CB2 micro computer KIT

[sv3ora]

Hi!

I present you my latest project, my CB2 micro computer KIT.
It is a very cheap and very easy and quick to build microcomputer programmed in BASIC.

Website of the KIT: http://cb2.qrp.gr

Features:

• Standalone, no need for a PC to program and display.
• 16 foreground and background colors on TV SCART (PAL/NTSC), pseudographics and composite B/W. HDMI/VGA support with external adapters.
• Sound with envelope and volume adjustment.
• PS/2 keyboard (or USB with adapter), RS232, 2x serial TTL, LPT, 8x A/D inputs and I2C, all BASIC controlled.
• Tiny-BASIC with featured embedded editor, Chip8, SCHIP, 8080 and AVR-native binaries supported.
• 8 programs storage in internal flash, cross programs calls, external flash and EEPROM options.
• Terminal program, color terminal, X-modem transfer, PC connectivity.
• Games, applications and libraries available. Automatic program execute option on boot.
• Easy to assemble, through hole components and cheap!

And much much more to discover yourself...
Just hook up your TV and a keyboard and you are ready to go!

I hope you enjoy it, just as I do!
There are a few KIT pieces left.
Visit http://cb2.qrp.gr

Best regards
KOS

[sv3ora]

Two of my prototypes running my screen saver programs and networked through their RS-232.
A retro net cafe?

[granzeier]

Nice.

Many years ago, Byte had an article about using serial ports for networking ("Ultra-Low-Cost Network for Personal Computers" Byte, Oct 1981, https://archive.org/details/byte-magazine-1981-10, page 50.) This network used as little as two resistors and a diode and RS-232 connector for each port, but could be expanded to provide more speed and more nodes. This could easily give you the "net" part for your cafe.

Also, many years ago, a co-worker (in my USAF computer repair shop) had an idea of using many identical video game machines, which were networked together. These machines would be tied to a server, and could download any game for play. The player could walk up to any machine and request any game, rather than waiting in line for the most popular arcade game machine. No more wasted money, or space, on games which lost their popularity. This could also allow for multi-player games ("Multimachine Games" Byte, Dec 1980, https://archive.org/details/byte-magazine-1980-12, page 24,) something never seen back in the early 1980s.

I think that you are on to something. Can video arcades make a come back?   

[sv3ora]

Nice.

Many years ago, Byte had an article about using serial ports for networking ("Ultra-Low-Cost Network for Personal Computers" Byte, Oct 1981, https://archive.org/details/byte-magazine-1981-10, page 50.) This network used as little as two resistors and a diode and RS-232 connector for each port, but could be expanded to provide more speed and more nodes. This could easily give you the "net" part for your cafe.

Also, many years ago, a co-worker (in my USAF computer repair shop) had an idea of using many identical video game machines, which were networked together. These machines would be tied to a server, and could download any game for play. The player could walk up to any machine and request any game, rather than waiting in line for the most popular arcade game machine. No more wasted money, or space, on games which lost their popularity. This could also allow for multi-player games ("Multimachine Games" Byte, Dec 1980, https://archive.org/details/byte-magazine-1980-12, page 24,) something never seen back in the early 1980s.

I think that you are on to something. Can video arcades make a come back?   

Oh man, what a wonderful article! Thank you so much for digging this out. I can't hold myself back not to try it and if it works, I will add it to the board. I am not sure which of the versions though. A limitation is the voltage levels. The RS-232 port on the CB2 micro uses +-5v or something similar. I think the ULCNET can be made to work with these voltage levels. Well these won't be pure RS-232 but they will be compatible (after all the CB2 micro can communicate to PCs through RS-232).
What can I say, a great thanks!

In Greece, arcades were dissapeared within a few days following a regulation. It was so weird, one day you had arcades, the next don't!

[sv3ora]

Regarding the networked games, I have already done that. I have written the protocol for a server-client communication.
Both the server and the client are BASIC programs. The Server is your Game or it can be a BBS or any other service. The client is the Colterm program and it is designed to interact with the server in different ways. The user only has to write the server to do what he wants to do with the clients.
All comms are serial.
See here to find out how I did it http://cb2.qrp.gr/usermanual/#10_The_communication_program_Colterm

[sv3ora]

Many years ago, Byte had an article about using serial ports for networking ("Ultra-Low-Cost Network for Personal Computers" Byte, Oct 1981, https://archive.org/details/byte-magazine-1981-10, page 50.) This network used as little as two resistors and a diode and RS-232 connector for each port, but could be expanded to provide more speed and more nodes. This could easily give you the "net" part for your cafe.

Well, I have just realized this: In the CB2 micro, if you just short the TX and RX lines of the RS232 together, you get the same result as that the article states, without any additional diodes or hardware!

Transmitted data from each station loops back to this station but also sent to the other stations. I have tested it with just two stations and it works.

It essentially requires two wires, the GND and the common bus, since the TX and RX are shorted.

So effectively you receive the same results as that of the article without any diodes or even extra negative voltages in place!

[granzeier]

Very impressive - you really jumped on this one.

The thing about the RS-232 +/- 12V voltages is that it allows for much greater distances - but you probably would not need that for an arcade-type environment.

[sv3ora]

Well in fact, you can do more configurations the way CB2 micros have their Jumpers around the serial port placed. Based on different jumper settings on each computer:

You can loopback all computers (one transmits all the other listen)
You can make one computer transmit to all, but listen only from one computer.
You can make more than one computers transmit to all the rest but not between them, and listen from specific computers only.
And some other configurations.

What a great article it gave me good ideas!
Thankfully no hardware changes are required on the CB2 micros, it's all there already

[granzeier]

This is great. I'm looking forward to the write up. Also, I hope that my former co-worker runs across this, and gets some kind of enjoyment out of it.

[sv3ora]

This is great. I'm looking forward to the write up. Also, I hope that my former co-worker runs across this, and gets some kind of enjoyment out of it.

See here for a draft unfinished text on the networking
http://cb2.qrp.gr/extensions/#3_Local_Area_Network
I have to test the different scenarios to finish it.

[granzeier]

One question: with all of the TxD lines tied to only the TxD lines, how does a receiving computer read the data coming from the transmitting computer?
In ULCNet, the Tx and Rx lines are (essentially) tied together so that the data from the transmitting computer will reach all of the other computer's (including its own - so that the sending computer can detect collisions) Rx lines.

[granzeier]

One question: with all of the TxD lines tied to only the TxD lines, how does a receiving computer read the data coming from the transmitting computer?
In ULCNet, the Tx and Rx lines are (essentially) tied together so that the data from the transmitting computer will reach all of the other computer's (including its own - so that the sending computer can detect collisions) Rx lines.

Never mind; I see that you answered that in reply # 5 - I thought that I had seen that somewhere, but missed it when I looked again.

[sv3ora]

One question: with all of the TxD lines tied to only the TxD lines, how does a receiving computer read the data coming from the transmitting computer?
In ULCNet, the Tx and Rx lines are (essentially) tied together so that the data from the transmitting computer will reach all of the other computer's (including its own - so that the sending computer can detect collisions) Rx lines.

Never mind; I see that you answered that in reply # 5 - I thought that I had seen that somewhere, but missed it when I looked again.

Not #5 but #7.
The computers where the TX lines are tied toghether, and the RX lines tied together, cannot talk to each other. The ones that have their TX and RX lines tied in a null-modem configuration to the others, can talk to them. If the TX and RX lines are shorted, all the computers can talk to each other, including their own (loopback). By combining these settings (apart from the loopback case) you can do different network configurations.
For example you can have one computer to send to all the others, but to receive from them individually, meaning that the other computers can send to this computer but not send to each other.
And other configurations that I am going to explain in the website.

[sv3ora]

Hi,
I have made progress on the LAN networking for the CB2 micros. See here
http://cb2.qrp.gr/extensions/index.html#3_Local_Area_Network
Networking works as designed!

I am going to test the rest of the cases but it's really fun to see all the computers in the LAN to communicate to each other!

Have fun

[guenthert]

Well, I have just realized this: In the CB2 micro, if you just short the TX and RX lines of the RS232 together, you get the same result as that the article states, without any additional diodes or hardware!

Wut?  In RS232 the outbound signals are never tri state.  If you bind them all together there will be trouble.
 You don't want one peer's TX on high connected to another peer's TX on low.

There was a time, when RS422 (one master, multiple slaves) or RS485 (multiple peers) would have been used for such (and might still in industrial settings).

[sv3ora]

Might be like you say. All I know is that it works perfectly on actual tests I am doing here http://cb2.qrp.gr/extensions/#3_Local_Area_Network

[granzeier]

Congrats on the Hack-A-Day write up.
https://hackaday.com/2019/12/12/catch-the-old-school-basic-bug-with-this-computer-kit/

[sv3ora]

Hi, I have just completed all the networking scenarios for the CB2 micro. In this last example http://cb2.qrp.gr/extensions/#3.2.4_Connecting_three_CB2_micros_a_PC three CB2 micros are connected together with a PC and a dial-up modem in the same network and sharing data. Enjoy!

[sv3ora]

Check out the new games people are writing on the CB2 micro
http://cb2.qrp.gr/programs
Enjoy!

[sv3ora]

New Reversi game released for the CB2 micro!
http://cb2.qrp.gr/programs/index.html#2.3_Reversi
Enjoy!

[sv3ora]

I thought I should do an update on this.

microBBS V2 software (http://cb2.qrp.gr/programs/#4.4_microBBS2) has been written for the CB2 micro (http://cb2.qrp.gr)
With this one, you can run your own BBS on the MCU!

With love, for the retro fans.
Enjoy!

[sv3ora]

Hi guys

See how you can use your CB2 micro as an ASCII terminal with printer only output, or both screen and printer.
I wanted to create a TTY terminal with printer, just like the old teletype machines.
You can also convert your parallel printer to a serial one with this solution.

http://cb2.qrp.gr/extensions/#3.2.5_Connecting_CB2_micros_printers

And the software written for this, depended on the solution
http://cb2.qrp.gr/programs/#4.6_AsciiTERM
http://cb2.qrp.gr/programs/#4.5_printSRV

Enjoy!