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Help MITS Altair 680

O

osicollector

New Member
Joined
Feb 10, 2004
Messages
4
Hello there,

Can anybody hep I have just aquired an Altair 680. It appears to be almost complete and the case switchs etc are all in good condition. I have not been able to find however a schematic/Board layout. I obvious l want to check that everything is where it should be before I try to power up. Any help in obtaining these and any other information / software for this model would be appreciatted.

Regards Graeme
 
Hi thanks tried there no luck this is not an s100 machine but is a strange one all to itself.

Regards graeme
 
The Altair 680 is an SS50 machine rather then an S-100 machine.

You can buy a complete set of manuals (high quality reproductions) from Steve Shepard at www.altairmanuals.com. He is, from what I hear, planning on producing a CD that he'll sell as well.

Good luck with your new machine!

Erik
 
Wonderfull, Thanks a lot I have been to this site in the past but could not find it again. Hope to get a copy of the manual and get the beauty up and running along side my other machines.

Graeme
 
Osicollector and Erik,

I think it was SWTPC (SouthWest Technical Products Corp) who used the "SS-50" buss, which was, of course, a 50-pin buss. The Altair 680 actually used the same 100-pin connectors that the bigger Altair 8800s used, but the signal pinouts were different and it was not called an S-100 buss (or "Altair buss", which is what S-100 was originally called). I've seen several Altair 680 boards on ebay that were being incorrectly sold as "S-100" boards.

The physical differences between the two systems' boards were these: the Altair 680 boards were taller than the S-100 ones, and the 100-pin edge connectors were offset on the board differently than the edge connectors on the S-100s. Theoretically, this prevented a 680 board from being plugged into an S-100 socket and vice-versa, although if a kit builder failed to install card guides in his machine, either type of board would plug into either machine, and they could even be installed backward, Any of these incorrect configurations would result in the generation of much smoke.

alltare
===============================

Erik said:
The Altair 680 is an SS50 machine rather then an S-100 machine.

You can buy a complete set of manuals (high quality reproductions) from Steve Shepard at www.altairmanuals.com. He is, from what I hear, planning on producing a CD that he'll sell as well.

Good luck with your new machine!

Erik
Click to expand...
 
Re: Help MITS Altair 680

Did your 680 come with any daughter boards? Which ones?

alltare
=====================

osicollector said:
Hello there,

Can anybody hep I have just aquired an Altair 680. It appears to be almost complete and the case switchs etc are all in good condition. I have not been able to find however a schematic/Board layout. I obvious l want to check that everything is where it should be before I try to power up. Any help in obtaining these and any other information / software for this model would be appreciatted.

Regards Graeme
Click to expand...
 
Hi there,

The 680 is fairly complete as far as I can tell not having any docs at all. The front panel is complee and fully occupied.

The main motherboard is almost fuly occupied with a space at position L "what goes here?" EPROM u,t,v,w are all in place "help what do they do they are labeled A,B, UTIL2/2 and UTILK2/1" the rest of the board appears very clean and untouched.

I assume power goes in at j2 and serial port at j3?

J1 being the main bus which is extended upwards with a mits 680 expander board 3 position.

I have also a MITS 16k static ram board included and that it. This plugs into the expander .

Any help on this machine would be gratefully recieved the cost of the manual is a tad expensive once postage is included.

PS had time today to spend getting a SWTPC6800 up and running again . This is complete with an ac30 interface. Main machine now 100% ok with 2*4 ram boards installed. Complete with a mpc , mps and parallel interface. Just need to build some extra ram in to try and get he disk interface working. Thanks to M.Holley who has an excellent web site giving almost all the detail one would need in restoring one of these machines.

Regards Graeme
 
Hi,

I have a 680b and all of the basic system manuals (not the accessory cards) including the assembly instructions. Dang! I should have been making copies for sale. I don't suppose there is much demand, though.

The 680 is absolutely NOT an SS-50 machine!!! The 680 buss was unique (and pretty well designed according to people who worked in that area). Like the SS-50 system, it uses the Molex type connectors instead of card-edges & slots, which makes it look weird. The signals aren't too far from those used in SS-50 (close enough I designed & built an expansion board to use SS-50 boards in my 680b - they were easier to find). The pinouts for the signals is very different from SS-50, however.

I also did a few reversable mods to upgrade the ROM Monitor and double the clock speed (original was just 500 kHz). But its neat to have a machine so slow that you can literally tell when it is executing a loop by the flashing patterns of the data/address LEDs.

I'll check for you on the position L chip, etc.

--Wayne
 
hwhall said:
I have a 680b and all of the basic system manuals (not the accessory cards) including the assembly instructions. Dang! I should have been making copies for sale. I don't suppose there is much demand, though.
Click to expand...

There is a fairly good demand for the old manuals out there.

Steve over at Altairmanuals.com is rumored to be working on a CD of his docs scanned and OCRed.

Dynacomp Software is now selling 4 such sets of S-100 docs on CD with several selling a week at $10 or more a pop.

Bryan Blackburn put all of his Scelbi/Mark-8/8008 docs onto a CD and is also selling on eBay. . .

Then there is, of course, Herb Johnson who has been "Dr. S-100" for a long time and who has a huge set of docs that he will copy and sell for a very reasonable fee.

Mea Culpa again on the SS-50 gaffe! :)

Erik
 
All of the following is based on my 680b manuals. There appear to be some deltas between my 680b and your 680.

> The main motherboard is almost fuly occupied with a
> space at position L "what goes here?"

L is an 74LS74 needed only for the Baudot serial output option.

>EPROM u,t,v,w are all in place "help what do they do"
> they are labeled A,B, UTIL2/2 and UTILK2/1"

T & U were PROM Monitor program chips, 1702-A types. T was used for ACIA (TTY or RS-232) outputs, and T & U used together for the Baudot output option. Chips were supposed to be marked 680A for the ACIA monitor and 680B1 & 680B2 for Baudot.

The A & B marking you have is different than my documentation, but 2 chips makes me wonder if they might not have been for a Baudot output. The area within the silkscreened box marked "I/O"is wired differently depending on the choice of RS-232, TTY 20mA loop, or Baudot option. The Baudot option has the least parts count: only 1 xstr, 4 resistors, 1 diode and a jumper inside the box (only Baudot uses a jumper). Perhaps looking there will provide a clue about whether someone attempted the Baudot option. Don't have any info on the V & W chips. They may have been an accessory option. Those positions were empty in my machine.

> I assume power goes in at j2 and serial port at j3?

Yes, though J3 may be configured for one of 3 different serial outputs, as noted.
 
680(b) still runs fine

680(b) still runs fine

I have still have my Altair 680(b). It was upgraded with an adapter card to accept s100 cards. I added the Mikbug software in the extra 1702 eproms for motorola compatability. It has 12k dynamic (s100) ram in it. I used to load software with a "Bit Boffer" interface from a tape player. The SWTP 8k and 4k Basic was modded to run in the 680b. I also modded the swtp co-resident editor and assembler for the 680b. I do have the assembly and user manuals. I just fired it up and it still works ok. I have a copy of the altair basic on tape somewhere here. Sure brings back some memories.
 
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