Chuck(G)
25k Member
I'd have to dig a bit, but I think I have a S.D. Systems Z80 card that has the connector (as a DIP socket, so it requires an adapter) that works just fine.
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Altair 8800 with Z80 CPU wont toggle anything. Help!!
- Thread starter k1atn
- Start date
Marty
Veteran Member
Hi All;
Chuck, If it is an SD Z-80 card the it never had a Front Panel connector.. I had one in the Past, I don't have it any more.. So, it must be something else besides an SD Z-80 Board to have that connector.. But Thanks for replying..
THANK YOU Marty
Chuck, If it is an SD Z-80 card the it never had a Front Panel connector.. I had one in the Past, I don't have it any more.. So, it must be something else besides an SD Z-80 Board to have that connector.. But Thanks for replying..
THANK YOU Marty
k1atn
Experienced Member
IC's "U","X","R","J","T", and "S" are socketed the rest are soldered directly. I will check the 7405's and get back to you.
Marty
Veteran Member
Hi All;
K1Atn, OK, It looks like someone has done some work on the Front Panel Before..
THANK YOU Marty
K1Atn, OK, It looks like someone has done some work on the Front Panel Before..
THANK YOU Marty
S.D.Systems S-100 Check
S.D.Systems S-100 Check
UPDATE: The original Z80 board, "Z8800 CPU CARD", sold as S.D.Sales in 1976 (designed by Micronix), was pitched as a board replacement for the Altair and IMSAI. The assembly instructions say, "If you have an Altair, install the white molex connector into the special holes in the upper right hand corner of the Board, A 16 pin socket is provided to the left of the molex connector for IMSAI computers". There may be other mods to use it with an IMSAI.
SDSales Z8800: http://maben.homeip.net/static/S100/sdsystems/cards/SDS Z8800 Z80 CPU Card.pdf
However the manual is among the worst I've seen (at least in English) but they did nicely include a few page tutorial on how to solder. The schematic is incomplete, listing only the S100 connectors and not showing the front panel connectors at all; just a note on the Z80 data lines "front panel".
S.D.System boards on my desk:
SBC-300
VFW-III Prototype
RomDisk (with serial port)
RamDisk
SBC-200 Rev C (two of them)
I/O-8 (8 serial ports)
S.D.Systems S-100 Check
I pulled out my S.D.Systems boards and visually confirmed that at least the SBC-200 and the SBC-300 neither had that front panel connection. If they once did, it would be on the 1977/76 board set. I'll check my documentation.Marty said:
UPDATE: The original Z80 board, "Z8800 CPU CARD", sold as S.D.Sales in 1976 (designed by Micronix), was pitched as a board replacement for the Altair and IMSAI. The assembly instructions say, "If you have an Altair, install the white molex connector into the special holes in the upper right hand corner of the Board, A 16 pin socket is provided to the left of the molex connector for IMSAI computers". There may be other mods to use it with an IMSAI.
SDSales Z8800: http://maben.homeip.net/static/S100/sdsystems/cards/SDS Z8800 Z80 CPU Card.pdf
However the manual is among the worst I've seen (at least in English) but they did nicely include a few page tutorial on how to solder. The schematic is incomplete, listing only the S100 connectors and not showing the front panel connectors at all; just a note on the Z80 data lines "front panel".
S.D.System boards on my desk:
SBC-300
VFW-III Prototype
RomDisk (with serial port)
RamDisk
SBC-200 Rev C (two of them)
I/O-8 (8 serial ports)
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Marty
Veteran Member
Hi All;
I looked at the Z8800 and it Does Definately has the Connector for an Altair Front Panel..
So, Chuck G, may be correct, if it is the later SBC 100 and SBC 200 than they Do not have this connector..
The difference between the SBC 100 and SBC 200 is the speed that the processor is running at..
Thank You J Dallas for straightening me out, I had not seen or heard of the Z8800 before.. I will look at the schematic, later..
THANK YOU Marty
I looked at the Z8800 and it Does Definately has the Connector for an Altair Front Panel..
So, Chuck G, may be correct, if it is the later SBC 100 and SBC 200 than they Do not have this connector..
The difference between the SBC 100 and SBC 200 is the speed that the processor is running at..
Thank You J Dallas for straightening me out, I had not seen or heard of the Z8800 before.. I will look at the schematic, later..
THANK YOU Marty
The Cromemco ZPU board also supports Altair and IMSAI... I've added the URL for the ZPU manuals below. They provide the socket for the IMSAI directly and show how to modify the Altair cable. That might help (I thought you were using a Cromemco... maybe someone else?)Marty said:
Cromemco ZPU 1977: http://maben.homeip.net/static/S100...Z80 Central Processing Unit 023-0012 1977.pdf
Cromemco ZPU 1978: http://maben.homeip.net/static/S100...0 Central Processing Unit 023-0012 197809.pdf
Cromemco ZPU 1980: http://maben.homeip.net/static/S100...0 Central Processing Unit 023-0012 198001.PDF
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Marty
Veteran Member
Hi All;
J Dallas, I think I have a Cromemco Z-80 Board, even though I can't find it at the present.. I can't say for sure whether I have it or not anymore..
I do have the Dual 68000/Z-80 Processor Board, and I don't see any place for a connector on it.. And I don't expect one..
See If this Schematic is any better..
http://www.s100computers.com/Popups/PU-Schematic-SDSystems-Z8800-CPU.htm
THANK YOU Marty
J Dallas, I think I have a Cromemco Z-80 Board, even though I can't find it at the present.. I can't say for sure whether I have it or not anymore..
I do have the Dual 68000/Z-80 Processor Board, and I don't see any place for a connector on it.. And I don't expect one..
See If this Schematic is any better..
http://www.s100computers.com/Popups/PU-Schematic-SDSystems-Z8800-CPU.htm
THANK YOU Marty
MikeS
Veteran Member
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Same poor schematic with a undocumented modification penciled in.Marty said:
My URL goes to the manual and the schematic is the very last page. Not a great piece of drafting.
I'm not surprised S.D.Systems dropped front panel support after that board, I was however surprised that Cromemco supported them so long, must have been a market share they won. My Cromemco ZPU card was included in my Cromemco Z-2 system bought in 1978. Nothing else in that system is Cromemco designed.
I didn't need a front panel because the ZPU jump to a selectable EPROM address on power-up and that was configured to address my Mini-Term MERLIN display EPROM. So when I powered up I got that command monitor and could enter code in hex; a nice simplification.
That MERLIN was a lot of fun... I had the Super Dense Graphics daughter card that gave it a whopping 300x200 B&W graphics pixels! At the time that was the best you could get. After I got a North Star MDS drive, I bought their GWBasic which was impressive.
By the time dual processor boards were being made, the inclusion of a Altair-Imsai panel support would have been unthinkable; that doesn't mean someone didn't do it. We certainly didn't do it at S.D.Systems, if fact we punted on the whole Z80-8088/6 idea after first me, then my boss studied it.
The only Dual processor board S.D.Systems offered was from a foolish acquisition and those cards were a mess - the designer at the acquired company didn't include enough power regulation and heatsinking. I discovered that and our V.P.Engr advised the executive staff who then all voted down the acquisition proposed by the company president.
A week later the president acquired the company anyway. The V.P.Engr quoted the president as justifying it by saying, "Silicon Valley engineers have to be smarter than plain old Dallas engineers. He wasn't so lucky and the computer division was sold a year later. We can only speculate on the reasons.
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k1atn
Experienced Member
Marty, I got your Eprom. How exactly do I ground pin 21, if i'm going to ground it to another IC which other IC would be best and what pin do I ground it to. do i just solder a wire to pin 21 of the Eprom after i bend it out, and then solder the other end of the wire to whatever pin on whatever IC? BTW i haven't checked those 7405's yet but when i do i will get back to you on it.
Marty
Veteran Member
Hi All;
K1Atn, Good !
Yes, Bend out pin 21, careful You don't Break it, and attack a Small wire to it, and the other end of the wire to pin 12 of the Eprom.. WithOUT bending out pin 12 and not getting solder on the Part of the pin that goes into the socket..
Wire-Wrap wire works best for this, Wire-wrap wire can be obtained from Radio Shack, If you don'r have any, Black or Blue would be fine if they have it.. As I like to use their Black for ground, and Red for Power and any other color for other things..
THANK YOU Marty
K1Atn, Good !
Yes, Bend out pin 21, careful You don't Break it, and attack a Small wire to it, and the other end of the wire to pin 12 of the Eprom.. WithOUT bending out pin 12 and not getting solder on the Part of the pin that goes into the socket..
Wire-Wrap wire works best for this, Wire-wrap wire can be obtained from Radio Shack, If you don'r have any, Black or Blue would be fine if they have it.. As I like to use their Black for ground, and Red for Power and any other color for other things..
THANK YOU Marty
k1atn
Experienced Member
i did that, and it's now at least trying to read from the onboard ROM, but MREQ (pin 69 on the bus as stated in the Z80 manual) is not connected to anything on the bus according to my altair manual so it is therefore inactive and according to the Z80 manual, if MREQ is inactive, U9's output will be high, disabling the ROM. when i start up the unit, the ROM led flickers and goes out, and when i turn off the unit it flickers again and goes out.
Marty
Veteran Member
Hi All;
K1Atn, Good Progress, when I look at the Schematic (which I am having trouble reading as well), On page 13 of the Manual, it says MReq is pin 65 and is used by Some memory Boards.. And I don't seem to be able to find pin 69 in the manual schematic, could be my bad eyes..
But, there is a Three pin Jumper that is used to attach the Rom U9 pin 12 to the Eprom pin 18.. Try this Completely Remove the Jumper and with Your scope look at in 18 on the Eprom and see IF it goes low, If it does try it and see If You are getting data out from the Eprom.. If not, Temporally attach a wire that is hooked to pin 18 of the Eprom, possibly (if their schematic is correct) the middle pin of the three jumper pins and Ground it, and see IF you get data out of the Eprom..
I Re-looked at the schematic and I saw pin 19 of the Z-80 CPU IC and that goes to two places one is Via a jumper to MREQ pin 65 thru a jumper, that If You followed my earlier instructions the jumper should be taken out.. Look at Your Memory Board and look for pin (Buss) 65 and see If it goes to anything.. It should be nothing, if it is an old memory board..
The other place that pin 19 goes to is MemWRT and that is fine.. So, you should be Ok there..
Also, the other thing to check, on Both Your Z-80 Board and Your Memory Board, is if there is Black Corrosion on the IC leads that are plugged into a Socket, If there is, then You may NOT be getting a good connection.. An INK Erasure will take care of cleaning the pins on the IC's.. Front and Back, not side to side.. I am going thru this on my Ithaca Audio Board right now..
THANK YOU Marty
K1Atn, Good Progress, when I look at the Schematic (which I am having trouble reading as well), On page 13 of the Manual, it says MReq is pin 65 and is used by Some memory Boards.. And I don't seem to be able to find pin 69 in the manual schematic, could be my bad eyes..
But, there is a Three pin Jumper that is used to attach the Rom U9 pin 12 to the Eprom pin 18.. Try this Completely Remove the Jumper and with Your scope look at in 18 on the Eprom and see IF it goes low, If it does try it and see If You are getting data out from the Eprom.. If not, Temporally attach a wire that is hooked to pin 18 of the Eprom, possibly (if their schematic is correct) the middle pin of the three jumper pins and Ground it, and see IF you get data out of the Eprom..
I Re-looked at the schematic and I saw pin 19 of the Z-80 CPU IC and that goes to two places one is Via a jumper to MREQ pin 65 thru a jumper, that If You followed my earlier instructions the jumper should be taken out.. Look at Your Memory Board and look for pin (Buss) 65 and see If it goes to anything.. It should be nothing, if it is an old memory board..
The other place that pin 19 goes to is MemWRT and that is fine.. So, you should be Ok there..
Also, the other thing to check, on Both Your Z-80 Board and Your Memory Board, is if there is Black Corrosion on the IC leads that are plugged into a Socket, If there is, then You may NOT be getting a good connection.. An INK Erasure will take care of cleaning the pins on the IC's.. Front and Back, not side to side.. I am going thru this on my Ithaca Audio Board right now..
THANK YOU Marty
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Marty
Veteran Member
Hi All;
After Cleaning the Black Crude from all of the Ic's that had it on them, and bending back in place two bent pins..
And Earlier taking out 4 wired in Jumpers of which I think were put in for a system that didn't have a Front Panel and putting pins in placed were jumpers were Hard wired, so they could be changed..
The Ithaca Audio Board works in my Altair, with the Front Panel..
THANK YOU Marty
After Cleaning the Black Crude from all of the Ic's that had it on them, and bending back in place two bent pins..
And Earlier taking out 4 wired in Jumpers of which I think were put in for a system that didn't have a Front Panel and putting pins in placed were jumpers were Hard wired, so they could be changed..
The Ithaca Audio Board works in my Altair, with the Front Panel..
THANK YOU Marty
k1atn
Experienced Member
Glad you got your board working, I will try to remove the jumper tomorrow, but I'm not entirely sure which jumper it is. is it labeled? I'm guessing it's the jumper labeled ROM enable?
I will try to remove the jumper tomorrow, but I'm not entirely sure which jumper it is. is it labeled? I'm guessing it's the jumper labeled ROM enable?Marty
Veteran Member
Hi All;
K1Atn, "" I'm guessing it's the jumper labeled ROM enable? "" I think so, but to be sure Just Ohm from the Eprom pin 18, to one of the pins for the Jumper.. (You've only got three choices) It should be one of them.. If You are at the correct Jumper..
THANK YOU Marty
K1Atn, "" I'm guessing it's the jumper labeled ROM enable? "" I think so, but to be sure Just Ohm from the Eprom pin 18, to one of the pins for the Jumper.. (You've only got three choices) It should be one of them.. If You are at the correct Jumper..
THANK YOU Marty
k1atn
Experienced Member
Hi everyone, I will check the jumper and do the other stuff when i can, I have some volunteer work that is taking a lot of my time right now. so i will get back to you all when i can.
Thanks.
Thanks.
Marty
Veteran Member
Hi All;
K1Atn, Thank You for letting us know.. Good for You that You have some Volunteer work..
I have been on pins and needles, waiting for Your response as to whether anything was working..
So, i'LL just have to be Patient and have some patience..
THANK YOU Marty
K1Atn, Thank You for letting us know.. Good for You that You have some Volunteer work..
I have been on pins and needles, waiting for Your response as to whether anything was working..
So, i'LL just have to be Patient and have some patience..
THANK YOU Marty
k1atn
Experienced Member
I just thought I'd give an update, but it doesn't look good for right now. I haven't had time to work on the Altair as of late, due to volunteer work becoming work work. So I'll just have to play it by ear for now. I'll let you know when I'm working on it again, but the only thing new with it is possible PS filter capacitors going bad because when i powered it up a few days ago, with a techtroniks 485 oscilloscope attached to the capacitors when i power up the the Altair, the ripple is there for about 2 seconds and then it goes to a gradual but quick flat line with and without the unit under load.
--Jean-Luc--
--Jean-Luc--