Search found 220 matches

by SteveBagley
Sat Jan 11, 2020 7:55 pm
Forum: other vintage computer hardware, software and games
Topic: ZX Spectrum next... Anybody backing ?
Replies: 165
Views: 16439

Re: ZX Spectrum next... Anybody backing ?

Presumably there's nothing stopping an Acorn Second Processor being attached to the ZX Spectrum anyway. Hardware wise, the TUBE is all implemented in the second processor by the ULA, the TUBE connector is just contains part of the address bus and the data bus exactly the same signals as provided on ...
by SteveBagley
Sat Jan 11, 2020 12:05 am
Forum: hardware
Topic: Acorn ROM/RAM Podule Manager
Replies: 10
Views: 253

Re: Acorn ROM/RAM Podule Manager

Have just tested it with the BBC View ROM 'inserted' as well as the manager ROM, and I'm able to access that and run it in the 6502 Emulator :)

Steve
by SteveBagley
Fri Jan 10, 2020 11:05 pm
Forum: hardware
Topic: Acorn ROM/RAM Podule Manager
Replies: 10
Views: 253

Re: Acorn ROM/RAM Podule Manager

Have you seen the circuit diagram on the last page of the Acorn manual? (my ROM image was from the Acorn version). http://chrisacorns.computinghistory.org.uk/docs/Acorn/Manuals/Acorn_ROM_Podule_Guide.pdf It doesn't give detail of the GAL, but it should give you some clues. Yep, definitely useful --...
by SteveBagley
Fri Jan 10, 2020 10:27 pm
Forum: hardware
Topic: Acorn ROM/RAM Podule Manager
Replies: 10
Views: 253

Re: Acorn ROM/RAM Podule Manager

Yea -- I'm attempting to write an extension for Arculator to emulate it (mainly to get used to the API before implementing some more interesting podules. Just trying to reverse engineer how the podule maps the ROM's into the podule address space at the moment, other than that it looks reasonably str...
by SteveBagley
Fri Jan 10, 2020 11:40 am
Forum: general
Topic: Today I received.....
Replies: 5599
Views: 465133

Re: Today I received.....

An A3000 motherboard… http://wotan.computer/temp/a3000_mb.jpg Then just need to sort out a case for it (and fix the CMOS battery)… Well, almost three years later, I've finally obtained a case, keyboard and PSU for the motherboard -- just need to find out how much damage the battery did (I neutralis...
by SteveBagley
Thu Jan 09, 2020 10:33 pm
Forum: hardware
Topic: Acorn ROM/RAM Podule Manager
Replies: 10
Views: 253

Re: Acorn ROM/RAM Podule Manager

Yep, looks great thanks.

Steve
by SteveBagley
Thu Jan 09, 2020 8:42 pm
Forum: hardware
Topic: Acorn ROM/RAM Podule Manager
Replies: 10
Views: 253

Acorn ROM/RAM Podule Manager

Does anyone know if there is a dump of the Manager ROM found on Acorn's (or Computer Concepts) ROM/RAM podule available online or is anyone able to make one?

Steve
by SteveBagley
Thu Jan 09, 2020 1:57 pm
Forum: hardware
Topic: Emulating (or obtaining!) an ARM Evaluation System
Replies: 10
Views: 407

Re: Emulating (or obtaining!) an ARM Evaluation System

What I don't want to do is spend a lot of time prototyping on an emulated system that's similar to the ARM1 but different enough that when I finally come to try it on actual hardware it doesn't work. Hence my question being about the accuracy of existing emulation. How much changed between the ARM1...
by SteveBagley
Mon Jan 06, 2020 8:35 pm
Forum: acorn atom and system
Topic: Acorn System/Atom Econet
Replies: 13
Views: 497

Re: Acorn System/Atom Econet

The System Econet server software has been posted on stardot in the past, although I suspect you've already found that.

Steve
by SteveBagley
Mon Jan 06, 2020 8:16 am
Forum: general
Topic: Graphics Display from the Late 1960s or early 1970s
Replies: 4
Views: 253

Re: Graphics Display from the Late 1960s or early 1970s

the YouTUBE link suggests the text read ‘Computer controlled display' — Google image searching on that led (indirectly)to the image on this page,

http://www.chilton-computing.org.uk/ca/ ... s/p005.htm

Which describes it as an IDI display.

Steve
by SteveBagley
Sun Jan 05, 2020 2:44 pm
Forum: software
Topic: RISCiX Netboot
Replies: 5
Views: 530

Re: RISCiX Netboot

Did the R225 truly exist? I know it was advertised but, like the A410 I’m not sure I have ever seen someone saying they had one The RISCiX cloned thread suggests they did -- ajw99uk mentions there might be one at TNMoC and crj seems to have analysed the modules on the podule. I guess the difference...
by SteveBagley
Fri Jan 03, 2020 4:08 pm
Forum: software
Topic: RISCiX Netboot
Replies: 5
Views: 530

Re: RISCiX Netboot

A bit more playing around and I've managed to extract the NFS module (attached -- there also appears to be an application called 'nfsboot' in the pboot file which I still need to extract). The pboot file has an interesting structure... It seems to be made up of 512 byte blocks, where the first 8 byt...
by SteveBagley
Fri Jan 03, 2020 12:55 pm
Forum: software
Topic: RISCiX Netboot
Replies: 5
Views: 530

RISCiX Netboot

I've been poking around RISCiX over Christmas and came across an interesting file lurking that might go someway to explaining how RISCiX can be net booted (e.g. on the R225, but it'd also be fun to get it to netboot off a modern UNIX system). Over in the RISCiX cloned thread, crj said As I recall, i...
by SteveBagley
Mon Dec 23, 2019 8:29 pm
Forum: hardware
Topic: A4000 strange io problem
Replies: 9
Views: 284

Re: A4000 strange io problem

Jaydr wrote:
Mon Dec 23, 2019 6:57 pm
Hdd is still identifying as 4: so no access as yet
Have you tried a delete-power on to reset the CMOS? Also, make sure you are enabling an IDE hard disc rather than just a Hard disc (the latter aren't supported on the A4000).

Steve
by SteveBagley
Fri Dec 06, 2019 11:16 pm
Forum: general
Topic: Remarkable videos recently posted on Youtube
Replies: 308
Views: 36997

Re: Remarkable videos recently posted on Youtube

Was at the Aussie Floyd (Pink Floyd tribute band) gig this evening and they used this video to back their performance of ‘Welcome to the Machine’. There’s a few Acorn/BBC references in it :-)

https://youtu.be/hZPKtx8f8Iw

Thought people might enjoy it…

Steve
by SteveBagley
Thu Dec 05, 2019 12:35 am
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 99
Views: 5102

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Indeed, it could well be that the mux is for RAS and CAS multiplexing. Although, why a dual 4 way mux? There's at least three output values it needs to feed A8 on the memory chips: 0 (during refresh cycles, the data sheet seems to suggest you still only need to cycle A0-A7 to refresh the DRAM chips...
by SteveBagley
Wed Dec 04, 2019 7:04 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 99
Views: 5102

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Hmm, I'm not sure if IC33 is a 74LS138. If it is, then you have one of its outputs (pin 11, /O4) connected to the output of a 74LS27 (IC31?, pin 8 ) which doesn't seem to make any sense… If IC33 is a 74LS138 then I wouldn't be surprised if it is being used to decode the instruction's addressing mode...
by SteveBagley
Tue Nov 26, 2019 12:54 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 99
Views: 5102

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Presumably, the additional memory decoding (i.e. which bank of memory is accessed) is triggered by certain page accesses and opcodes. The CPU just sees it all as memory in its 64KB space and isn't really aware that the additional memory has been accessed. From the description above, it seems to be ...
by SteveBagley
Fri Oct 25, 2019 7:27 am
Forum: software: other
Topic: Short and sweet prime numbers in Basic
Replies: 24
Views: 1125

Re: Short and sweet prime numbers in Basic

Variant on Dave's contribution which uses bits instead of bytes for sieve elements, thus allowing primes up to 100000 to be calculated. Crunched for illegibility speed less slowness. 60P%=2:REPEATPRINTP%:IFP%+P%<M%FORI%=P%+P%TOM%STEPP%:J%=I%DIV8:S%?J%=S%?J%ORT%?(I%AND7):NEXT 70REPEATP%=P%+1:UNTIL(S...
by SteveBagley
Tue Oct 22, 2019 12:38 am
Forum: hardware
Topic: Very dead A3000 (now very much alive)
Replies: 20
Views: 999

Re: Very dead A3000

The A3000 motherboard lets you connect up an A310 style motherboard if you cut a couple links and solder in the correct socket — I used a PS2 extension cable cut in half to get the socket to attach.

Might be worth trying that to get a working keyboard if you have one to hand?

Steve
by SteveBagley
Wed Oct 02, 2019 1:02 pm
Forum: hardware
Topic: A680s
Replies: 19
Views: 2508

Re: A680s

Did any of these ever get repaired?

Steve
by SteveBagley
Sat Sep 28, 2019 9:00 pm
Forum: for sale / freebies
Topic: Apple Mac Plus 1MB
Replies: 1
Views: 284

Re: Apple Mac Plus 1MB

If anyone does buy it (they are great machines), don’t forget to replace the RIFA capacitors on the analog board!

Steve
by SteveBagley
Fri Sep 27, 2019 9:55 am
Forum: hardware
Topic: A4 Laptop - replacement electrolytic capacitors and CMOS battery
Replies: 21
Views: 1147

Re: A4 Laptop - replacement electrolytic capacitors and CMOS battery

Picked up a box of these to recap the A4: https://www.amazon.co.uk/gp/product/B07NK9SKNJ/ (440-piece SMD electrolytic capacitor kit) Looks like it has the right sizes and values, and it's cheaper than buying the parts individually from RS... Expect more updates this weekend! Please take lots of pho...
by SteveBagley
Fri Sep 20, 2019 1:25 pm
Forum: general
Topic: Acorn Discord group?
Replies: 10
Views: 569

Re: Acorn Discord group?

trixster wrote:
Fri Sep 20, 2019 9:28 am
Think of it as modern IRC.
What's wrong with just using IRC (or XMPP for that matter)?

Steve
by SteveBagley
Sat Sep 14, 2019 9:08 am
Forum: off-topic
Topic: Capturing interlaced / 50Hz video
Replies: 37
Views: 1215

Re: Capturing interlaced / 50Hz video

dominicbeesley wrote:
Tue Sep 10, 2019 3:28 pm
You do if it contains a RobC nula!
True -- although then you could just capture the data input into the nULA and implement a nULA emulator in software :)

Steve
by SteveBagley
Tue Sep 10, 2019 2:40 pm
Forum: off-topic
Topic: Capturing interlaced / 50Hz video
Replies: 37
Views: 1215

Re: Capturing interlaced / 50Hz video

dominicbeesley wrote:
Tue Sep 10, 2019 1:37 pm
the blocker on this is that most of the good ADC's seem to be either end-of line or very expensive.
You don't need an ADC for the Beeb -- the RGB output is TTL level. I successfully used a cheap USB logic analyser to capture the video in the past.

Steve
by SteveBagley
Thu Aug 15, 2019 8:06 am
Forum: hardware
Topic: Noisy Mode 7 display
Replies: 42
Views: 1977

Re: Noisy Mode 7 display

Thinking it might be a ram issue, I typed in one of the simpler ram test issues I found in the forum (the one which reads from &3000 to &8000 and looks for non-zero values), I found that it reports 255 at &3000 and every 256 bytes thereafter. Which seems to support the theory. That’s an odd error… ...
by SteveBagley
Thu Aug 01, 2019 10:21 pm
Forum: off-topic
Topic: Toshiba TV Haunted!
Replies: 21
Views: 1188

Re: Toshiba TV Haunted!

I suspect a modern TV doesn't actually switch itself off properly unless you disconnect it from the wall -- so doing a first-time install probably forced the TV to reboot fully and hence fix the problem.

Steve
by SteveBagley
Thu Aug 01, 2019 10:14 am
Forum: off-topic
Topic: Toshiba TV Haunted!
Replies: 21
Views: 1188

Re: Toshiba TV Haunted!

The TV is still under warranty, only bought in February 2019, but regrettably the receipt has been mislaid. I'd try taking it back to the shop anyway -- presumably you paid for it using a credit/debit card which should be enough for them to find the transaction on their system if you take the credi...
by SteveBagley
Sun Jul 28, 2019 10:48 pm
Forum: hardware
Topic: A310 restoration
Replies: 74
Views: 3355

Re: A310 restoration

Given… It's a standard ARM2, with what looks like an IFEL 2Mb upgrade and RISC OS 3. And the symptoms… I've replaced the 3 tantalums, but powering it up (with a known working PSU) the power LED lights and a brief flash of the keyboard lights, but no other signs of life - no video signal or any flopp...