Differences ??? 8080 v. Z80 ???

[Walt Perko]

Hi,  

Here's a conundrum:  

The program works exactly as expected on the Altair 8800c computer, but fails on the ZAltair Z80c computer ... all the same boards in both machines other than an 8080 or Z80 CPU board.  

Running this program on the ZAltair Z80c computer with a SSM CB2 Z80 CPU board:  

A1>MBASIC PASCALT3
BASIC-80 Rev. 5.21
[CP/M Version]
Copyright 1977-1981 (C) by Microsoft
Created: 28-Jul-81
21048 Bytes free
TERMINAL WIDTH, 80 OR 132? 132
STARTING NUMBER? 512
                                                                512
                                                               512512
                                                             5121024512
                                                           51215361536512
                                                         512204830722048512
Illegal function call in 1140
Ok
RUN
TERMINAL WIDTH, 80 OR 132? 80
STARTING NUMBER? 1
                                       1
                                       11
                                      121
                                     131)1
                                    1413111
Subscript out of range in 280
Ok
RUN
TERMINAL WIDTH, 80 OR 132? 80
STARTING NUMBER? 512
                                      512
                                     512512
                                   5121024512
Subscript out of range in 200
Ok

Now running the same program on the Altair 8800c computer with a Reproduction MITS 8080 CPU board:  

A1>MBASIC PASCALT3

BASIC-80 Rev. 5.21
[CP/M Version]
Copyright 1977-1981 (C) by Microsoft
Created: 28-Jul-81
21048 Bytes free
TERMINAL WIDTH, 80 OR 132? 132
STARTING NUMBER? 512
                                                                512
                                                               512512
                                                             5121024512
                                                           51215361536512
                                                         512204830722048512
                                                       5122560512051202560512
                                                    512307276801024076803072512
                                                 5123584107521792017920107523584512
                                              512409614336286723584028672143364096512
                                            51246081843243008645126451243008184324608512
                                        5125120230406144010752012902410752061440230405120512
                                     5125632281608448016896023654423654416896084480281605632512
                                 512614433792112640253440405504473088405504253440112640337926144512
                              512665639936146432366080658944878592878592658944366080146432399366656512
                        51271684659218636851251210250241537536175718415375361025024512512186368465927168512
                     512768053760232960698880153753625625603294720329472025625601537536698880232960537607680512
                 5128192614402867209318402236416410009658572806589440585728041000962236416931840286720614408192512
            512870469632348160121856031682566336512995737612446720124467209957376633651231682561218560348160696328704512
       5129216783364177921566720438681695047681629388822404096248934402240409616293888950476843868161566720417792783369216512
  51297288755249612819845125953536138915842579865638697984472975364729753638697984257986561389158459535361984512496128875529728512
Ok
RUN
TERMINAL WIDTH, 80 OR 132? 80
STARTING NUMBER? 512
                                      512
                                     512512
                                   5121024512
                                 51215361536512
                               512204830722048512
                             5122560512051202560512
                          512307276801024076803072512
                       5123584107521792017920107523584512
                    512409614336286723584028672143364096512
                  51246081843243008645126451243008184324608512
              5125120230406144010752012902410752061440230405120512
           5125632281608448016896023654423654416896084480281605632512
       512614433792112640253440405504473088405504253440112640337926144512
    512665639936146432366080658944878592878592658944366080146432399366656512
Ok

[Walt Perko]

Hi, 

I found another odd thing with the ZAltair Z80c computer:  

9-Slot backplane board  

Don Caprio mini-FP (Front Panel) board  

SSM CB2 Z80 CPU board  

88-2SIOJP board (Console and ESP FDC+ WiFi Serial Disk Server)  

88-2SIOR1 addressed 14h/15h and 16h/17h  

Reproduction DAZZLER board set  

88-2SIOR1 Port 0 14h/15h connected to a USRobotics v.92 modem  

I can never get any "ECHO" of AT commands from the modem when I type them in.  I can see the Rx/Tx LEDs on the modem blinking.  

I swapped the DB25 (modem side) to DE9 (88-2SIOR1 side) cable with the working cable on my Altair 8800c computer, but it's still the same problem.  

I then just moved the v.92 modem and cable over to the Altair 8800c computer and everything works just fine.  I see all my AT commands on the console.  

So, I swapped the DTC cable from the 88-2SIOR1 to the back of the computer with another new one from Patrick.  Still didn't work.  

So, I swapped out the 88-2SIOR1 board with a new one from Patrick and still it's the same problem!  

Bottom line, could it be something is not right with the SSM CB2 Z80 CPU board?  

.

[Walt Perko]

Hi, 

or ... perhaps it's the Don Caprio mini-FP board ... I tried three other known good working ZPU boards and none of them worked in the computer ???  Now I'm back to the TDL ZPU Z80 CPU board (my mistake the SSM CB2 is in another computer and another in my stash.)  

The pair of boards were those that came back from repair ... somehow he managed to get them to work together now knowing there was something else wrong with the board set.  

.

[Patrick Linstruth]

If the TX light on the modem blinks when you transmit and the RX light doesn’t blink, it means your modem is configured to not echo commands.

Those TX and RX lights are there for a reason. If the TX light on your modem never blinks, then the modem is the first place to start.

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[Patrick Linstruth]

Sorry, got that backwards. If the RX light on your modem blinks, it is receiving characters. If the TX light doesn’t blink, it is not echoing them, which could mean it’s programmed not to echo, which is probably the case if it was used with CBBS.

It could also be set up to ignore commands if DTR is low. If the DTR light is ON, that’s not an issue.

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/E520E91E-2AE3-4BB4-A312-4616C075ADB2%40deltecent.com.

[Walt Perko]

Hi,

All the LEDs are blinking … when I type anything on the console, both the Rx and Tx LEDs on the modem flicker. 

Everything works other than getting that echo or receiving any data from the modem to the console. 

Even when I dial into a BBS, I don’t see anything on the console although the remote BBS has connected. 

I captured a couple of sessions on video ... 

.

[Patrick Linstruth]

Is the 2SIOR1 DCD switch ON?

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/8626c50e-fab1-4818-8c28-6ca6029fe05en%40googlegroups.com.

[Patrick Linstruth]

Walt, let’s make this easy. Put a jumper between pins 2 and 3 at the end of the cable that plugs into the modem. That will loop TX back to RX.

If you still don’t get any echo, time to look elsewhere.

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/94E52BDB-306F-4D42-8B42-007DE78FB4EA%40deltecent.com.

[Patrick Linstruth]

If that doesn’t work, jumper pins 3 and 5 on the 2SIOR1 IDE connector and see if that changes anything.

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/E6E5E858-9735-46D7-9AFD-8D5346C3577A%40deltecent.com.

[Walt Perko]

Hi,  

Seems the cable connecting my Altair 8800c and the Port 0 of the ZAltair Z80c computer was causing the problem.  As soon as I removed that cable, everything started working correctly.  

.