RE: [Altair Computer Club] Re: Tips needed Before Powering Up My Old Altair 8800
Thank you for those kind words. I knew there was a great reason why I loved all those Williams Video Arcade games. I had a lot of fun times with them. It is fascinating to know that you guys are still interested in the 6809 also. Actually, my Altair 8800 does have only three 4 slot motherboards hard-wired together, so there is room to install a separate bus. I had not thought of that. I’d also like to have a complete separate 6809 system. I just don’t know which version from those you stated that I want to build up. That would be a very fun project. Being in high school in the mid ‘70s, I was never able to build my own 6809 based system nor an Altair either. I was also fascinated by the IMSAI computer in the Wargames movie.
The Ackerman 6809 SBC board does sound interesting. I was looking at the write-up on S100Computers.com about it. I like to get one some time.
Like you advised, I do want to go very slow with this project. I want to get started on this project as soon as possible, so just let me know what I need to do. I went out last night to what we call our warehouse in our backyard and photographed all the boards and chassis of the Altair 8800. After looking at everything I made two observations. The front panel is hardwired to the motherboard and I don’t think I have any RS-232 ports to hook my HP laptop up to for use as a terminal for testing, so I know I’m going to want to do some upgrading eventually. So how would you go about testing the power supply with a big circuit card attached? Thank you in advance for all your help. It is much appreciated. It going to be a lot of fun talking to you guys! J Keep up the great work you all are doing!
You've come to the right place for working through your first-time startup process. The level of expertise assembled in this group is incredible. I am often shocked by the level of details these guys can recall about a project from 1975 that I couldn't match from one I did two years ago. I'm sure they will have you start at the most basic level and build up to full function slowly.
I have several engineers who also have fond memories of the 6809. With the ability to have 16 bit registers, position independent code, reentrant code, multiply, fast interrupts, interesting address modes, etc. it's a fun piece of hardware and a major upgrade to the 6800. Most of our favorite Williams video games were 6809 powered.
Ackerman 6809 SBC in an Altair
I cannot find a reference to any other S-100 IEEE-696 board other than the Ackerman. The S100Computers.com site has a very nice picture and short write up. Several of us could probably source a manual for you. I would consider the complexity of creating a separate bus and power segment inside your Altair for your favorite 6809 SBC as a moderately complex project. The Altair chassis is flexible and there is more room in there than most people could ever hope to fill and power with the standard factory design. So creating a dual system is doable, but the team will want to get you through the basics first to get you to a healthy stock Altair I would guess. The 6809 was far more popular on the SWTPC, GMIX, Smoke Signal Broadcasting family bus if you decide to get a dedicated box for that.
- | From: Stephen A. Arnett <sarnett@...>
| The 6809 was far more popular on
| the SWTPC, GMIX, Smoke Signal Broadcasting family bus if you decide to
| get a dedicated box for that.
Those SS50 systems were great 6809 boxes that you could get inside.
They would be my first choice if I wanted to play with 6809 hardware.
I imagine that the Radio Shack Color Computer ("CoCo") was the most
ubiquitous programmable 6809 box in North America. But you cannot
tinker as much with a CoCo as with the SS50 boxes.
The CoCo 3 was something I (a Unix guy) thought was interesting at the
time: it had an MMU and ran OS9, a quite good modest Unix-like system.
The Vectrex <https://en.wikipedia.org/wiki/Vectrex> had a 6809 inside
and folks hacked it too. They are probably widely available.
The 6809 definitely has a better instruction-set architecture than the
8080 or Z80. The trouble with aiming for better and better is that
that logic drives you to the present. Like: if the 6809 is good, why
not go for the better 68000? And the x86-64 instruction set is much
better than the 68K's.
- These guys,
also have a 6809 project which adds a coprocessor to a Z80 base platform
and allows you to mess around with a 6809 while the underlying Z80 runs
your CP/M to put and get stuff to disk, etc.
It's not legacy but maybe more available ...
On Thursday (03/14/2013 at 04:00PM -0400), D. Hugh Redelmeier wrote:
> | From: Stephen A. Arnett <sarnett@...>
> | The 6809 was far more popular on
> | the SWTPC, GMIX, Smoke Signal Broadcasting family bus if you decide to
> | get a dedicated box for that.
> Those SS50 systems were great 6809 boxes that you could get inside.
> They would be my first choice if I wanted to play with 6809 hardware.
> I imagine that the Radio Shack Color Computer ("CoCo") was the most
> ubiquitous programmable 6809 box in North America. But you cannot
> tinker as much with a CoCo as with the SS50 boxes.
> The CoCo 3 was something I (a Unix guy) thought was interesting at the
> time: it had an MMU and ran OS9, a quite good modest Unix-like system.
> The Vectrex <https://en.wikipedia.org/wiki/Vectrex> had a 6809 inside
> and folks hacked it too. They are probably widely available.
> The 6809 definitely has a better instruction-set architecture than the
> 8080 or Z80. The trouble with aiming for better and better is that
> that logic drives you to the present. Like: if the 6809 is good, why
> not go for the better 68000? And the x86-64 instruction set is much
> better than the 68K's.
> Yahoo! Groups Links
Your SIO-B TTL serial board was never (to my knowlege) sold as a separate board- It was piggybacked with the MITS modem board to form what is known as an 88-ACR cassette interface.
There were 2 other SIO boards- the SIO-A for RS232 communication, and the SIO-C for 20mA TTY use. I haven't investigated too much, but I don't think it would be a real big deal to convert a TTL SIO-B to a board that supports RS232. But before you mod it, bear in mind that the ACR board set is worth quite a bit.
There's also the 2SIO board, which uses a different UART and can be configured for any of the above 3 signal types (no modem function, though).
Too bad you don't have a serial number sticker, but at least you can usually tell if an Altair was factory assembled or kit-built by looking for residual flux around all of the solder joints on the front panel. MITS always removed it and kit builders seldom did. Date codes on the front panel chips can usually tell you approximately when it was made or kitted- probably shortly after the most recently dated chip.
To check the power supply voltages, you could disconnect the power wires from the front panel, or you could disconnect them at the P.S. You would have to check the schematics for the correct wires and as you noted, there's a little work involved. Be careful with that wire bundle going from the mother board to the front panel. Those wires are easily broken off at the solder joints if they're flexed too much. In fact, your existing front panel problem, if there really is one, could be because one or more wires are already broken off.
I would probably leave everything hooked up and just try to power up, get the readings, and power back down as quickly as possible, while keeping my fingers firmly crossed. That's obviously not the safest way to go, but at least all the plug-in boards will be safe.
--- In email@example.com, "Kip Koon" <computerdoc@...> wrote:
> The board compliment of my MITS Altair 8800 computer which by the way has
> absolutely NO serial number sticker anywhere inside or outside of the case
> is as follows (All quantities are 1 unless specifically mentioned):
> Gray Painted with White Lettering Silkscreened Metal Front Panel with all
> MITS 8800 D/C Front Panel Board
> 3 - 4 slot Motherboard Boards
> IMSAI RAM-4A Board
> MITS 88 SIOB Serial TTL Board Rev 1
> MITS 88-4 PIO Rev 0
> CRT Board Processor Technology 1976
> IMSAI PIC-8 Rev 3
> ALS-8 8K PROM 34 Processor Technology Board with 13 proms populating the
> IMSAI RAM 4 Rev 1 fully populated
> IMSAI RAM 4 Rev 1 missing 4 ram chips (Anybody have 4 ram chips to spare?)
> MITS 4K RAM Board Rev 0
> MITS 8800 CPU Rev 1 Board with a C8080A chip
> TDL The ZPU Board Rev 1
> IMSAI CR1 Rev 1 Board missing the 4 RCA jacks and last two 16-pin sockets
> MITS Modem Board not S-100
> IMSAI CR1 Rev 1 Board fully populated with all 4 RCA jacks but missing
> something from the last two 16-pin sockets, may be solder wire headers?
> Godbout 1977 Motherboard Terminator Board
> Seems to have full power supply. The front panel has a wire bundle soldered
> to the right-hand side of the motherboard - no connector. How do I test the
> power supply with the front panel connected? I can't seem to get to the
> screws of the terminal strip of the power supply. May be I need to remove
> some of the plastic card guides from the motherboard and disconnect all
> power wires connecting the motherboard to the screw terminals of the power
> supply? All S-100 cards seem to be free of dust. The dip switch blocks of
> various cards seem to have a little something all around them on their
> sides. No floppy drives, nor controllers much less hard drives of any
> kind. Best I can tell I have an 8080 or Z80 up to 16KB of RAM, 8K prom
> monitor, with Cassette Recorder for storage, with up to 4 6820s for parallel
> I/O, a serial TTL port, and a PIC-8 (whatever that is) computer. I'm not
> even sure if I got it running if I could even connect a terminal to it -
> Serial TTL? I would need an RS-232 board. Anyone with a spare? Well, that
> is about it. What can I do with all of this and what upgrades could I make
> - more RAM, virtual floppies and virtual hard drives may be? This will be
> an interesting journey!
> From: firstname.lastname@example.org
> [mailto:email@example.com] On Behalf Of steve
> Sent: Wednesday, March 13, 2013 10:10 PM
> To: firstname.lastname@example.org
> Subject: [Altair Computer Club] Re: Tips needed Before Powering Up My Old
> Altair 8800
> MITS never made a 6809 board for the Altair 8800. I don't know of any other
> manufacturers who did, either. However, the Altair 680 used a Motorola 6800
> You will find a lot of good info about troubleshooting in the message
> archives, if you have the patience to wade through them.
> For starters, remove all daughter boards from your Altair and power it up
> and check the 3 bus voltages, which are unregulated DC. They should be about
> +16, -16, and +8. And of course, never pull out a board while the computer
> is powered up.
> Just curious- what's the board compliment of your Altair? To be functional,
> you should at least have a CPU board, some RAM, and some kind of I/O.
> --- In email@example.com
> <mailto:altaircomputerclub%40yahoogroups.com> , "drwho7777"
> <computerdoc@> wrote:
> > Hello Everyone!
> > I have an old Altair 8800 that I recieved in the early 80's and I had
> practically forgotten about it until reently. When I received it, I was told
> that the front panel had a problem, what I don't know. I have never powered
> it up and would like to know how to make sure everything is ok before I
> apply the Smoke/no smoke test. Any help would be well appreciated as I know
> very little about Altair 8800s and even less about 8080/Z80s. I'm a Motorola
> man and very much like the 6809, so I was wondering... Has anyone ever
> created and 6809 CPU board for the Altair line of computers. I hope I am not
> crucified for asking this because I know the first processor people learn
> usually is their favorite and I certainly wish to not step on any toes here,
> but the thought was on my mind. Thanks again for any help in helping me to
> restore back to life my old Altair 8800 and any upgrade ideas you all may
--- In firstname.lastname@example.org, Chris Elmquist <chrise@...> wrote:
> also have a 6809 project which adds a coprocessor to a Z80 base platform
To add to this: the N8VEM 6809 board can also run as a stand-alone machine, running Cubix with a full toolchain. I've got one - highly recommended. It can even be expanded with a backplane. In fact, I like it so much I made a page for it here:
> It's not legacy but maybe more available ...
It's half legacy: new board but all vintage components :)