Something Went Wrong when I ReBOOTed ...

[Walt Perko]

Hi,  

I was testing DAZZLER programs on my ZAltair Z80c computer.  When it got hung-up I went to ReBOOT the computer and this is the current state of the machine.  

First comes the RESET:  

Then is the EXAMINE F800h:  

I can't seem to see that address F800h and IF I try RUN, the computer doesn't BOOT.  

So I try EXAMINE 0000h:  

The I tried to DEPOSIT 063 Octal:

Then 307 Octal DEPOSIT NEXT:  

Did something on the Don Caprio mini-FP fail?  Is this symptoms of something else?  

.

[Patrick Linstruth]

Have you tried removing and reinserting your cards?

I would suspect a motherboard/cable issue before an FP failure.

On Aug 10, 2026, at 4:39 PM, Walt Perko <r4r...@gmail.com> wrote:

Hi,  

I was testing DAZZLER programs on my ZAltair Z80c computer.  When it got hung-up I went to ReBOOT the computer and this is the current state of the machine.  

First comes the RESET:  

<IMG_9979-20260810-ZAltair Z80c RESET-c2K.jpg>

Then is the EXAMINE F800h:  

<IMG_9980--20260810-ZAltair Z80c Examine-c2K.jpg>

I can't seem to see that address F800h and IF I try RUN, the computer doesn't BOOT.  

So I try EXAMINE 0000h:  

<IMG_9981-20260810-ZAltair Z80c Examine-c2K.jpg>

The I tried to DEPOSIT 063 Octal:

<IMG_9984-20260810-ZAltair Z80c Deposit-c2K.jpg>

Then 307 Octal DEPOSIT NEXT:  

<IMG_9985-20260810-ZAltair Z80c Deposit Next-c2K.jpg>

Did something on the Don Caprio mini-FP fail?  Is this symptoms of something else?  

.

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<IMG_9985-20260810-ZAltair Z80c Deposit Next-c2K.jpg><IMG_9984-20260810-ZAltair Z80c Deposit-c2K.jpg><IMG_9979-20260810-ZAltair Z80c RESET-c2K.jpg><IMG_9981-20260810-ZAltair Z80c Examine-c2K.jpg><IMG_9980--20260810-ZAltair Z80c Examine-c2K.jpg>

[Walt Perko]

Hi, 

The second photo I posted shows when I try to EXAMINE F800h the LEDs are not showing the Martin Eberhard 88-2SIOJP ROM starting address or DATA LEDs ... The RAM is on the FDC+ board, so I don't understand why the F800h RAM address doesn't get selected to light up the Martin Eberhard 88-2SIOJP ROM LED data.  

Why would the backplane go bad?  The motherboard doesn't move, has no active part of operation other than the connections from board to board.  None of the cables haven't moved either.   

The only things that have moved since the computer was setup are the front panel switches once in a while when I need to ReBOOT the computer.  

At first, I thought perhaps it was some chip overheated so I turned the computer OFF for more than 24-hours, but that doesn't seem to be the problem.  Now I'm thinking maybe a chip died ... maybe on the Don Caprio mini-FP board since the EXAMINE and DEPOSIT functions are not working.  The history of the Don Caprio mini-FP boards is not so great.  

The Don Caprio mini-FP board is bolted to the front of the computer cabinet, so it cannot move ... the 16-PIN DIP to 16-PIN DIP cable is factory made and cannot move along with the other boards inside the computer.  

.

[Patrick Linstruth]

Why would a chip go bad?

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/ca941a34-950c-4f8b-a259-b4205ab6cb14n%40googlegroups.com.

[Walt Perko]

Hi, 

IF a chip overheats ... it might just stop until cooled ... but I would also think the heat might kill the chip too.  That's just my guess ... a chip maybe failed manufacturers tests and was sold as a "Grey Market" component.  Then it lasted until the other day.  

.

[Walt Perko]

Hi, 

The primary problem is that the computer cannot EXAMINE F800h ... is that a failure on the Martin Eberhard 88-2SIOJP board or the Don Caprio mini-FP board or the TDL ZPU/CPU board?  

.

[Patrick Linstruth]

Hard to know. All Examine does is inject a JMP (3C) and then the address set on the switches causing the CPU to change its program counter to the jump address.

Based on your picture, that isn’t happening because the Address lights don’t show F800 after Examine.

The address bus is set by the CPU, so the 2SIOJP shouldn't have anything to do with Examine.

I think we’ve seen this problem before and moving your cards around fixed it. Cheap and easy to try. If it doesn’t fix it or cause the symptoms to change, it didn’t cost anything.

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/ff5521d7-5934-42d1-b7db-1684272cb00cn%40googlegroups.com.

[Patrick Linstruth]

Sorry… typo… JMP is (C3).

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/273B875F-EF77-4EF3-B394-83DCFBE1D5BC%40deltecent.com.

[Walt Perko]

Hi,  

Those problems were on a different backplane.  This computer has been working for a year or so exactly as it is now.  

I did try moving the ZPU board to another slot, then I moved it back and moved the FDC+ and the 88-2SIOJP boards to different slots ... nothing changes ... 

This is what I see on my TeraTerm screen:  

.

[Walt Perko]

Hi,  

I replaced the reproduction of the original DAZZLER board set with another and things seem back to normal ... but I'm trying to connect an 88-2SIOR1 Port 0 address 16H/17H to another computer with an 88-2SIOR1 Port 0 address 14H/15H at 9600 BAUD ... This is what I'm getting from my test program sending the alphabet:  

A0>DTERM4
WANT LOOPBACK TYPE L?
CTL PORT ADDRESS ? 22
��������������������������������������������������������������������������������
�����������������������������������������������

On the TeraTerm screen it's just squares ... they're coming in at 9600 BAUD no problem ... just not looking like an alphabet.  

Does anybody know why the characters are squares and not ASCII letters?   Is this a bit being dropped somewhere?  or maybe the 88-2SIOR1 in my ZAltair Z80c computer got scrambled by the DAZZLER test program while it killed my DAZZLER board set?  The test program was trying to use that same serial port.  

.

[Walt Perko]

Hi, 

Solved this latest conundrum ... from pulling and inserting boards OUT/IN to the computer I had bumped the BAUD rate DIP switch ... got it set back to 9600 BAUD and the two computers are now communicating between each other properly again.  

.