Search found 66 matches

by ChrisO
Fri Apr 19, 2019 9:38 am
Forum: acorn atom and acorn system series
Topic: Simple mod for 3.5" Floppy Drives on an 8271 ?
Replies: 3
Views: 711

Re: Simple mod for 3.5" Floppy Drives on an 8271 ?

Yes I have looked at Sprow's page, his solution is to modify the drive by adding a Microchip PIC to reinsert the 'missing' index pulses, an alternative approach is JG Harston's patched DFS 1.21 which essentially ignores the drive not ready error. I thought I'd try fixing the underlying problem which...
by ChrisO
Wed Apr 17, 2019 8:22 pm
Forum: acorn atom and acorn system series
Topic: Simple mod for 3.5" Floppy Drives on an 8271 ?
Replies: 3
Views: 711

Simple mod for 3.5" Floppy Drives on an 8271 ?

Having got 5.25" PC drives working on my System computer the next thing to try is a 3.5" drive. There is of course a problem when using these drives with an 8271 controller. Anyway I plugged a Sony MPF920 drive in to the Beeb and it works with small files but as soon as you try saving anyt...
by ChrisO
Mon Apr 15, 2019 8:16 pm
Forum: acorn atom and acorn system series
Topic: Using PC Floppy Drives ?
Replies: 6
Views: 1017

Re: Using PC Floppy Drives ? (Fixed)

Thanks all for the replies. Of course you wouldn't expect to be able to read beyond track 0 on a 40T formatted disk on an 80T drive my brain wasn't in gear when I made the original posting ! Anyway I think its fixed thanks to Kazzie's 3rd posting with the link to the image of the jumper settings, I ...
by ChrisO
Sun Apr 14, 2019 10:32 am
Forum: acorn atom and acorn system series
Topic: Using PC Floppy Drives ?
Replies: 6
Views: 1017

Using PC Floppy Drives ?

I thought I'd got a PC Floppy drive working with my System computer a while ago but that doesn't seem to be the case. Its a Teac FD-55GFR which is an 80 track double sided drive. I've now connected it to my BBC in order to try and figure out whats wrong (8271 floppy disk controller, 2nd 40t drive wi...
by ChrisO
Sat Mar 16, 2019 11:08 am
Forum: acorn atom and acorn system series
Topic: System and BBC Disk Compatability ?
Replies: 7
Views: 949

Re: System and BBC Disk Compatability ?

Sorted ! The problem was the Watford DFS on the BBC. This morning I found an old Viglen Utilities disc which has format on it, using this to format a disc it is recognised and works on the System computer so at last I have a working System 3 :D. I've also managed to get an 80 track PC style floppy (...
by ChrisO
Fri Mar 15, 2019 7:44 pm
Forum: acorn atom and acorn system series
Topic: System and BBC Disk Compatability ?
Replies: 7
Views: 949

Re: System and BBC Disk Compatability ?

A bit more info - looks like the problem is with the BBC using longer addresses ? If I INFO a file on the System 3 I get: 1900 8023 C1B78 C5B (load address, execution address, length, start sector) the same thing on the BBC gives: FF1900 FF8023 001B78 05B My BBC has Watford Electronics DFS 1.42 on i...
by ChrisO
Fri Mar 15, 2019 7:28 pm
Forum: acorn atom and acorn system series
Topic: System and BBC Disk Compatability ?
Replies: 7
Views: 949

Re: System and BBC Disk Compatability ?

Sadly its not that I knew to change the directory (qualifier in System speak) from $.

I'm getting a Disk error 18 whenever I try to access a file ?
by ChrisO
Fri Mar 15, 2019 4:03 pm
Forum: acorn atom and acorn system series
Topic: System and BBC Disk Compatability ?
Replies: 7
Views: 949

System and BBC Disk Compatability ?

I'm trying to get my System 3 upgrade working but I'm stuck because I don't have a format disc for it ? It will read the catalogue off a BBC formated disc but files will not load. I know the underlaying format of the System, Atom and BBC disc is the same but is there some subtlety that stops a BBC d...
by ChrisO
Fri Feb 22, 2019 8:15 am
Forum: acorn atom and acorn system series
Topic: A Website dedicated to the Acorn System Computers
Replies: 42
Views: 4370

Re: A Website dedicated to the Acorn System Computers

We're up again, now at www.theoddys.com/acorn :D

I've added some more info to the PROM Programmer, including software, that'll be of interest to those building System 2's and wanting to programme 74S571's though its a bit chicken and egg as you'll need a System 2 to build a System 1.

Chris
by ChrisO
Mon Feb 18, 2019 5:18 pm
Forum: acorn atom and acorn system series
Topic: A Website dedicated to the Acorn System Computers
Replies: 42
Views: 4370

Re: A Website dedicated to the Acorn System Computers

Oh dear - it was good whilst it lasted !, I hadn't appreciated that plusnet also had a 250MB daily bandwidth limit which really doesn't allow for much at all.

I'll look into alternative web hosting and hopefully be back up and running again shortly.

Chris
by ChrisO
Sun Feb 17, 2019 4:21 pm
Forum: acorn atom and acorn system series
Topic: A Website dedicated to the Acorn System Computers
Replies: 42
Views: 4370

Re: A Website dedicated to the Acorn System Computers

Thanks for your comments Kazzie, I have made some changes to reflect them.

Chris
by ChrisO
Sun Feb 17, 2019 10:36 am
Forum: acorn atom and acorn system series
Topic: A Website dedicated to the Acorn System Computers
Replies: 42
Views: 4370

Re: A Website dedicated to the Acorn System Computers

Holding a tape up to the screen it looks like it would take a System 4 type rack (assuming 19" wide). I'm afraid adding hovering pop-ups etc is well out of my league, I wouldn't know where to start. At some point I'll add photo's of each board, though I'm limited to 250MB with plusnet and curre...
by ChrisO
Sun Feb 17, 2019 10:31 am
Forum: acorn atom and acorn system series
Topic: A Website dedicated to the Acorn System Computers
Replies: 42
Views: 4370

Re: A Website dedicated to the Acorn System Computers

I originally put 'home' links on but then thought because the contents page on the left was always there they weren’t necessary but I hadn't thought about going straight to a subpage. I'll put the links back again !

thanks
Chris
by ChrisO
Sat Feb 16, 2019 5:11 pm
Forum: acorn atom and acorn system series
Topic: A Website dedicated to the Acorn System Computers
Replies: 42
Views: 4370

A Website dedicated to the Acorn System Computers

At last I have more or less finished my website for the Acorn System Computers: www.theoddys.com/acorn (new location) Please have a look, any errors or omissions let me know and I'll try and fix them. There's more to follow, a bit more scanning to do and I'm working on my System 3. Perhaps in conjun...
by ChrisO
Sat Jan 26, 2019 9:06 pm
Forum: development tools
Topic: ca65 .list on off
Replies: 0
Views: 800

ca65 .list on off

I'm using .if .endif to select conditional blocks of code. This does the job but in the listing output the blocks of code that have not been assembled are still shown. I've used .list on/off to switch the listing on for the 'active' blocks only but annoyingly you can see the .list on off instruction...
by ChrisO
Wed Nov 28, 2018 6:30 pm
Forum: acorn atom and acorn system series
Topic: System 2 COS VDU Configuration
Replies: 4
Views: 802

Re: System 2 COS VDU Configuration

Thank you all for the replies, I can now get on and finish the COS review. I'm planning on setting up a website for all the info I have, spent the weekend scanning manuals and now busy sorting out software, unfortunatly work gets in the way. Just got to make sure it will fit in the 250MB webspace th...
by ChrisO
Tue Nov 27, 2018 7:42 pm
Forum: acorn atom and acorn system series
Topic: System 2 COS VDU Configuration
Replies: 4
Views: 802

System 2 COS VDU Configuration

I'm in the process of transferring paper copies of my dissassembled System 2 COS ROM onto a PC (CA65 Assembler) and in the process reviewing the comments I added back in the early 80's. I'm puzzled by the code that initilises the VDU controller, this is in the clear screen routine. Before sending th...
by ChrisO
Sat Nov 17, 2018 9:42 am
Forum: development tools
Topic: 6502 Assembler
Replies: 5
Views: 1775

6502 Assembler

I've recently come back to Acorn computers (see my Acorn System 2/3 refurb thread) and deciding which (PC) assembler to use ? Had a look at a couple: BeebAsm and CA65 which seem to be two extremes in terms of complexity ! BeebAsm is simple but entirely adequate for what I want though it doesn't seem...
by ChrisO
Wed Nov 14, 2018 7:47 pm
Forum: acorn atom and acorn system series
Topic: Acorn System 2/3 Refurb
Replies: 14
Views: 1886

Re: Acorn System 2/3 Refurb

DRAM's have arrived from RetroClinic and the board works, I now have more memory than I know what to do with :D

Chris
by ChrisO
Wed Nov 14, 2018 6:33 pm
Forum: acorn atom and acorn system series
Topic: Acorn System 2/3 Refurb
Replies: 14
Views: 1886

Re: Acorn System 2/3 Refurb

Hi Kazzie I wrote my own add-on for COS back in the early 80's under the name Oracle Microsystems, it added support for two UARTS, a dissassembler and a number of other useful commands. I used to sell them through Computing Today for those that remember that magazine (any of my old customers out the...
by ChrisO
Tue Nov 13, 2018 8:27 pm
Forum: acorn atom and acorn system series
Topic: Acorn System 2/3 Refurb
Replies: 14
Views: 1886

Re: Acorn System 2/3 Refurb

I've been making good progress over the last 3 weeks, more of the cards are now fitted and working including 2x8K RAM cards and the Cassette Interface (see seperate posting), all looking smarter with proper vero panels (thanks to a colleague, Colin H, for his help machining the panels and handles to...
by ChrisO
Tue Nov 13, 2018 7:33 pm
Forum: acorn atom and acorn system series
Topic: System Cassette Interface
Replies: 6
Views: 947

Re: System Cassette Interface

Hi Kazzie I've had another look at it tonight (spent last night fixing my Phillips LF Synthesizer that decided to blow its mains filter !), your analysis is correct - the design is marginal at best. I managed to get it working up to 900Khz with a Phillips 4024 rather than RCA. My fix is simply to re...
by ChrisO
Sun Nov 11, 2018 3:57 pm
Forum: acorn atom and acorn system series
Topic: System Cassette Interface
Replies: 6
Views: 947

System Cassette Interface

I've just wired up a System Cassette Interface on a Verocard to rack mount in my System 2/3 (I didn't want to convert my System 1 board). I'm not getting the right clock frequencies from the divided down 1MHz clock ? IC1, a CD4024B, is dividing by 27 and not 26 ? I've checked the original System 1 b...
by ChrisO
Fri Oct 26, 2018 8:31 pm
Forum: acorn atom and acorn system series
Topic: NOVEX 1414 Monitor RGB Connector
Replies: 6
Views: 901

Re: NOVEX 1414 Monitor RGB Connector

That looks like what I need, never seen one of these before though ? Technofix are on eBay so I can get one there.
thanks
Chris
by ChrisO
Fri Oct 26, 2018 7:41 pm
Forum: acorn atom and acorn system series
Topic: NOVEX 1414 Monitor RGB Connector
Replies: 6
Views: 901

Re: NOVEX 1414 Monitor RGB Connector

Hi Wim

Thanks for the info, by the looks of it your 8-pin DIN is slightly different to the standard ones. Normally the pins form a circle but the bottom pair of pins are slightly further apart on your plug. A normal 8-pin plug won't fit in the Novex socket.

Chris
by ChrisO
Fri Oct 26, 2018 4:26 pm
Forum: acorn atom and acorn system series
Topic: NOVEX 1414 Monitor RGB Connector
Replies: 6
Views: 901

Re: NOVEX 1414 Monitor RGB Connector

Hi Wim

Probably a 5-pin DIN, I havn't wired the panel up yet. My problem is with the connector at the monitor end.

Chris
by ChrisO
Fri Oct 26, 2018 9:39 am
Forum: acorn atom and acorn system series
Topic: NOVEX 1414 Monitor RGB Connector
Replies: 6
Views: 901

NOVEX 1414 Monitor RGB Connector

Hi All I'm trying to connect a NOVEX Monitor to my System computer using the RGB input rather than composite video but I'm struggling with the connector. Its an 8-pin DIN socket but doesn't seem to have the usual circular configuration of pins, the bottom pair are slightly further apart. I have seve...
by ChrisO
Wed Oct 24, 2018 9:56 am
Forum: acorn atom and acorn system series
Topic: Acorn System 2/3 Refurb
Replies: 14
Views: 1886

Re: Acorn System 2/3 Refurb

Which version of BASIC will you be using? The only known System 2 ROM images are at http://mdfs.net/System/ROMs/AcornMOS/System/COS/, so would like to see your COS and BASIC in case they're not dumped. [/quote] Will do, I have a couple of versions of BASIC in multiple 2716's, some appear to be corru...
by ChrisO
Mon Oct 22, 2018 8:43 pm
Forum: acorn atom and acorn system series
Topic: Acorn System 2/3 Refurb
Replies: 14
Views: 1886

Re: Acorn System 2/3 Refurb

Just in case its any use to you, I posted a [url=https://stardot.org.uk/forums/viewtopic.php?f=44&t=11313]scans of several System schematics[/url] to the forum a couple of years ago -- both the original and later CPU card schematics are there. It'd be useful to know if they contain the same erro...

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