31 Jan
2011
31 Jan
'11
8:33 a.m.
Tony Duell wrote:
That'd be great if you could at some point (or find someone with a scanner -
even a potentially-blurry scan is more interesting than nothing :-)
This thread's rather making me want to try to put together some form of guide
to RML bits and bobs and perhaps build up a better picture of what's what.
Yes, that's true - I've got one of the 480Z disk units and it very much looks
like a 380Z board, with PCB traces / pads for a 380Z bus connector (although
the connector and associated bus logic/buffers aren't fitted). It has ROM, RAM
(2KB SRAM), Z80 CPU, Z80 CTC, Z80 SIO and an 8877 FDC on board.
(oh, further point that I forgot to mention elsewhere - the network board in
my 380Z server was a mostly-blank 380Z board with a 480Z-style network
interface grafted onto it. I'm not sure if they were all like that, or if
there were earlier boards - prior to the 480Z's existence - which didn't share
any hardware)
Tony Duell
wrote:
Well, I've not got a digital camera yet :-). I wonder if I could convince
an HPCC member to photograph it for me at a meeting. Of course this means
finding the darn board... Incidnetlaly, I've just rememberd I ahve a
somwaht odd RML380Z board
soemwhere. It's got a bit off address deocding logic on it,
interconnected by PCB tracks. And 3 (I think) Z80-PIOs and a Z80-CTC in
wire-wrap sockets. The Z80 bus linesare are connected to the 380Z bus
connector, etc. the port lines and the counter/timer signals go nowhere.
There's also a little prototyping area on the board and space to fit some
header plugs. The idea is that you make your own custom interfce by
adding the logic you need and wire-wrapping it to the PIO and CTC pins.
Ans wire-wrap it to a header plug to connect a cable to the peripheral.
Hmm, is
there any way you can get a scan/photo to me? I'd love to see that. I've seen
another system with an analogue board inside, and enough guts for
six serial ports.
IIRC, at least one of the serial port boards was a disk cotnroller/serial
board with the former circuitry not fitted. There was also an
'intellegent' disk cotnroller/serial board which had a Z80 on it, I think
that was used, with different ROMs, as the controller in the 480Z disk
unit (which had a synchronous RS232 interface to the host). What I have never seen are any of the currnet loop
serial options which
were supposed to exist.
IIRC most, if not all, of the 380Zhs have rear panel cutouts for the GPIB
connecotr and the 'system controller enable/disable' switch. Whether the
board ever made it into production I don't know.
True, they do. I'd forgotten that GPIB is the same as IEEE-488 (all the 380Zs
I recall have the port labelled on the back as the latter).
I would
love to find some of the other board too. There was rumoured to
be an GPIB board. And an Econet interface. Oh, and a scheamtic of the
cassette control box would be intreresting.
GPIB I can imagine - I've never
heard of an Econet interface, though; that I haev never seen it, but 'The Econet Micro
Guide' by C. Dawkins says :
'Econet hardware has been impleemnted for the Apple ][, the Nascoms 1 and
2, the Research Machins 380Z and 480Z, S100 bus machines and all Acorn
computers, but only the last 4 are commecially available.'
A little later it says
'The 380Z/480Z/S100 interfaces have the same driver, receiver, collision
and idle detect circuiry as the BBC -- which at least ensures electrical
compatibility -- but the ADLC functions are performed by the SIO chip.
Only aobut half the hardware on the 380Z board is required for the
Econet ; the rest is a 64K RAM expansion and a ROM socket, with the
necessary decoding for the RAM to be paged as required. One important use
for this paged RAM is when the 380Z is acting as a fileserver -- the RAM
on the Econet board then provides cache memory which considerably speeds
up opeeration.'
The 'ADLC' is the 6854 of course, the 'SIO' is a Z80-SIO chip.
Wow, thanks for quoting that - interesting. I wonder if it was "commercially
available" for long... I think companies had to licence the use of Econet
technology from Acorn, and I've never seen mention on the Acorn side of RML
doing that. Doesn't mean that it didn't happen, but I'm surprised it's not
more known about, or that there isn't any apparent surviving hardware perhaps
schools were either with RML or with Acorn, but rarely both)
The advnatage of a normal light bulb is the positive
temprature
coefficient of the filament, and the fact that it will get hot enoguh
for that to make a different. I am not sure if that applies to heat
bulbs, though.
It should apply to tungsten-halogen bulbs, and AFAIK those hve not been
banned. I also believe the ban only applies to using bubls for domestic
lighting, so it's quite legal to use one as a current limiter -- if you
can get one.
It's frustrating - I've not seen many 'good' CFLs; they all have nasty
colour-cast, take ages to come on to full brightness, and never seem to
achieve nearly what the manufacturer claims in output or longevity. They won't
work outdoors here (too cold in winter), and are complicated (and hence
"costly") to manufacture and dispose of. Energy savings are even a bit dubious
for where I live - we run the heating for 6 months of the year, much of it via
resistive electric heat, so anything that incandescents lose as heat is still
doing useful work.
Someone, somewhere, decided that they tick a nice little 'green' box and will
save the world, though. Grumble! :-)
cheers
Jules