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D. Loading and Using Disk BASIC from Floppy Disk
In this demonstration, we will boot and use Altair Disk BASIC version 5 (spe-
cifically version 300-5-F).
Computer Configuration
Serial port 1 on the Altair Clone (the upper DB-25 connector) should be
configured as a 2SIO serial port at octal I/O address 20/21. This port
serves as the operator’s terminal. This is a standard Altair configura-
tion. This is also the default Altair Clone configuration for port 1. You
can confirm or change the Clone’s serial port configuration if needed. See
“Serial Port Menu” in Part 2, “Configuration Monitor” of this manual.
To boot a floppy disk, the “Disk Boot Loader” (DBL) PROM was typically in-
stalled in the Altair. Refer to the “PROM Menu” section in Part 2, “Con-
figuration Monitor” to see if this PROM is already installed in the Clone.
If not, follow the instructions to “Load New PROM Content” and install the
.hex file “ROMS\DBL.HEX” into one of the empty PROM slots.
Follow the “Insert Floppy” instructions in the “Floppy Disk Menu” section
of Part 2, “Configuration Monitor” to insert the floppy image “BA-
SIC\Floppy Disk\Games on 300-5-F.dsk”. Either load the floppy directly
into drive 0, or use the “Change Drive Assignment” menu option after up-
loading to assign the floppy to drive 0. Once you have uploaded the flop-
py, you do not need to repeat this step unless you over-write the floppy
with other content.
Follow these steps to boot Altair BASIC from floppy disk:
1) Turn the power switch on.
2) Raise and hold the STOP switch in the STOP position, then raise and re-
lease the RESET switch. Finally, release the STOP switch. This performs
a hard reset on the computer and sets all address lights to zero.
3) Set switches A15-A8 to the up position (one) and switches A7-A0 to the
down position (zero). This represents the start address of the Disk
Boot Loader (177400 octal or FF00 hex).
4) Raise the EXAMINE switch to load this address into the processor.
5) Set switches A15-A13 to the down position. This leaves the first four
switches (A15-A12) set to 0001. This tells BASIC the console terminal
is connected to a 2SIO board with one stop bit.
6) Depress the RUN switch to boot the Altair from the BASIC floppy.
7) In response to the “MEMORY SIZE” prompt, press RETURN to let BASIC de-
termine the amount of RAM present.
8) In response to the “LINEPRINTER” prompt, key in “O” (capital letter
“oh”) and press RETURN.
9) In response to “HIGHEST DISK NUMBER” key in “2” and press RETURN.
10) In response to “HOW MANY FILES” key in “4” and press RETURN.
11) In response to “HOW MANY RANDOM FILES” key in “4” and press RETURN.
At this point, Disk BASIC is up and running! You can type an immediate com-
mand like “PRINT 2+2” and press RETURN. BASIC will display the answer, 4. In
this version of BASIC, the backspace key performs the normal “destructive
backspace” to which you are accustomed.
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