Teaching Old Micros New Tricks
October 2009 meeting – report by Steve Fryatt (pictures by Joel Rowbottom)
The October meeting opened with a reminder from Rick that we are still looking for a Meeting Coordinator to replace Chris Hughes. Chris has carried this task out for many years, and has finally decided that he needs to take a break from it. The diary is currently filled until February, and after that there are a number of provisional speakers pencilled in – we now need someone from the club to step forward and arrange suitable dates for them. This isn’t a particularly onerous task, but it is vital if we are to continue to have an interesting schedule.
New tricks for an old Micro
With the announcements out of the way, Rick introduced Joel Rowbottom, who was going to talk to us about some of the things that can be done with a BBC Micro in 2009. As anyone who attended the Acorn World event in Huddersfield – or read the report in last month’s newsletter – will know, there’s still a lot of interest in the old Beeb. Not only that, but there are even new hardware upgrades being produced.
Joel had with him a Master containing a number of added extras. In fact he even had it connected to the projector alongside a iBook: the sight of the old Mode 7 start-up prompt on the big screen might have given a few people cause to do a double-take on arrival at the meeting.
The talk opened with Joel admitting that he was “a BBC Micro addict” – showing us photos of his garage stacked with old 8-bit hardware in order to prove the point. He wasn’t alone, he said: there has been a massive rise of interest in the old systems in recent years. This is basically down to nostalgia: the desire to remember and use software such as Elite and Chuckie Egg, as well as to save such titles for the future.
The nostalgia isn’t all straight-forward, however. The original Beeb is fast approaching 30 years old, and is now well beyond its original design life. Discs, particularly the 5¼" floppies used by early Acorn systems, oxidise and die – and new ones are becoming very hard to come by. The old machines also had a few issues with the millennium bug: in the Master and some fileservers.
As a result, a number of enthusiasts have started to look at solutions which can bring the Beeb up-to-date. As far back as the late 90s, Rob Sprowson (whose name cropped up a few times during the evening) produced the ‘Domesday ROM’ to fix the Y2k problems in the Master and add support for timezones. Simple and cheap, this was the sign of things to come.
Since then, various developers have released fixes for other bugs in the Beeb’s MOS. These particularly relate to disc access, not least because Acorn’s developers (not unreasonably) didn’t consider that their system might have to access hardware that hadn’t been invented at the time. Mark Haysman at Retroclinic has produced a small switchable OS ROM board to allow different versions to be selected (literally) at the flick of a switch, and this is easy to use with the patched versions.
As already mentioned, floppy discs are fast becoming history: Joel said that many of the ones he is given now are already unreadable. Original BBC hard discs are scarce and Econet is slow and unwieldy. It seems obvious, then, that someone would have the idea of adding IDE and USB interfaces to the old systems.
The ‘correct’ way to do this, of course, is via the 1MHz Bus, and Jonathan Harston (or JGH) produced a simple 8-bit IDE interface. This works fine, but being 8-bit it limits the user to half the available storage on the device. Having said that, on a modern disc that’s still a lot more space than a Beeb is used to.
Another option came from John Kortink, who produced the GoMMC interface to allow MMC cards to be fitted inside the machine. Aside from the problem of needing to take off the machine’s lid, Joel said that the interface could be picky as to what cards it talked to, it was sometimes unreliable, and MMC cards (and the GoMMC interface itself) were now becoming as hard to find as floppies themselves.
Enter Mark Haysman again, who produced an external compact flash interface for the 1MHz Bus. Still only 8-bit (so with the same problems as JGH’s IDE interface), it was cheap, reliable, easy to use and well-supported. Oh, and at Acorn World, someone had the idea of trying it as a very large Econet Level 3 fileserver – it worked fine, apparently.
The full monty
Not content with CF cards, Mark continued development of the reader and came up with the Retroclinic Datacentre. Also suitable for connecting to the 1MHz Bus, this has support for IDE and USB in the same box, as well as providing a very big RAM disc. The USB-A port can take FAT32 USB drives, while the USB-B port can be used as a slave serial port.
Storing files from the Beeb on modern discs can be a problem: not least because the concept of load and execution addresses never really caught on beyond ADFS on RISC OS. To get around this, enthusiasts have come up with disc image file formats: .SSD and .DSD are for single- and DFS discs, while .ADF is for the ADFS format. ‘ELITE.DSD’ can even be downloaded from Ian Bell’s website!
The datacentre comes with support for these formats built in: *IMPORT will mount an image file on a modern disc and then treat it as though it were a real floppy, while *EXPORT can be used to archive old floppies to modern media before they finally die. Most importantly, the process is very quick.
In order to work with new discs, however, it’s necessary to have a hacked ADFS which understands IDE commands. The interfaces usually include this, and the switchable MOS board also contains it. The downside is that it isn’t possible to use modern storage media alongside an old ST506 drive.
Yes... that really is 32GB storage capacity on a Beeb – but trying &7D4250000 in BASIC will actually get the reply “Too big”
Isn’t 32K enough for anyone?
By modern standards, the Beeb’s 32K of RAM seems a little small. There’s a bit more on a Master, of course, but Joel said that even that wasn’t enough for some people. Of course, it’s always been possible to expand the Beeb by adding a co-processor over the Tube, using the Micro for the I/O and doing the hard work on the co-pro.
Acorn produced a number of systems in the familiar cheese-wedge boxes over the years: 6502, Z80, 68000 and even an ARM1 evaluation system. However, as you’ve probably guessed by now, these weren’t enough for some enthusiasts. Enter Rob Sprowson again, and the ARM7TDMI co-pro board.
Clocked at 64MHz, this comes with 16MB of RAM as standard and can run ARM code, relocatable modules and BASIC V from the Archimedes. It can even emulate other processors, which opens the possibility of doing disturbing things such as running 6502 code on an emulated Beeb inside the ARM7 system attached to a real Beeb. And if you have one going spare, the PCB even fits inside a cheese-wedge box from an old Teletext adaptor for complete authenticity.
An alternative option is John Kortink’s ReCo6502, which is a 65C02 co-pro running at a ‘classic’ 3MHz or a ‘contemporary’ 14MHz. Alternatively, it can be fitted with a 65C816 running at full speed. Designed as a drop-in replacement for the PCB in Acorn’s original 6502 co-pro, it’s necessary to have access to a Tube ULA to make it work.
Joining the network
Having dealt with storage, there was one more obvious thing for the enthusiasts to look at: replacing Econet. Conventional wisdom would suggest that there isn’t space in a Beeb’s memory for a TCP/IP stack, but still – Ethernet would be nice. Enter Rob Sprowson (again) with the Ethernet interface for the Master.
Designed as a plug-in card to fit where the Master’s Econet interface would have been, it has all the software it needs in ROM and can talk Samba with Windows shares (or anything else that emulates them). Best of all, the socket on the back is an ‘Econet style’ one, meaning that the board comes with a rather desirable ‘RJ45 to Econet’ lead.
Once fitted, accessing a server is just a case of using *MOUNT and then accessing the files that it contains in the usual way. Joel was able to show this in action, and read files directly from a netbook running Linux.
The retro community
Joel finished by summarizing what was available, and noting that most of the items he had shown would cost less than £70 when bought online – apparently this was useful when justifying new toys to his wife. He advised buying kit (particularly old Beebs and Masters) from established members of the community (avoid those on eBay shouting “R@RE! LOOK!”), and noted that Retroclinic often sold reconditioned systems with refurbished PSUs for around the £100 mark.
There’s a thriving community online, and Joel pointed us towards the Stairway To Hell web forum and the BBC Micro Mailing List. A number of sites are archiving old documents and software, and these can be good places to look for information.
To Find Out More
The developers behind the hardware are:
In addition, Chris Whytehead’s site – at acorn.chriswhy.co.uk – contains many archived manuals for hardware and software. Finally, other Beeb enthusiasts can often be found in the forums at www.stairwaytohell.com or on the BBC Micro Mailing list: mdfs.net/Archive/BBCMicro/help.
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