Here's an oddity ...

Walt Perko

unread,

Apr 20, 2026, 12:50:08 PMApr 20

to Altair 8800

Hi,

My ZAltair Z80c: https://www.brainless.org/Altair/OakZAltair8800c/

It won't BOOT to CP/M when I try a "B" at the AltMon prompt, but when I typed an "R" it BOOTed CP/M ... that's a neat trick to get around the "B" command failing.

A0>

I still find AMON a more user friendly monitor than ALTMON ...

.

Peter Sterrantino

unread,

Apr 22, 2026, 9:21:08 AMApr 22

to Walt Perko, Altair 8800

Hi Walt,

The "B" command jumps to FF00h (which is the typical default location for the Altair bootloader).

The "R" command jumps to FC00 (which is an alternate bootloader location). This is where ROMBOOT is located if using the serial server or FDC+ ESP32 setup.

I'm assuming you are using the latter which explains why it works.

Pete

--
You received this message because you are subscribed to the Google Groups "Altair 8800" group.
To unsubscribe from this group and stop receiving emails from it, send an email to Altair-8800...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/5de16563-7195-4f6f-9a2f-fbca639a60fcn%40googlegroups.com.

Walt Perko

unread,

Apr 22, 2026, 10:10:54 AMApr 22

to Altair 8800

Hi,

Odd thing is, the computer was BOOTing to CP/M with the "B" command until yesterday, but it's not a big deal, just odd.

.

Patrick Linstruth

unread,

Apr 22, 2026, 1:11:54 PMApr 22

to Altair 8800

Are you sure the “B” command was booting to Serial CP/M at not a disk attached to the FDC+ Serial Drive Server?

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/bba44742-dff6-44bc-91ae-82622d545884n%40googlegroups.com.

Reply all

Reply to author

Forward