Search found 1892 matches

by BigEd
Mon Jul 16, 2018 3:43 pm
Forum: hardware
Topic: Tube ULA Reverse Engineering
Replies: 128
Views: 15067

Re: Tube ULA Reverse Engineering

Thanks!
by BigEd
Mon Jul 16, 2018 2:10 pm
Forum: acorn atom
Topic: Building an Acorn System 1
Replies: 2
Views: 100

Re: Building an Acorn System 1

Great project!
by BigEd
Sun Jul 15, 2018 10:40 am
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 243
Views: 8061

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

Just a thought - if we line-doubled to x1080 so the GPU is always down-scaling in the Y direction, is that any better? (And, is there time to do it...)
by BigEd
Sun Jul 15, 2018 10:11 am
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 243
Views: 8061

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

I think you've said previously, Dave, that there's not much time left for the Pi's ARM CPU to do much if any image processing and still keep up with the frame rate. And while the GPU is surely capable of sophisticated rescaling, there's no documentation for a baremetal program to make use of. Is the...
by BigEd
Sat Jul 14, 2018 10:54 am
Forum: general
Topic: "Outline specification for the BBC MICROCOMPUTER system"
Replies: 203
Views: 16256

Re: "Outline specification for the BBC MICROCOMPUTER system"

In 2014 David Allen gave a talk at TNMoC which covers the genesis of the BBC Micro proposal and the selection process. Start at about the 15min mark if you're impatient, or the 18min mark if you are really impatient. But perhaps the 12min mark is a good place for a little context - it helps to under...
by BigEd
Sat Jul 14, 2018 10:33 am
Forum: hardware
Topic: Wanted: Second Processor dimensions for 3D printing
Replies: 6
Views: 209

Re: Wanted: Second Processor dimensions for 3D printing

It would be great if you would share your work, once you get there - even if it takes ages. In the future, there will be even fewer bits of kit on ebay, but printers will be larger, faster, and cheaper. And we'll all wear silver suits.
by BigEd
Sat Jul 14, 2018 9:03 am
Forum: hardware
Topic: Wanted: Second Processor dimensions for 3D printing
Replies: 6
Views: 209

Re: BBC Micro collection starts again

Just realised a great labour-saving factoid: the second processor is very much the same shape as the Beeb. So once you have the width measurement, you can measure a Model B for the rest.
by BigEd
Sat Jul 14, 2018 7:42 am
Forum: hardware
Topic: Wanted: Second Processor dimensions for 3D printing
Replies: 6
Views: 209

Re: BBC Micro collection starts again

I can take amateur measurements of a Z80 copro I have. Are you seeking great accuracy and fidelity? Do you want to know radius of all the rounded edges and so on? I have a ruler, but not a micrometer. The service manual gives only the very basic bounding box: 3.6 Outside dimensions Height 72mm Width...
by BigEd
Fri Jul 13, 2018 9:35 am
Forum: software: other
Topic: IRATA.online - a PLATO-like online space for retrocomputing
Replies: 0
Views: 69

IRATA.online - a PLATO-like online space for retrocomputing

If you like retro online services, this might be up your street. Especially if you like multiuser online systems with device-independent text and graphics. IRATA.online.png Especially if you fancy a multiplayer dogfight game over the internet using an 8-bit computer as a terminal. Although you'd hav...
by BigEd
Wed Jul 11, 2018 9:40 pm
Forum: for sale / freebies
Topic: PiTubeDirect signalconverter for BBC Micro
Replies: 136
Views: 12088

Re: PiTubeDirect signalconverter for BBC Micro

Is it a nice fast SD card you're using, and has it been freshly formatted with the official formatter before you put the files on? That might help. See
viewtopic.php?p=187771#p187771
by BigEd
Tue Jul 10, 2018 10:10 am
Forum: general
Topic: Beeb Spotting
Replies: 27
Views: 3110

Re: Beeb Spotting

Not a Beeb, but an Archimedes 3010 and a RISC PC on show at the Vintage Computer Festival East recently:
https://youtu.be/pmkNds5wHkc?t=5m13s
by BigEd
Mon Jul 09, 2018 8:30 pm
Forum: programming
Topic: BASIC FOR loops
Replies: 15
Views: 298

Re: BASIC FOR loops

I'm surprised - I thought it was an official feature to be able to bale out of an inner loop by resuming an outer loop. p273 of the user guide (pdf) : If a variable is given after NEXT then the computer will ‘pop’ other FOR...NEXT loops off the ‘stack’ until it finds a matching variable. If none is ...
by BigEd
Sun Jul 08, 2018 4:58 pm
Forum: upcoming and recent events & exhibitions
Topic: Vintage Computer Fest - Mountain View, California - Aug 4-5
Replies: 1
Views: 67

Re: Vintage Computer Fest - Mountain View, California - Aug 4-5

Clever logo! Name badges and other identifying marks are a very good idea so people recognise each other and start chatting.
by BigEd
Sat Jul 07, 2018 6:52 pm
Forum: general
Topic: BBC releases computer history archive
Replies: 90
Views: 1967

Re: BBC releases computer history archive

I'm going to guess it's the serial ULA... probably wrong but it looks a bit like it has a regular 9-bit structure in there. The nature of a ULA is that it has a very regular array of transistors, and all the lower levels of the chip, and it's just the final top metal layer which is customised for a ...
by BigEd
Sat Jul 07, 2018 3:44 pm
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 243
Views: 8061

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

Very neat indeed!
by BigEd
Sat Jul 07, 2018 8:17 am
Forum: software: other
Topic: Close-by primes - a benchmark (collection)
Replies: 0
Views: 88

Close-by primes - a benchmark (collection)

If you like benchmarks, and prime numbers, you might like this thread over on 6502.org: slightly OT: a simple Benchmark As the thread progresses, you'll notice it encompasses the comparisons of back-in-the-day machines, but also their respective Basics, and also various faster ways to compute the sa...
by BigEd
Fri Jul 06, 2018 8:11 pm
Forum: off-topic
Topic: How to make a battery motor run at different speeds?
Replies: 9
Views: 209

Re: How to make a battery motor run at different speeds?

I think your best bet is gears, or better yet a pulley. Let the motor spin fast, spinning a small pulley, and take a rubber band to a big pulley. I think adjusting the voltage is likely to be too difficult: the motor is likely to stall.
by BigEd
Thu Jul 05, 2018 8:40 pm
Forum: wanted
Topic: Wanted: Acorn machine
Replies: 10
Views: 455

Re: Wanted: Acorn machine

Are you still in the UK? I'd hope there was a way to get a machine to you before you take off...
by BigEd
Thu Jul 05, 2018 5:05 pm
Forum: hardware
Topic: New 65C02/W65C816 copro
Replies: 82
Views: 5725

Re: New 65C02/W65C816 copro

I think Dave (hoglet) tried once to get a clock signal derived from the host's 2MHz but because of cycle-stretching couldn't get the PLL to lock. But part of the job of the Tube ULA (or the HDL equivalent) is to allow the second processor's clock to be completely independent of the hosts, no? Edit: ...
by BigEd
Thu Jul 05, 2018 4:53 pm
Forum: wanted
Topic: Wanted: Acorn machine
Replies: 10
Views: 455

Re: Wanted: Acorn machine

Did you manage to find a machine?
by BigEd
Thu Jul 05, 2018 2:29 pm
Forum: hardware
Topic: New 65C02/W65C816 copro
Replies: 82
Views: 5725

Re: New 65C02/W65C816 copro

How are you doing the clocking? Perhaps using the FPGA's PLL to make a clock? In which case you've got fine-grained control. No need to swap crystals!

Edit: tweak
by BigEd
Thu Jul 05, 2018 12:00 pm
Forum: hardware
Topic: Tube ULA Reverse Engineering
Replies: 128
Views: 15067

Re: Tube ULA Reverse Engineering

It'd be great to have another open source implementation!
by BigEd
Thu Jul 05, 2018 11:59 am
Forum: hardware
Topic: New 65C02/W65C816 copro
Replies: 82
Views: 5725

Re: New 65C02/W65C816 copro

How's this project going? Looks like it could be the fastest physical CPU on the block (FPGAs not counting in this case.)
by BigEd
Thu Jul 05, 2018 9:31 am
Forum: other vintage computer hardware, software and games
Topic: Elan Enterprise
Replies: 9
Views: 315

Re: Elan Enterprise

Some pinouts:
http://ep.homeserver.hu/Dokumentacio/Ko ... inout.html

Some schematics:
http://web.archive.org/web/199802052305 ... chema.html

Edit: I notice Lisp and Forth ROMs can be found...
by BigEd
Wed Jul 04, 2018 9:43 pm
Forum: other vintage computer hardware, software and games
Topic: Elan Enterprise
Replies: 9
Views: 315

Re: Elan Enterprise

I don't know of it first-hand but it seems a very impressive machine! Lots of info, an emulator or two, and many demos here: http://ep.lgb.hu/ (as you may well already know!) Shouldn't be too hard to rig up a ROM cart for it? That might be easiest, unless perhaps the serial port is easier. Found som...
by BigEd
Wed Jul 04, 2018 12:31 pm
Forum: hardware
Topic: Tube ULA Reverse Engineering
Replies: 128
Views: 15067

Re: Tube ULA Reverse Engineering

IIRC, the only other source of Tube info that we had back in 2009/10 was Yellow Pig's site: http://www.cowsarenotpurple.co.uk/bbccomputer/master512/tube.html (Looks like we started musing about a Tube remake in March or April 2009, and published in 2010. This thread was a very early hint about feasi...
by BigEd
Tue Jul 03, 2018 1:11 pm
Forum: general
Topic: BBC releases computer history archive
Replies: 90
Views: 1967

Re: BBC releases computer history archive

Quite a few interesting bits of info in this 1986 programme: Micro Live Series 3 Episode 1 - Amstrad's new PC cheaper than other clones - Sugar tells software companies to drop prices and sell more copies to make more money - IBM's profits drop by a billion per quarter due to clones - Sir Clive reck...
by BigEd
Tue Jul 03, 2018 7:59 am
Forum: hardware
Topic: Tube ULA Reverse Engineering
Replies: 128
Views: 15067

Re: Tube ULA Reverse Engineering

Welcome to the forum, Gordon! And I do hope you can get some results out of image processing - the checkplot image isn't totally straightforward, but is (I think) more amenable to automatic analysis than the chip photos. Perhaps one day the chip photos will also be within scope! The Tube ULA and Ele...
by BigEd
Mon Jul 02, 2018 9:43 pm
Forum: hardware
Topic: Tube ULA Reverse Engineering
Replies: 128
Views: 15067

Re: Tube ULA Reverse Engineering

I've found that I still have a copy in Dropbox, which can be downloaded from this page: https://www.dropbox.com/s/faxztegtiei333d/Tube-design.png?dl=0 (It might prompt you to sign up but I think you can just cancel that dialogue.) Edit: please acknowledge Steve Furber in any derivative work. He pres...