A Website dedicated to the Acorn System Computers

[ChrisO]

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 conjunction with trev-ham's replica boards this will give a boost to the number of System Computers out there.

Chris

[Kazzie]

Ooh, nice!

I'll have a good read of it this evening/tomorrow, and see if I can offer any suggestions (or additional content).

[flaxcottage]

Very interesting. I've never really seen one of these working let alone used one. They look rather Heath-Robinson and that is cool.

[richardtoohey]

Looks interesting so I'll have a browse around.

From the index page:

Please drop me an email if you spot any error's or omissions or you have any information that can be added to the site.

Umm ... I've got this thing about apostrophes, sorry.

[ChrisO]

'Fixed'

[gidandridge]

Hi and super interesting Chris!

I've never used an Acorn System computer before, but suddenly I now want to have one and play around. Looks really great.

Gav.

[BigEd]

Nice site! I would suggest that each page should have a link back to the home frame, in case someone lands on a subpage directly, like this
http://www.oddys.plus.com/Acorn/Systems/system_5.html

Which could happen from a search result, for example.

[tricky]

Nice website, how about adding an image map to the picture of your system so that you can hover over a section and get a pop-up description of each section?
I nearly bid on this film prop recently as it was local but I couldn't think of a use for it.

They are 4"-5" mono composite sony displays packed tightly together, but looking at some of the system racks, they might just have fitted.

[ChrisO]

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

[ChrisO]

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 currently at 216MB.

Chris

[Kazzie]

Ooh, nice!

I'll have a good read of it this evening/tomorrow, and see if I can offer any suggestions (or additional content).

Right, then. I've had a very enjoyable read of the site. The scans of the System 2 documentation, and of the 40x25 VDU card, were of particular interest to me, seeing at that's the next step for my System 1 after I finish its cassette interface. It's particularly nice to note the subroutines for using a VDU card with the System 1 monitor: I was expecting I'd have to get an ASCII keyboard built before I could do anything with the VDU!

I'd second BigEd's suggestion to have a link back to the home page from each individual page. I've already started sharing links to some pages of your site, and they might not find all the other goodness of your site without a link to signpost them back to the main page.

I'm glad to say I now know the difference between a System 3 and 3A: bare-bones vs all-included models. It might be useful to highlight which parts of the 2A/3A/4A were added on their respective pages.

The System 3 page says that an "ASCII keyboard and monitor where required" - I think that should read "were".

I saw that you noted the correction to the later versions of the 6502 card schematic. We found an error on the cassette interface schematic a few weeks ago. While it wasn't corrected in a later revision of the schematic (afaik), it might be worth highlighting on your site.

The pages on the COS and DOS mention supporting "a Centronics style parallel printer via a VIB" in the quoted text, but most readers probably won't know what a "VIB" is. Maybe adding a link to the Versatile Interface Board (and the other boards mentioned) at the bottom of the page would be useful.

I look forward to seeing and reading more about your own machines and your adventures with them as and when you have the time and the space available.

Well done!

[ChrisO]

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

Chris

[bprosman]

The site gone or down ?

[hoglet]

The site gone or down ?

Code: Select all

This site has been removed because it has exceeded its bandwidth allowance.

[Kazzie]

It seems that Plusnet not only limit you to a total of 250MB web storage, but also a daily traffic limit of 250MB!

ChrisO, I'm guessing that people downloading all the PDFs is what's eaten up your bandwidth. One way around this would be to upload those PDFs to archive.org, and just keep the web pages and images on your Plusnet hosting. The System 1 manuals have already been uploaded there, for example.

[ChrisO]

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

[richardtoohey]

Plus once you posted links here all the search engines would have started crawling your pages and using up some of that bandwidth to get and index the content.

Sure you'll be back online soon.

[roland]

It seems that Plusnet not only limit you to a total of 250MB web storage, but also a daily traffic limit of 250MB!

That is what I call retro hosting
Come on Plusnet, we're already living in 2019

[bprosman]

Otherwise I can volunteer to provide some hosting space.
I own the domain "retrocomputing.nl"

[ChrisO]

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

[Kazzie]

Nice to see the site back up, and with more added to it!

A point to note for any budding programmers is that the Acorn PROM board is designed to program National Semiconductor's DM74s571 PROMs. These are starting to get a bit rare these days. Another manufacturer, Tesla, made their own version, the MH74s571. This chip is output-compatible, but requires a different programming method, so the Acorn PROM board won't program those without some modification. Some wise heads have started looking at the problem (and interpreting the Czech datasheets!) on another forum, here: https://www.vintage-radio.net/forum/sho ... p?t=146388

I noted that in the 32k DRAM card's technical manual, it describes how to configure the clock signals for both the System and Atom, highlighting the fact that the Atom was designed with an interface for System cards. Did anyone here use this DRAM card to expand the Atom's memory past the usual 12K limit?

It also describes how to connect the card to the 6502A card "to be used in future equipment" (i.e. the System 5). As this issue (3) of the manual was published in January 1982, it indicates that Acorn had already (re)designed the DRAM board to accommodate the new, faster CPU card. This undated catalogue describes the System 5 as being shipped with the old 1MHz CPU boards at first, but the System 5 handbook, dated March 1983, is written as if the 2MHz 6502A board is the only one you'll find. I wonder what the exact timeline of its introduction was...

Also, the /VMA signal, mentioned in the DRAM manual and elsewhere, was required for the 6809 CPU card. So it's utterly irrelevant for us 6502ers.

[1987akaTheMoneyPit]

Please have a look, any errors or omissions let me know and I'll try and fix them.

The Schematic for the 8K RAM / 8K ROM Board, (100.003 Issue 3 13-Feb-1980) appears to be broken!

I'll work my way slowly through the pages so as not to effect the bandwidth . .. ...

regards

PS i forgot to add, the last time i used a System 1, was way back in '79 & '80! The "hex" threw out all MY System Cards as some point too . .. ...
PPS And all the Acornsoft software I had for the Atom . .. ...

[Kazzie]

Another correction:
The System 5 Memory Map Diagram has the 2K video RAM labelled as being from $1000 to $1FFF, but is shown as being in block 2 instead. The 32K DRAM is labelled as being from $2000 to $3FFF, occupying blocks 3-9. From the System 5 handbook, the default should be $2000 to $7FFF (blocks 2-7) and $C000 to $DFFF (blocks C,D) for loading BASIC from disk.

[ChrisO]

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.

[Kazzie]

You're welcome.

I hope to get back to System-related stuff in the coming weeks too, prompted in part by Beebmaster's sale of 8271 chips here. I've got a printout of the 40x25 technical manual courtesy of your site, and at least some of the chips I'll need to build it.

The vague plan is:

• Make a 40x25 VDU card, and mini-backplane with proper 5V power supply.
• Adaptation of 8K RAM 8K ROM card (use a single large SRAM chip rather than umpteen 2114s)
• Create an ASCII keyboard (possibly from a donor BBC keyboard)
• Build an FDC card

As you see, that 8271 I've bought is quit far down the list!

[bprosman]

What (Chips) do you have in mind for the VDU board ?

[dominicbeesley]

Just stumbled across this - an excellent site!

I've been pondering building a System X but my first stumbling point seems to be getting a card frame. You helpfully list the Verotec part numbers but I don't seem to be able to find an online catalogue anywhere - where did you buy yours...and how much do I need to save up.

I've bought a couple of second hand sub-racks from ebay but they aren't really suitable for something as good looking as yours!

D

[dominicbeesley]

Sorry, to clarify: an online catalogue with prices!

Any other ideas where to get a eurocard frame welcomed!

[dominicbeesley]

Sorry, to clarify: an online catalogue with prices!

Any other ideas where to get a eurocard frame welcomed!

[bprosman]

Any other ideas where to get a eurocard frame welcomed!

In Holland they regularly appear on "Marktplaats" , a Dutch sort of eBay or one of the "Radio flea markets" that are there.