Problem after 'Restore Defaults'

General discussions related to the Altair 8800 Clone

Problem after 'Restore Defaults'

Postby mail@gabrielegan.com » June 10th, 2015, 3:25 am

I was trying to disable the PROMs (to give Timeshare BASIC its maximum RAM) when I found that even when 'disabled' the DBL was working. That is, running from 177400 octal did a disk boot even with the DBL PROM disabled. So I 'removed' the PROM entirely and tried again. Still the DBL was there! It seems that a power-off is needed to make it actually go away. In further testing, I tried a 'Restore Defaults' in the Admin menu to get everything back as it was when the Altair arrived. But in fact this doesn't restore the PROMs but does wipe the floppy drives.

Okay, so I'll reload the floppies from a PC. Unfortunately, this no longer works. I set the floppy load rate to 9600 baud (to make the terminal emulator I use) and tried an XMODEM transfer (128 byte blocks, CRC checksum) to reload the floppy, but for some reason this no longer works. I'd loaded floppies several times before this morning using these settings, so it looks like a 'Restore Defaults' has changed as subtle setting somewhere that I need to fix. Anyone know what it might be?

Regards

Gabriel Egan
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Re: Problem after 'Restore Defaults'

Postby AltairClone » June 10th, 2015, 10:54 am

Gabriel,

You are correct, a disabled or removed PROM doesn't actually disappear until power has been cycled. This is a side effect of having changes made in the Configuration Monitor not require a full power-on style initialization when exiting the monitor and returning to a previously running program. I should probably fix this or document it :)

"Restore Defaults" erases both floppy content and PROM content as stated in the warning/confirmation prompt.

For XMODEM transfers with the Configuration Monitor, use the checksum mode of XMODEM, not CRC.

Mike
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Re: Problem after 'Restore Defaults'

Postby mail@gabrielegan.com » June 11th, 2015, 11:50 am

Thanks Mike! I could swear that I didn't accidentally change CRC/checksum setting but from what you say I bet I did -- will try putting that back.

Regards

Gabriel
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Posts: 94
Joined: October 11th, 2014, 8:12 am

Re: Problem after 'Restore Defaults'

Postby mail@gabrielegan.com » June 16th, 2015, 1:40 pm

Just in case anyone else is as stupid as me, I'll mention what I was doing wrong . . .

Booting up Multi-User BASIC on my terminal emulator (CONEX running under DOS on an old 286) makes the BASIC start-up messages appear to flash on and off. I figured that this is because the terminal emulator is listening to all 8 incoming bits, and BASIC by contrast is expecting the terminal to ignore the 8th bit altogether (ASCII being a 7-bit code) and is putting out something untoward in that 8th bit that is throwing off the terminal emulator. I recalled that Mike explains this in relation to TeraTerm in one of the early videos--the BASIC start-up message being slightly corrupted--and advises switching TeraTerm to 7-bit mode. So, I did this for CONEX too, not realizing that in CONEX the 7-bit mode then also applies to XMODEM file transfers too. (I bet TeraTerm doesn't do anything so silly as that -- but CONEX is in many other regards really quite impressive software.)

So that's why I couldn't reload the floppy content: I was doing the file-transfers in 7bit mode!

I'm back on track setting up a 3-Altair, 9-terminal BASIC lab -- will post pictures, including a second Lear Siegler ADM that I just snapped up on Ebay.

Final question for anyone interested in ergonomics: am I mad to make this a standing-up-only lab rather than providing chairs? It's supposed to be healthier, and when I teach letterpress manual typesetting we all stand the whole time, so why not with computers?

Regards

Gabriel
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Posts: 94
Joined: October 11th, 2014, 8:12 am


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