14 Jun
2004
14 Jun
'04
11:49 a.m.
Hi all,
I've just been looking through a box of old computer-stuff and found the
following small item:
It looks like a cartridge (8x5cm) for an Amstrad with a passthrough edge
connector and a lead (70cm) comming out with a 5-pin DIN plug (male) at
the end.
On the label it says:
Cirkit
Prestel Link
Amstrad Interface
Any help appreciated. Searches on Google gives nothing!
Cheers,
Carsten
14 Jun
14 Jun
12:09 p.m.
On Monday 14 June 2004 21:49, Carsten Brasholt wrote:
On the label it says:
Cirkit
Prestel Link
Amstrad Interface
Prestel is/was an interactive service that usually used screens of textual
information, much like Teletext but you could do a lot more with it.
I think - i'm too young to have used it!
alex/melt
12:16 p.m.
Carsten Brasholt wrote:
Hi all,
I've just been looking through a box of old computer-stuff and found
the following small item:
It looks like a cartridge (8x5cm) for an Amstrad with a passthrough
edge connector and a lead (70cm) comming out with a 5-pin DIN plug
(male) at the end.
On the label it says:
Cirkit
Prestel Link
Prestel was a British dial-up service.
Amstrad Interface
Probably (part of) a modem.
Any help appreciated. Searches on Google gives
nothing!
Cheers,
Carsten
12:40 p.m.
New subject: What is this??? - Update
Hi again,
I just opened it up....
It's got 5 chips inside it.
74LS00
74LS74
8251AP-5
74LS32
4060
Does this help??
I know that prestel is some sort of teletext service - and perhaps a
dial-up service, but this unit doesn't really look like it's related to
a modem.....
Cheers,
Carsten
Carsten Brasholt wrote:
Hi all,
I've just been looking through a box of old computer-stuff and found
the following small item:
It looks like a cartridge (8x5cm) for an Amstrad with a passthrough
edge connector and a lead (70cm) comming out with a 5-pin DIN plug
(male) at the end.
On the label it says:
Cirkit
Prestel Link
Amstrad Interface
Any help appreciated. Searches on Google gives nothing!
Cheers,
Carsten
12:54 p.m.
New subject: What is this??? - Update
On Mon, 2004-06-14 at 21:40, Carsten Brasholt wrote:
Hi again,
I just opened it up....
It's got 5 chips inside it.
74LS00
74LS74
8251AP-5
74LS32
4060
Does this help??
I know that prestel is some sort of teletext service - and perhaps a
dial-up service, but this unit doesn't really look like it's related to
a modem.....
The 8251 is a serial comms chip - looks like you have an Amstrad
cartridge giving you a serial port on the DIN plug, to which you'd
connect up a serial modem in order to access Prestel.
I have a feeling Prestel was 1200 baud downstream and 75 baud upstream,
but someone else will know for sure :-)
cheers
Jules
1:17 p.m.
New subject: What is this??? - Update
Carsten Brasholt wrote:
Hi again,
I just opened it up....
It's got 5 chips inside it.
74LS00
74LS74
8251AP-5
74LS32
4060
Does this help??
I know that prestel is some sort of teletext service - and perhaps a
dial-up service, but this unit doesn't really look like it's related to
a modem.....
Cheers,
Carsten
Carsten Brasholt wrote:
I've not seen one of these but I have got a lot of amstrad stuff. Can
you send a picture. The 8251 chip is a uart so I would guess it is a
serial interface the 5 pin probably went to a modem.
Dan
Hi all,
I've just been looking through a box of old computer-stuff and found
the following small item:
It looks like a cartridge (8x5cm) for an Amstrad with a passthrough
edge connector and a lead (70cm) comming out with a 5-pin DIN plug
(male) at the end.
On the label it says:
Cirkit
Prestel Link
Amstrad Interface
Any help appreciated. Searches on Google gives nothing!
Cheers,
Carsten
3:20 p.m.
New subject: What is this??? - Update
Hi again,
I just opened it up....
It's got 5 chips inside it.
74LS00
74LS74
8251AP-5
74LS32
4060
Does this help??
YEs, a lot... Assuming there aren't significant numbers of transistors
around (to implement RS232 buffers in discrete components), then this
thing would appear to use TTL levels for the interface.
The 8251 is a serial chip (actually a USART, but I doubt it's eve used in
synchronous mode). It doesn't have an internal baud rate generator.
The 4060 is a long CMOS counter. My guess is that this produces the baud
rate clock, and in the absensce of any other chips, it's going to be
fixed at 1200/75 (there's no output port/mux chips there to allow for
selectable baud rates, and not really enough logic to implement that
using gates and FFs).
I know that prestel is some sort of teletext service - and perhaps a
dial-up service, but this unit doesn't really look like it's related to
a modem.....
It is a seiral interface, presumanly for a special modem.
-tony
15 Jun
15 Jun
7:28 a.m.
New subject: What is this??? - Update
At 01:20 15/06/2004, you wrote:
The Prism modems we used to sell for dialing-up Prestel when I worked at
Micronet (OK, give away with a subscription) back in '80s used a DIN
connection for their serial interface. It's highly likely this was
intended for use with one of those, as it was pretty much the cheapest
modem out there..
Prism, incidentally, manufactured the standalone modems, and an integrated
modem/interface/software box for the ZX Spectrum, and then promptly went
out of business. Micronet bought up all the stock, untested, and was
therefore able to give them away free if you subscribed. The number we got
back as faulty was amazing .... we didn't even check them when someone
returned one, just sent out another.. It was not uncommon for people to
get two or three faulty ones in a row....
Rob
I know that prestel is some sort of teletext service - and perhaps a
dial-up service, but this unit doesn't really look like it's related to
a modem.....
It is a seiral interface, presumanly for a special modem.
-tony 
2:48 p.m.
New subject: What is this??? - Update
-----Original Message-----
From: cctalk-bounces(a)classiccmp.org
[mailto:cctalk-bounces@classiccmp.org] On Behalf Of Rob O'Donnell
Sent: 15 June 2004 17:29
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: What is this??? - Update
Prism, incidentally, manufactured the standalone
modems, and
an integrated modem/interface/software box for the ZX
Spectrum, and then promptly went out of business. Micronet
bought up all the stock, untested, and was therefore able to
give them away free if you subscribed. The number we got
back as faulty was amazing .... we didn't even check them
when someone returned one, just sent out another.. It was
not uncommon for people to get two or three faulty ones in a row....
This is because the caps on the power input line failed; it was the most
common death of Prism VTX 5000 modems, and people who still want one can
have one new in the box because they're still available for about ukp15 with
the same faults they had back then :)
Cheers
w
14 Jun
14 Jun
3:16 p.m.
Hi all,
I've just been looking through a box of old computer-stuff and found the
following small item:
It looks like a cartridge (8x5cm) for an Amstrad with a passthrough edge
connector and a lead (70cm) comming out with a 5-pin DIN plug (male) at
the end.
On the label it says:
Cirkit
Cirkit were a component-supplying company in the UK who also sold some
kits (And ready-built items).
Prestel Link
Prestel was a British Telecom 'viewdata' service. IIRC it used 1200/75
baud modems (1200 baud from host to terminal, 75 baud from terminal to
host). Originally the only information transmitted from the terminal was
page numbers, so the slow link didn't matter.
Amstrad Interface
Any help appreciated. Searches on Google gives nothing!
My guess is that it's a very cut-down serial interface for an Amstrad.
Maybe RS232 levels, maybe not. Maybe fixed baud rates (1200 Rx, 75 Tx),
maybe not. Have you tried opening it up and seeing what chips are inside?
-tony
7376
days inactive
7377
days old
9 comments
8 participants
participants (8)
-
ard＠p850ug1.demon.co.uk -
carsten＠brasholt.dk -
classiccmp.org＠irrelevant.fsnet.co.uk -
dan_williams＠ntlworld.com -
julesrichardsonuk＠yahoo.co.uk -
kth＠srv.net -
lists＠microvax.org -
witchy＠binarydinosaurs.co.uk