Microsoft multiuser Basic for the Altair 8800

[Jay Jaeger]

First of all, safety first when working around these power supplies.
You have mains voltage exposed all over the place, including the front
panel switch.

What I typically do is take it all the boards out and disconnect the
power supply, and pull it out.  I then re-form the capacitors by taking
them off completely or, more often, unsoldering one lead.  In one case
recently the power supply was regulated (an Altos computer), and the
power transistors were inserted through the power supply case and into
the board from the backside, making removal both a pain and a little
risky, so I just clipped one lead of each larger in place to do the
re-forming (it turned out that in that particular case, they really
didn't need it).  I'd be pretty surprised if you actually had to replace
your capacitors.  For reforming I have had pretty good luck with a 4.7K
ohm resistor in serial with the capacitor, and in more than half the
cases, the capacitors really didn't need it.

The transformer is either good or not - and it is probably just fine.
Just measure its output voltages.  Do make sure that the transformer is
wired for your voltage depending upon where you live.  One could
disconnect it first, but the odds of it putting out too high a voltage
are very very slim, so long as it is wired for the mains voltage
wherever you happen to live.  Bad ones either put out nothing for one of
the voltages (open winding) or get hot (shorted winding).  Neither is
dangerous to the rest of the power supply.

Then, check all the voltages to make sure they are not way too high, and
throw and oscilloscope on it to make sure that there isn't a whole lot
of ripple (typically caused by a bad rectifier).   Remember that on the
original Altair and most S100 machines each board had its own regulator,
so this isn't an exact thing.  (On my machine, I actually had to add a
second 8V supply in order to provide power for a backplane completely
full of boards.)

For bootstraps, perhaps look for a ROM board on eBay (a Bytesaver or the
like), and burn yourself a ROM.

For a serial card, you can find T-UART or IMSAI MIO and the like show up
on eBay pretty frequently.  Be patient so you don't overpay. ;)   Real
MITS Altair cards come up far less frequently.  Make sure you research
(say, on bitsavers.org/pdf) which ones support current loop if you
really want to hook up a real teletype.

Not sure where you'd find your multi-user basic, but there is quite a
lot of Altair/S100 software available as part of the SimH environment,
and a separate web site at http://schorn.ch/altair_6.php

JRJ

On 7/15/2015 1:56 PM, Kip Koon wrote:
> Hi Drlegendre,
> How did you go about checking things out before you applied power for the first time (again)?  :)  I think I need to check out the electrolytic capacitors and the transformer at least.  
> In my system, the front panel is wired to the backplane along with the power supply wires so when I do power up, how do I protect everything?  
> There are screws the power wires come from, but they are difficult to get to.  Do I need to consider replacing any other caps?  
> Do you have a write up about your experience?  Any help you can give in the hardware department is most appreciated.  Thanks in advance.  Take care my friend.  
> 
> Kip Koon
> computerdoc at sc.rr.com
> http://www.cocopedia.com/wiki/index.php/Kip_Koon
> 
> 
> 
>> -----Original Message-----
>> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of drlegendre .
>> Sent: Wednesday, July 15, 2015 1:15 AM
>> To: General Discussion: On-Topic and Off-Topic Posts
>> Subject: Re: Microsoft multiuser Basic for the Altair 8800
>>
>> Hey Kip
>>
>> I can't help you with the software, but I just finished an Altair restoration (my first) a few months ago, and am still interested in getting
>> the machine connected and actually doing something interesting. The Altair was almost totally below the radar by the time I really
>> started getting up to speed on micros, which would have been around 1983-1984 or so. This one was sort-of given to me by a former
>> colleague of mine, around eight years ago. It was a total basket case, a real pile.. but it seems to be sorted at this point.
>>
>> It would be great if you'd let me follow along, keep in touch and let me know how you're working to get the Altair linked up to the
>> term, getting the system bootstrapped, loading software, etc.. that's been a problem here, figuring out the serial I card (or finding one
>> to replace it, that does have docs).
>>
>> Best,
>> Bill
>>
>> On Tue, Jul 14, 2015 at 11:56 PM, Kip Koon <computerdoc at sc.rr.com> wrote:
>>
>>> Hi Guys,
>>>
>>> I have finally decided to restore my original Altair 8800 which has
>>> been in storage for over 30 years.  Does anyone have a copy of
>>> Microsoft's Multiuser Disk Extended Basic for the Altair 8800?  When I
>>> was in college in '79 to '81, in the computer room was an ASR-33
>>> Teletype and 3 Learseigler terminals connected to an Altair 8800B.  An
>>> IMSAI was also there connected to one
>>> ASR-33 Teletype.  I'd like to resurrect this multiuser Basic software
>>> environment on my Altair someday once the restoration is complete.
>>> Any help in securing a copy of all the necessary software would be
>>> most appreciated.
>>> Thanks a bunch in advance.  Take care my friends.
>>>
>>>
>>>
>>> Kip Koon
>>>
>>>  <mailto:computerdoc at sc.rr.com> computerdoc at sc.rr.com
>>>
>>>  <http://www.cocopedia.com/wiki/index.php/Kip_Koon>
>>> http://www.cocopedia.com/wiki/index.php/Kip_Koon
>>>
>>>
>>>
>>>
>>>
>>>
> 
>