Tony Duell wrote:
 An old Miracle WS2000, the black box with 3
knobs on the front that
weas commonly used with the BBC micro. It's an AM7910 and not much else,
I like it because it can be controlled from the front paenl rotary
swiches, and I Know exactly what it's going to do. Since I only use it on
a private system (my line simulator), I've eneabled the Bell modes by
remove the pin from the rotary switch. I'd love to find the autodial and
answer boards for it, but no chance...
There's also a kit (SK-1) to add a few parts which allow full software
I hadn't realised there was an official kit for that. I assume it alllows
full control via the 'user port' connector on the back, which is clearly
designed to conenct to a BBC micro user port. Incidentally, a couple of
the lines on that connector fo to the bases of NPN transistors (emitters
grounded) with a resistive pull-up, so you should drive them from an
open-collector or weakly pulled-up pin. The BCC user prot should be fine,
but take care if you're using something else.
control. Miracle Technology used to scrape off the IC
type numbers in a
vain attempt to prevent people working out what they were, and as you
Oh that stupid trick. It must delay my invesigations by at least 5 minutes...
can imagine I immediately decided to work out what
they were. Diagram
available if required :-) along with the original MT documentation.
Now, I don;'t have the official odcumentaiton, nor the kit. And my modem
didn't have the computer control ICs fitted when I got it.
Still, here are my 'instructions'. Please tell me what I got wrong.
Remove the frotn panel/modem PCB, take off the knobs and the nuts under
them. Separate the frotn panel (so you can see the component side of the
PCB. Take out that silly pin fro mthe mode switch that disabled the Bell
modes (required, I beleive, for BT approval)
Cut or desolder links J8, J9, J10, J11, J12, J13
Fit ICs : IC3 '155, IC5 '42 (Actually, isn't that needed for one of the
split-baud-rate modes to work correctly, maybe a Bell one), and IC6 '192
One problem you sometimes find when the SK-1 kit
autodial/autoanswer boards are fitted is that the internal 5V line gets
very noisy, and the modem does odd things due to switching glitches.
Really only a problem if you install SK1. Thin tracks and small
Hmm... I've foen the above mod and never had any problems. Naybe it's
only a problem if you use the computer interface .The PSU circuit has a
resisotr in series with the input to VR2 (77805. the +5V regulator) and
another one ins series iwth te inptu to VR3 (79L05), I assume to reduce
disipation in said regualtotrs. And to allow the inputs to wobble all
over the place. I would guess adding a capacitor from the input pin of
those 2 regualtors to grounds would be a good idea.
smoothing capacitors around the regulator are the
problem, easy fixed
with a little extra wire and a couple of caps.
Actually I might have a spare autodial board. Originally there was
supposed to be a single autodial-autoanswer (AA1) board but that was
withdrawn because of trouble with BABT. Later came separate autodial
Interesting. My modem has 3 sets of SIL headers inside, labelled as for a
dialer PCB, an answewr PCB anmd a TTL converter PCB. The last carries
power lines and the RS232 por signals, so presumably that board was a set
of 1488s and 1489s to convert the RS232 signals to TTL.
(AD2) autoanswer (AA2) boards and I remember both
being quite simple.
They probably were simple (the rest of the modem is), and I am sure I
could come up with something if I needed to. But for interest the
originals would be nice.
AD2 needed the software control kit (the older board
didn't, it was
entirely controlled by the DTR line) but the AA2 didn't. I worked out
I ownder why... The dialer and answer PCBs connect to the port lines on
the user port conenctors, as do the SK1 ICs, but I can't see why you need
schematics for some of them, but the autoanswer board
I built and used
worked in a slightly different way, using "ringback".
Can't help much with the Tantel, I'm afraid.
I did some work with
SoftMachinery for Acorn's Prestel ROM, and although I used to have the
source for the Tantel driver (called "tantrum" because of its
"reliability") I can't find it now. I used WS2000s and wrote drivers
for those ("madam", because it could be a little m.. with some version
of the ROM code).
THe Tantel unit I have is a stnadalone viewdata terminal (of the type
used for hom banking, etc before the days of the web), it doesn't conenct
to a home micro.
The main ICs are a 6504 (CPU, a 6502 with feew signals brought out, for
example onl 13 address lines), 2732A (4K firmware EPROM), 6810 (128 bytes
of RAM), 5101 (256 nybbles of battery-backed CMOS RAM), SAA5020 (teletext
video timing chain), SAA5050 (teletext character generator), a pair of
2114s (video RAM), TEA1002 (PAL video encoder), SAA5070 (Modem, UART, etc)
and a bit of TTL. There's a daughterbord identfied as 'filter module'
which contians the Tx andRx filters, tape loading amplifier (this thing
can same/load viewdata scereens on tape), etc.
Not too suprisingly, the modem coupling circuitry is simialr to that in
the HH Tiger. The RGB socket pinout is also the same as that on the Tiger
(only o nthis list would you find somebody comparing soemthing to the HH
I am annoyed that I cna't figure out how to configuer the dialer. I've
worked out jsut abotu everything else. and I've shown it can work.
Setting up the number to dial should be so easy, but I can't spot it.
I've even dumped the firmware and looked for useful text in it, nothing.