stardot.org.uk

I've made some progress with my setup. No joy with the 2nd BBC, the window comparator that drives CTS is producing erroneous pulses during a transmission. Thats whats causing the Net Error - can't find anything wrong with the board though so a bit of a mystery ? I'm using an original Acorn Clock (2-...

I'm having some similar issues with my 2 BBC set-up, one is reporting 'not listening' the other 'net error' when I send a notify. Looking at the data lines the 'message' is very short (just a few bits) from the one reporting 'net error' so I guess its aborting the transmission for some reason ? Both...

Found it ! A clue was the slow printing of the startup message, the CPU was overloaded with interrupts from the 6854. IC87 was generating loads of DCD pulses when it shouldn't, it looked like C17 was faulty so I replaced it but no change. Eventually found that pin 14 of the IC socket was folded unde...

I'm trying to get an Econet working between two BBC's (and later my System computers). One of the BBC's is fine, boots up and displays the Station ID. The other displays 'BBC COMPUTER 32K' slowly and then stalls ? If I then unplug the Econet cable it finishes booting ? Just wondering if this is as a...

Exactly it all works fine on the windows PC but breaks when transferred to TSOhost who presumably use a Linux platform.

Thanks for spotting those Dave. I use Microsoft Expression which has a Hyperlinks report which should catch broken links but it doesn't seem to be able to tell the difference betwwen upper and lower case ! In places I accidently used MK14 instead of Mk14 and it doesn't spot it ! (also Prom and PROM)...

Hi Ian The Mk14 is interesting historically because it led to the creation of Acorn, building a replica was a just a bit of fun. I' don't think I'll be doing any actual programming on it, I'm not familiar with the code and anyway I'm too used to a proper keyboard and display ! I'm very unlikely to b...

Its not an Acorn board and has no markings so I don't know where it originated from. I havn't got around to trying it out yet, its on my (long) list of things to do. It just happened to be with other Atom stuff when I took the photo !

Of course, silly me missed off the link !

As promised my Acorn System Computers Website has undergone a refresh over the last couple of months and has now been updated, enjoy !

Please let me know if you spot any errors or omissions.

Chris

I'd quite like to have a go at building a Softy Programmer, would have liked one in the day but far too expensive. I have a copy of the manual which has circuit details but no code ? Don't suppose anybody here has one and could dump the 2708 EPROM ?

Chris

Looks like its back up so just a hiccup from the hosting co ? I'm happy for copies of the info to be taken off the site, don't want it to get lost though I've no intention of closing it any time soon. I would be interested to know how well the RPi works as I'm thinking of ditching the host co next y...

Hi All Just spotted this post and can confirm that its not working, don't know why ? Its hosted by TSOHost ? I'll leave it till tomorrow and see if it comes back before trying to contact them. In the mean time you should be able to access a copy on my Raspberry Pi here http://81.174.146.201:8080/aco...

The 80 column VDU card works in a similar fashion though the designer has taken short cuts and not used D-type flip flops but crude RC delays. Its not very effective, neither accurate or consistant. I've modified the design to incorporate D-type delays which gives a far more stable display, just wai...

Good work Kazzie, I've built a couple of these boards and didn't spot that mistake ! I've added a note to the website.

Chris

I still have my Taxan/Kaga KP-810 that I bought from Watford Electronics back in the early 80's. I remember travelling there by train and carrying it home ! It hasn't been used for at least 25 years but I still have half a box of fanfold paper and a few ribbons (probably dried out ?). I plan to dig ...

Kassie

I've had a look at my original Issue 3 PCB and that is wired as per the Issue 4 schematic i.e. with the buffer after the oscillator rather than before.

Have you wired IC2 pin 2 correctly ?, it's shown tied to +5V on both versions of the schematic but it should be tied to 0V ?

Chris

thanks Kazzie, well spotted - fixed.

I've had a busy summer on non-Acorn stuff but should have some time soon to get back on this and update the website with progress.

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...

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...

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 ...

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...

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 (...

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...

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 ?

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...

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

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

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

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

Chris

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...