Dialing A BBS With A Spectrum 48k

Prestel & ViewData Services

In the UK back before the internet arrived there was a system called Prestel that provided various online facilities via a ViewData interface. This was similar to the Minitel system used in France and was closely related to Teletext.

Here is my Minitel terminal all setup to test my dial in gateway and connect to Level 29 BBS.

And here it is logged into Level 29 BBS. Notice the screen size is very restrictive due to the 40 column width compared to most ASCII terminals that have 80.

Micronet 800

As part of the Prestel service large customers could rent pages (known as frames) or the Prestel mainframe could hand off to an external system to provide other services.

One of the most popular services was Micronet 800, it provided chat rooms, multiplayer online games and message boards about various topics.
It was called Micronet 800 due to that being the entry page number provided by Prestel (you entered 800 to get to the main page within Prestel). 

The main problem with connecting to Micronet / Prestel was that you needed a modem, most home users of the time didn't own a machine with a serial port so in an attempt to get more users Micronet provided a package for the Spectrum. As the Spectrum 48k did not come with a serial port and couldn't display the resolutions required to show the ViewData frames this was a problem. Micronet got round this by providing a modem with built in ROM and hardware to update the Spectrum so that it could use the service.

The modem sits nicely under the Spectrum and connected to the bus at the back.

Modem Functions

When you connect the unit to the Spectrum it patches the ROM to load the Micronet code.
This gives you get a nice splash screen when the machine is turned on.

When pressing a key you are returned to the main system menu.

There is a mode for automatically logging onto the service (this remembers your ID number and enters it at the relevant prompt).
You can save frames, store programs and check the mailbox. The system also allows you to drop back out to Basic so that you can use the Spectrum without having to disconnect the unit.

Selecting log on asks for you ID and then gives you this screen.

At this point you have to manually dial the number to connect the modem.
When you hear the tone you flick the switch on the front of the unit to go online.

Problems Connecting

As the unit is designed to connect to a ViewData system at V23 (1200, 75) it does not have the modern modem facilities such as auto-bauding. It expects the other end to be the same. When trying to connect to Level 29 BBS we hit the problem as the modem on the other end is using Bell protocols and we are using the European CITT ones. The main difference being the tone frequencies that they use.

My modern modem has an AT command to switch modes but will usually just figure out the other ends requirements.

As we don't have that option I altered my ViewData system dial in gateway to connect to Level 29 via telnet. This allows me to dial my machine locally and the software then connects to the BBS via telnet does any character translation required and passes the data back to the Micronet modem.

Connected To Level 29 Via The Gateway

When I used this in my office it worked fine, I could type my user name (with a little bit of effort as the keyboard is a bit awkward on the Spectrum) but my monitor wouldn't keep the sync with the Spectrums video output and the image kept rolling. I then moved this downstairs on a very long telephone extension so that I could use the TV.
I think that something was getting messed up as the keyboard was not sending the correct key presses back to the gateway.

Anyway you can see the main login page that we are connected to. The Minitel terminal in the office works perfectly with this so I think I need to sort a shorter telephone extension cable out and try it again.

Retro Challenge - 2016/01 - Day 31

KryoFlux Imaging Machine

So putting one last push to actually get something done.

Got the machine i'm going to use for parts to make my KryoFlux imaging system.
The idea is that I have a single machine for taking images of floppy disks so that I can start on the task of imaging the large quantity of Acorn software that I have in my collection.

The machine will have both 3.5 and 5.25 inch floppy disk drives and will copy all images to my NAS storage or USB.
I will initially RDP to the machine to take images of floppy disks using the KryoFlux software but when I have the time I want to create a remote front end so that all I need to do is insert the disk and it will image and create the appropriately named files.
So that I am keeping the full copy of the disk I will store both the KryoFlux raw data and a image suitable for use with emulators. Any disks that are copy protected can then be re-written using the KryoFlux raw data.

Donor PC

The donor machine is an intel Core 2 duo PC, this used to be my main machine back a long time ago and has now just been in storage doing nothing.
Due to the case being a full tower one I want to move the motherboard to a new desktop case that will fit under my desk out of the way.

The machine had a pretty good graphics card at the time but this is now pretty obsolete compared even to a lot of embedded chipset graphics processors.

Extracted the motherboard.

Assembling The New Machine

To get the board into the new machine I had to remove the extra funnel for the processor fan and take out the filter that is fitted to the new case as the fan goes right out to the case lid.

Had a spare internal SSD with adapter kicking around from another project.

Fitted the KryoFlux into this space, will fit it properly but need some longer floppy drive cables and more power for the 5.25 inch drive.
The KryoFlux needs to be plugged into the USB, I may rob a USB front panel from a case to use internally.

All assembled in the case.

The 2 floppy drives for archiving.

Things To Do

Need to sort out the floppy cable and either make one the correct length or get one of the nice round ones I have in storage. Not sure if I have one with a 5.25 inch drive flat connector.

Currently installing the operating system so that I can actually image disks.

OS is now installed and I can remote desktop to the machine so that I don't need it connected to a monitor to use.

Fix the KryoFlux in properly (I have some PCB stands somewhere) and fit an internal USB to the machine so I can connect the KryoFlux without any external cabling.

This now has an internal USB header on the board which connects to the Kryoflux.

Image all of my disks (this may take a while).

Started this but its going to take a fair bit of time.

Goodbye Retro Challenge...

So this is the end again for another Retro Challenge, as has been common in the last few challenges my 11 month old has got in the way so I've not really got a lot done.
I am happy that I've manage to do some of what I set out to do. Mainly sorting my storage locker so that I can easily access machines and other stuff so that I can start to clean and fix them one at a time.

Enjoyed looking at everyone's blogs and hope to see you all next time.

BBS Throttle

Simulating 300bps Via Telnet

FozzTexx who runs the /r/retrobattlestations subreddit and Level 29 BBS was looking for a way to throttle telnet sessions to his BBS. He wanted to simulate the connection at 300bps.

As part of my ViewData BBS system I added in the facility to throttle the speed of the connection to give an accurate feel to way that it used to look.

Another item that is implemented is a way to pass through to an external BBS thus allowing me to either throttle or dial into telnet only ViewData BBSs.

My system was designed to handle ViewData only so I did a few adjustments and created a proxy service that will allow the connection to another BBS but will throttle the speed.


To connect to the Level 29 BBS with throttling enabled you can telnet (RAW) to the following ports...

Connect to - bbs.retroacorn.net

Port 6000 - 300bps
Port 7000 - 1200bps
Port 8000 - 2400bps

When I get the time I might add in a menu system to allow connection to other BBS systems.