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- Apple F.A.Q.
Quick Start User Guide for
the Apple One Computer
Quick User Guide for Apple
1 Computers
History and Trivia about the Apple
One
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See more pictures of the Apple One at the Photo
Gallery
The Apple 1 was a kit computer that was introduced
and sold in small quantities in 1976. Steve Wozniak
("Woz"), who worked for Hewlett-Packard
at the time, wanted to build his own computer.
He could afford neither the Intel 8080 (the most
popular microprocessor at the time) nor the Motorola
6800 (his own preference). Therefore, he decided
to build his computer around MOS Technology's
new 6502 chip, which was quite compatible with
the Motorola 6800 but far less expensive. He
proceeded to write a BASIC interpreter for the
chip, and then turned to designing the computer
that would run it, using an earlier paper design
for the Motorola 6800.
The resulting computer was easier to use and
more affordable than many other kit computers
of the time, sporting a keyboard interface and
TV-compatible video terminal circuitry, all on
a single circuit board. To keep costs down, the
video memory was implemented using shift registers
rather than RAM, with the downside being a slow
display rate (60 characters per second). However,
this was still much faster than the 10-character-per-second
electromechanical Teletypes used with many early
home computers. Wozniak's computer also used
new, more compact
4-kilobit dynamic RAM chips instead of the 1-kilobit
static RAMs used by most other designs. Wozniak
promoted his computer and enhancements for it
at the Homebrew Computer Club in Palo Alto, California.
Steve Jobs, who had worked with Woz on the game
"Breakout" for Atari, convinced Woz
to try to market and sell the computer. Together
they formed the Apple Computer Company. Paul
Terrell, the owner of The Byte Shop, a new local
computer store, was interested in this computer,
but only if it was fully assembled and came with
a cassette interface, so Wozniak designed one.
Normally, the Apple 1 was sold "naked",
simply as a circuit board, without a monitor,
power supply, keyboard, tape drive, etc. These
would be added by the owner. Wozniak and Jobs
assembled about 200 systems and sold about 170
of them. Most of these were later traded in to
Apple for Apple IIs and were destroyed. About
30 to 50 are still in existence.
Features:
CPU: MOS Technology 6502, 1 MHz
Memory: 4 kB DRAM,
expandable to 8 kB on board, or up to 52 kB with
third-party expansion hardware
Screen: 40x24 characters
Storage: Optional cassette interface
Usage of the Apple One Computer:
Upon boot or reset, the system displays a "\"
and a blinking "@" cursor on the next
line. The blinking "@" is the Apple
1's video cursor. The "\" is the prompt
for the
Monitor program. From the Monitor, you can examine
or change memory or execute another program.
You can always interrupt a program and return
to the Monitor by pressing the Apple 1's RESET
switch (F12). This will not clear the screen
or disturb memory contents.
To cold-boot the system, clearing the screen
and memory, press the MESS Reset key (F3, in
partial emulation mode only).
The Apple 1's CLEAR SCREEN switch (F2) will clear
the screen and place the cursor at the upper
left corner. This only clears the video hardware,
not the computer's memory, so you can use it
whenever you like.
To start the cassette interface's mini-monitor
from the Monitor, type the Monitor command:
C100R This mini-monitor will let you write memory
regions to a cassette image or read a cassette
image into memory. It will only execute a single
line of commands, and will then return you to
the main Monitor, but this line can contain several
write or read commands.
Cassette write command, writing data from memory
at $xxxx-$yyyy:
xxxx.yyyyW
Cassette read command, reading data into memory
at $xxxx-$yyyy:
xxxx.yyyyR
The starting and ending addresses xxxx and yyyy
should be 4-digit hexadecimal addresses. The
starting address can actually be shorter than
4 digits, but to be safe, the ending address
should be exactly 4 digits. (A bug in the cassette
mini-monitor will cause digits missing from the
ending address to be replaced by the trailing
digits of the starting address, and if the starting
address does not end with zeroes, much more data
will be written or read than expected.) If a
command line contains multiple write or read
commands, the corresponding memory regions will
be written or read in sequence. These commands
may be separated by spaces, which are ignored.
When a region is written, its data is preceded
by a 10-second leader. When a region is read,
the leader can vary in length but should be at
least 4-5 seconds. If the cassette image doesn't
contain enough data to fill a region, the mini-monitor
will hang waiting for the remaining data, and
the system must be reset. When all the cassette
commands have been executed, the mini-monitor
will return to the Monitor, which will display
a "\" prompt.
Some cassette command examples:
To read Apple 1 BASIC from cassette:
E000.EFFFR
To write a BASIC program to cassette,
with BASIC's default LOMEM= setting of 2048:
4A.00FFW800.FFFW
To read a BASIC program from cassette, with
LOMEM=768: 4A.00FFR300.FFFR
Once Apple 1 BASIC is loaded into memory,
it can be started with the Monitor command:
E000R
This will start BASIC from scratch, removing
any existing BASIC program and data.
To return to BASIC from the monitor while preserving
the current program and data, use the command:
E2B3R
The BASIC prompt is a ">". Apple
1 BASIC is generally similar to Apple II Integer
BASIC, but without the latter's graphics commands.
MESS Emulation State:
Optional cassette interface is included and
emulated.
4 KB of DRAM is mapped to $E000-$EFFF. This
is required for Apple 1 BASIC.
Known Issues:
The cassette interface and $E000-$EFFF DRAM
are always included; they cannot be switched
off. The DRAM at $E000-$EFFF is not included
in the RAM configured by MESS's -ram option,
due to limitations in how MESS presently manages
configurable RAM.
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