510

Re: Music 5000 - sound generation

Hoglet and I investigated the Music 5000 design, finding it ingenious and wonderful, and I wrote some notes over here: http://forum.6502.org/viewtopic.php?f=4&t=4436 - high quality phase-accumulating wavetable synthesiser, 16 note polyphonic. - low part count, all TTL with two RAMs, plus a DAC. ...
by BigEd
Wed Feb 14, 2018 6:39 pm
Forum: programming
Topic: ADFS Format
Replies: 25
Views: 1663

Re: ADFS Format

I'm not sure there's any wear involved when writing to a floppy. There will be wear according to how much time the disk rotates under the (loaded) head, but because the disk keeps spinning for a while after each access, that might be regarded as per-track wear rather than per-sector wear, and would ...
by BigEd
Thu Feb 08, 2018 7:44 pm
Forum: other vintage computer hardware, software and games
Topic: Apple II Super Serial Card Rebuild
Replies: 19
Views: 598

Re: Schematic notation...

I would say links you can cut (bow ties) or pad-pairs you can short (droids)
by BigEd
Thu Feb 08, 2018 4:34 pm
Forum: off-topic
Topic: Why did CISC prevail?
Replies: 21
Views: 840

Re: Why did CISC prevail?

(I found myself reading this presentation by Richard Grisenthwaite of ARM, from 2009 I think, on the evolution of ARM offerings and the difficulties of designing a successful architecture.) While SPARC and POWER might still have a little life in them, and even MIPS too , I think we should look to RI...
by BigEd
Sat Feb 03, 2018 6:12 pm
Forum: hardware
Topic: R65C02 in a Beeb
Replies: 51
Views: 1564

Re: R65C02 in a Beeb

It's not totally surprising that the CMOS part is a bit marginal, especially with the unusually fast edge rates, but it's a major surprise to me that it would affect SBC and nothing else!

An excellent adventure.
by BigEd
Sat Feb 03, 2018 8:59 am
Forum: hardware
Topic: R65C02 in a Beeb
Replies: 51
Views: 1564

Re: R65C02 in a Beeb

That is odd. If SBC is tested first, it might be worth reversing that to see if ADC ever fails. If ADC is already tested first and never fails, that's a datapoint.
by BigEd
Fri Feb 02, 2018 10:37 pm
Forum: hardware
Topic: R65C02 in a Beeb
Replies: 51
Views: 1564

Re: R65C02 in a Beeb

Hmm, and that's a different SBC from last time... Is SBC tested before ADC? Is it always an SBC which fails? I wonder if there's some pattern sensitivity such that the E9 opcode is more problematic than the 69 opcode?? I'm supposing - not sure why - that the opcode is affecting the reliability of re...
by BigEd
Fri Feb 02, 2018 6:40 pm
Forum: hardware
Topic: R65C02 in a Beeb
Replies: 51
Views: 1564

Re: R65C02 in a Beeb

It feels like the PHP is perhaps pushing the wrong value of C - as opposed to C being wrong as the result of SBC. If you put in a

Code: Select all

   BCC skip
   NOP
skip:
just before the PHP, you'd see whether C is set or not at that point. Is that useful to know? I'm not sure.
by BigEd
Fri Feb 02, 2018 4:49 pm
Forum: software: other
Topic: Conway's Game of Life for Atom, Beeb, Elk?
Replies: 70
Views: 5025

Re: Conway's Game of Life for Atom, Beeb, Elk?

This is somewhat off-topic but I thought it might be of interest: Faster LIAR - Life In A Register It's for 32 bit platforms, so good for ARM based machines perhaps. Code here , I think. There are also 32 bit tricks in Isaac Kuo's JavaScript life - see this post in the thread over on 6502.org. I hav...
by BigEd
Fri Feb 02, 2018 8:29 am
Forum: hardware
Topic: Minimal Tube 6502decode bus snoop with FTDI USB
Replies: 60
Views: 2149

Re: Minimal Tube 6502decode bus snoop with FTDI USB

Rather impressive! How does it do at cold start, when it doesn't know anything about the machine state?
by BigEd
Thu Feb 01, 2018 10:51 pm
Forum: wanted
Topic: Lx9pro fpga copro
Replies: 23
Views: 834

Re: Lx9pro fpga copro

That's great to hear Rob. Do you know what ClockSp reports as the equivalent speed? JGH's blog says, I think, that the 20MHz PDP-11 in the matchbox clocks in as a 25MHz 6502 equivalent.
by BigEd
Thu Feb 01, 2018 9:14 am
Forum: off-topic
Topic: Thermistor, washing machine and hair dryer
Replies: 11
Views: 462

Re: Thermistor, washing machine and hair dryer

They are not always called 6502s - but you look at the datasheets and see the instruction count or the registers and addressing modes and the clues are there. GeneralPlus, formerly SunPlus, made a number of microcontrollers with 6502 cores inside - most famously, inside the HP 35s scientific calcula...
by BigEd
Wed Jan 31, 2018 3:35 pm
Forum: wanted
Topic: Lx9pro fpga copro
Replies: 23
Views: 834

Re: Lx9pro fpga copro

(Except only the matchbox has the pdp11 mode.)
by BigEd
Mon Jan 29, 2018 4:57 pm
Forum: software: new games
Topic: New Release: Retro Software's WHITE LIGHT by Sarah Walker
Replies: 68
Views: 4720

Re: New Release: Retro Software's WHITE LIGHT by Sarah Walker

Difficult to judge the age of an elf: Galadriel is 7000 years old, for example.
But Sarah has volunteered her age over in What is the average age on here??
by BigEd
Mon Jan 29, 2018 4:45 pm
Forum: off-topic
Topic: 40
Replies: 27
Views: 1142

Re: 40

I'm certainly hoping the Spectrum Next can be coaxed into Atom and Beeb behaviours.
by BigEd
Thu Jan 25, 2018 8:00 pm
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 41
Views: 1946

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

Great project, great writeup!
by BigEd
Thu Jan 25, 2018 3:41 pm
Forum: hardware
Topic: Question about B and Master
Replies: 18
Views: 615

Re: Question about B and Master

From memory, some of the Level 9 adventures (like Ingrid's Back) will use the extra RAM in the B+ and Master but I don't think they use sideways RAM on the B. That's what I'd expect: the B+ and Master can hide the screen memory, leaving much more room for programs in the main 32k RAM - in fact, the...
by BigEd
Wed Jan 24, 2018 12:50 pm
Forum: off-topic
Topic: 40
Replies: 27
Views: 1142

Re: 40

(This is Ben Heck's build, with a laser-cut Beeb-like case, on YouTube.)