New batch planned?

General discussions related to the Altair 8800 Clone

Re: New batch planned?

Postby RyanS » March 23rd, 2015, 1:53 am

Great news about the new run coming in April. Hopefully that means a growing community. It is amazing seeing what people have done!
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Re: New batch planned?

Postby Drunkle » April 1st, 2015, 9:47 pm

I too am looking forward to the next batch of units in April. I looking to get an optional Audio Cassette Interface form Mike.

I see that several Altair Clone owners have put their units on the internet for sharing and/or remote access. Here are pictures of my version on that theme. In my case I installed a Raspberry Pi (board on the right) in the case as my serial to network interface. I also wanted to be able to select between my external Wyse 55 terminal via the standard RS232 connector on the back of the Altair or the internally installed RPi network interface. I designed a second board (the one on the left) that accomplished this task. This board also allows me to take control of the main serial remotely via a interface line on the RPi if I forgot to switch it from the extra Aux switch on the from panel of the Altair. I'm building a third PC board to replace the prototype control line daughter board plugged in on top of the RPi.

Once I get some time, I'll document the whole thing and place it on my or some other website for others to look over.
Attachments
Altair plus RPi.jpg
A screen shot of my system from work.
Altair Clone plus Raspberry Pi plus Dual RS232 Contoler.jpg
The addition of a Raspberry Pi and a home brew RS232 AB switch.
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Re: New batch planned?

Postby AltairClone » April 2nd, 2015, 11:06 am

What a great looking job! Look forward to seeing the details posted.

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Re: New batch planned?

Postby JNZ » April 5th, 2015, 1:16 am

I'm super excited to get my Altair Clone on Wednesday!

In the meantime: is it possible to read/write to the 2SIO ports via BASIC, or does it have to be done in machine language? I already envision a real-world use for my machine: a watchdog that'll query my computer at work over serial, and if the response indicates that a critical script isn't running, it'll, well...do something. I wish it had GPIO pins. If I could simply assert a single line I could control a relay, which would be useful. Anything like that on the Altair Clone?
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Re: New batch planned?

Postby AltairClone » April 5th, 2015, 8:11 am

Yes, you can do some slow serial I/O in BASIC. See the "Serial I/O" topic in this forum.

Under software control, you can set the state of the RTS output from the 2SIO UART(s). These signals, in turn, connect to the CTS pin on the DB25s.

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Re: New batch planned?

Postby JNZ » April 5th, 2015, 3:07 pm

RTS and CTS sound quite promising! According to the 2SIO MITS manual, I can read the CTS bit (bit 3) from the ACIA status register. Based on this handy 2SIO echo routine (http://www.solivant.com/altair_bootload ... rs&pagen=1) I believe I can do:

IN 020
STA (lb) (hb)

and then examine the memory address A was dumped into to see the status register. Is this correct?

Thus my octal for front-panel entry would be:

000: 333 020 062 100 000 303 000 000

Which I believe is

IN 020
STA 20h
JMP 00h

When I run this (on my Altair Micro 8800 that I just got!) I get either a 2 or 3 in memory location 20h. Curious. I *think* this means that RDRF is full (I mashed some keys on my terminal) and TDRE is empty. (Receive buffer full and transmit buffer empty, respectively.)

Am I on the right track?
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Re: New batch planned?

Postby Drunkle » April 5th, 2015, 5:06 pm

So I have the primitive versions of the Serial AB switch and Raspberry Pi project details up on one of my web sites. This covers the details behind my earlier post in this thread. Have a look if you are interested.

http://www.astrorat.com/altair8800/serialabswitch.html For the Serial AB Project
http://www.astrorat.com/altair8800/altairmeetrpi.html For the RPi Project

Remember that this is a work in progress. Once I'm done, I'll re-post in a new thread.
If you have questions post them here or send me a private message.
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Re: New batch planned?

Postby JNZ » April 5th, 2015, 6:11 pm

That's a really cool project! I too have RPis lying around, and I like to make my own PCBs. I like the idea of using only PDIP. Did anyone do wire wrapping for these boards? That might be fun too.

This may be a stupid question, but how can I find a canonical port mapping for the 2SIO board (or emulation of the board)? Ditto for the other emulated hardware I'll have access to with my Clone.

If I want to read and write to the second SIO port, where should I look? The first seems to be 020 (status register) and 021 (data bus). Am I correct in thinking that I can do as I please with TWO IO ports? All this time I thought the Altair had one, so it really feels liberating to imagine what I can do now.
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Re: New batch planned?

Postby AltairClone » April 5th, 2015, 6:57 pm

The hardware emulated hardware in the Clone is listed in the Clone user's manual and duplicates typical Altair configurations. The Clone users manual and original Altair hardware and software manuals are available on the Clone support page.

The standard configuration for the 2SIO board puts the first port at octal I/O addres 020/021 and the second port at 022/023.

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Re: New batch planned?

Postby Drunkle » April 5th, 2015, 9:13 pm

JNZ wrote:That's a really cool project! I too have RPis lying around, and I like to make my own PCBs. I like the idea of using only PDIP. Did anyone do wire wrapping for these boards? That might be fun too.


Thanks JNZ for the kind words.

I did not go wire wrap during the engineering phase, I did create a breadboard version of the design for testing before I did the PC boards. Once I had everything working on the breadboard I made the PC boards. I did a small six board run with no silk screen or solder mask. I'm using two right now. As it turned out, there where only two bugs in the boards. 1) I turned around the power LED so the anode/cathode labels are backwards. 2) I turn around pins 1 (should be GND not +12VDC) and 2 (should be +12VDC not GND) on the power connectors J1 and J2. Had to make two cuts and one jump to fix that. I have already fixed the schematic and if I ever make another run of boards the CAD file for version 1.1 is also fixed.
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