Contemplating Altair Buss ZOOM Meetings ...

[Walt Perko]

Hi, 

I'm wondering if a once a month on a Saturday or Sunday would be good for starters?  

ZOOM meetings limited to 1hr.  ... or maximum of FREE ZOOM access.  

.

[Patrick Linstruth]

I’d be down with once a month on Sat or Sun.

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[Joseph Corda]

1hr sounds like a good starting point .. as for the day ..

If you do Sat I may not be able to make all of them,  as it's more likely I will be busy. Also my wife and I do "date night" on Sat
Thinking Sunday evening might be better for me as it is usually open and I'm home.

Either way ..let me know what is decided and I try my best to be there !  

[Terry Fox]

How would this be different from John's S100computers.com every other week Zoom?  Won't this additional Zoom dilute the S100 "fan base"?

Terry

[john]

So... the purpose being to discuss the Altair buss?

As opposed to the IEEE version?

I think all that has been well documented down through the ages.

-J

[john]

So...the topic is the Altair Buss ?

-J

On Saturday, August 23, 2025 at 12:49:27 PM UTC-5 jjco...@gmail.com wrote:

[Patrick Linstruth]

I have been following John’s S100 Zoom meets for a while. It is not a place for someone new to S100 or electronics. John's meeting is dominated by new, vintage software incompatible boards, integrating new technologies  such as FPGA with the IEEE bus. John’s group is geared towards advanced users that are long past restoring old systems using old hardware.

The Altair group is intended to be geared towards those of us that are still learning the basics of how the Altair/S100 bus works and are interested in vintage S100 technology, boards, and systems.  

Patrick

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/0b846d21-34eb-4abc-8fc1-d2d1ec018bbfn%40googlegroups.com.

[Walt Perko]

Hi, 

I've been thinking about this a lot lately ... I think there is room for a ZOOM ... not to exactly trim down the S100Group meetings just to the Altair 8800 ... but perhaps we should start out with discussions about getting started in the hobby, talk about the few common backplanes pros and cons, about the power supplies, how best to wire them up, what size wire, how to make nice neat routing etc.  Basically work up to board selections and initial tests as each board is installed.  

.

[Patrick Linstruth]

I agree. I think we need a meeting for beginners and people using the vintage hardware and software, not designing new boards.

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/1d1fc4da-22ba-4296-bb00-b605b6f0c1e7n%40googlegroups.com.

[Joseph Corda]

Guys
I would be interested in an Altair / S-100 general beginner type meeting.  Let me know the date/time for the first meeting.
BTW I would still plan on also attending John M. S-100 meetings as I am also very interested in hearing/learning about the projects that are being worked on.

Joe 

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/EBE6791B-2FCA-4BB2-B0B8-C298B04D3090%40deltecent.com.

[john]

I'd be interested as well.

I'm planning my current project that is an EPROM card that switches between different EPROMs via the front panel AUX switches.

Never heard of anything like that done before.  But it seems a good way to share address space.

Each EPROM would be accessed only briefly to load it's contents into RAM.

Like BASIC, or SpaceWar, etc.

-J

[Patrick Linstruth]

I am curious how you are going to integrate the AUX switches with the S100 bus so the EPROM card knows to read the sense switches.

Will the contents of the EPROM get moved to RAM through DMA or through software running on the CPU?

Sounds like a great topic!

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/30e079a1-3f70-48b3-8ec9-73607880bc9cn%40googlegroups.com.

[john]

In my A8800 I have a Cromemco 8K EPROM card.  I have a custom monitor program, some Dazzler games, and 4K MS BASIC.

BASIC is prefixed with what I call LZE code.  Meaning "Load to Zero and Execute".

To run 4K BASIC, I address the location in the front panel, hit EXAMINE, then set the sense switches for BASIC I/O, then hit RUN.

It loads from EPROM to RAM and begins executing in about 1 second.

I'd like to use the same technique on other software (like 8K BASIC).

Problem is the EPROMs eat addressable memory.

So... build a card with several EPROMs all addressed to the same place and add a switch to the chip enable circuit.

So now, before hitting RUN, I'll have to hold AUX momentary switches either UP or DOWN while it loads.

I could use an unused S-100 line or just use a wire and connector between the board and the switch directly.

I had a similar problem on an IMSAI 8080 back in the early 2000's.  I used a 512K flash RAM chip and used I/O ports to access it's contents in blocks.

It works well, bit I think the switchable EPROM card is a simpler solution.

I had to write a whole backend to support the flash RAM chip, even supported a simple directory scheme, load/save/erase/etc.

The EPROM  card would need none of that.

[Walt Perko]

Hi, 

I think you should look into a FDC+ board and then you can BOOT to any system you want simply by loading the .DSKs as needed.  That would be much easier and is already a well proven great solution for what you want out of your computer.  

The best thing is using Serial CP/M I have three 8MB floppies and one 360K floppy available to my computer and no FDC+ board, but with the FDC+ board you can still have two 8MB floppies and two 360K floppies ... with faster access (403K BAUD.)    

For me, the Serial CP/M just makes it all seem like it was back in the day ... I have mine set at 9600 BAUD and it's plenty fast.  

.

[john]

I already have an FDC+ in my A8800b.

The machine I'm using here is a plain A8800.  

I have my Altairs setup for 3 different states of tech development:

The B model has MITS 8" floppies.

The A model has ROM-BASIC and an ACR for cassette.

The original 8800 has EPROM and an ASR-33 TTY for I/O and paper tape storage.

So, I'm trying to keep to EPROMs on this machine.

(Excellent suggestion though!)

I do have lots of CP/M boxes around too.

Most notable is the restored Osborne I used in college.

It has a Gotek and USB drive.  Wonderful to use!

And surprisingly, almost all of my floppies from the 80's are still readable.

-J

[Terry Fox]

OK I will try to make it as well.  I already have a two-hour ham radio Zoom meeting on Saturday, so I may need to select which one if it's on Saturday.

Terry

[Walt Perko]

Hi, 

Okay, for me to send out an invitation to the ZOOM, I need people to send me their email address if I've not emailed you directly in the past.  

So far I only have Patrick's, Terry's, and Joseph's ... 

IF you know other people that might be interested or you think should give it a try ask them to email me direct too.  wperko [at] brainless [dot] org ... 

.

[Joseph Corda]

Walt and Patrick
I enjoyed the  Zoom meeting..and felt I got a lot out of it...only wish we had a little more time... 
Let me know when the next meeting will be.
Joe. 

[Patrick Linstruth]

I found it very useful too and think they will be very beneficial.

I will purchase a Zoom account so we can have longer meetings moving forward.

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/80905a3c-882e-4002-bf63-ec95bb267121n%40googlegroups.com.

[Walt Perko]

Hi,

Think about questions you have about your build, general questions about the S-100 hardware/software and you can post them here.  

Then we can arrange the questions in the order of importance to the group so we have a beginning answer to some of the questions at the start of the meetings, then later after we discuss one or two of the questions, we can save the rest of the meeting for general discussion or more immediate problem solving … or more question answers.  

Remember!  NO Question is a Stupid Question!  We all want to learn and maybe hadn't thought of that question yet.  

.

[Walt Perko]

Hi, 

Why can't a MASTER Z80 board be used as the CPU board in computer like the TeleTec Z80 SBC-1 I have or the S100 Master Z80 board?  

Why 74HCTxxx chips can't replace regular 74xxx TTL chips?

Can the S100 Bus Display board be used with another board at the opposite end of the backplane to do backplane tests for continuity and shorts etc.?  

Should we start a list of URLs for finding obsolete or hard to find components?  


.

[Joseph Corda]

Guys 
For the next Zoom meeting on 9/14 1pm PT here is a topic I would like to hear about.. but only if there is enough interest from rest of the Zoom group. 

1) Can someone give an overview/demonstration of using the 88-2SIOR1 card to load serial C/PM.  I would also like to learn more about using both Patrick's standalone serial server and a Linux serial server.  

Also I have some additional related questions that if time allows we could discuss

• Beside CP/M,  what other types of programs can be loaded with this method (like MITS Basic)?
• What format do the serial file need to be in (hex, binary, tap..etc)?
• Can we create our own serial files ?

Thanks
Joe

[Patrick Linstruth]

Joseph, I will put together a demo of the various 2SIO boards and Serial CP/M. It will force me to clean up my desk!

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/a5f80a93-5507-4813-b0b1-dcef19691ba1n%40googlegroups.com.

[Joseph Corda]

Thanks Patrick that would be great !

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