The Apple-1 Software Library ^Beta

Browse all the Apple-1 programs that ever existed. A tribute to history and their hackers.
Run them in any emulator, or instantly on the (real) machine.

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Dis-Assembler

by Steve Wozniak, Allen Baum in 1976

Shows the mnemonic form of the 6502 instructions that are in memory.

apple tapeassemblywithin 4k

Sold by Apple Computer on cassette tape for $5, order code A1T008X.

History

In the article A 6502 Disassembler from Apple this program was published in Dr. Dobb's Journal of Computer Calisthenics & Orthodontia by Steve Wozniak in 1976. It outlined its features and comes with the assembly source listing.

Description

As given in the article:

This subroutine package is used to display single or sequential 6502 instructions in mnemonic form. The subroutines are tailored to disassemblers and debugging aids, but tables with more general usage (assemblers) are included. ...

Features

Four output fields are generated for each disassembled instruction:

Address of instruction, in hexadecimal (hex).

Hex code listing of instruction, 1 to 3 bytes.

Three-character mnemonic, or ??? for invalid ops (which assume a length of 1 byte).

Address field, in one of the following formats.

Address format example Address Mode

(empty) Invalid, Implied, Accumulator

$12 Page zero

$1234 Absolute, Branch (target printed)

#$12 Immediate

...

Address format example	Address Mode
(empty)	Invalid, Implied, Accumulator
`$12`	Page zero
`$1234`	Absolute, Branch (target printed)
`#$12`	Immediate

Instructions

The program can be used to disassemble machine code that resides in memory. To set the begin address, the PCL ($44) and PCH ($45) zero page variables can be used.

For example, use the following Wozmon commands to disassemble the first 20 instruction of BASIC (make sure it is loaded first at E000):

44: 00 RETURN to set the low nibble of the address (E000).
44: E0 RETURN for the high nibble (EO00).
800R RETURN to run the dis-assembler.
R RETURN run again, to displays the next 20 instructions.

For more details see the article in Dr. Dobb's.

References

Dr. Dobb's Journal of Computer Calisthenics & Orthodontia (September 1976, vol. 1, no. 8, p. 22-25), where this program was published.
6502 Quick Reference on Mike Willegal's Apple-1 Quick Reference sheet (second page).

Serial

Wozmon Binary

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Dr. Dobbs Journal

Public Domain

Last update:
3 October 2024

Source: Wozmon

Target: Apple-1

Auto start

Ends the listing with the run command like xxxR, so the program is started directly after transfer.

TurboType™

Increased transfer speed combined with an integrated CRC check. Displays EE in case of a CRC failure.

Disconnected

Start — End	Size
`E000` — `EFCD`	3.95 KiB

Total net size is 3.95 KiB, or 4046 bytes.

Program starts with E000R RETURN.

Auto start

Ends the listing with the run command like xxxR, so the program is started directly after transfer.

TurboType™

Increased transfer speed combined with an integrated CRC check. Displays EE in case of a CRC failure.

Historical reference : hardware

In 1976, the Apple-1 Computer was advertised for $666.66 and came with 4K of on-board memory. For a $120 extra, this doubled to 8K of RAM. The provided Operation Manual included the circuit diagram and assembly code of the monitor program.

The Cassette Interface (or ACI) was used to load and save programs from cassette tape. The ACI Manual showed how to install it (the main board had to be jumpered correctly) and explained how it had to be used. Priced at $75, it included a cassette of Apple BASIC.

Software

Its BASIC was written by Woz himself. It did not support floating point arithmetic, but was tiny enough to fit in 4K of memory. The software itself was free. The Preliminary Apple BASIC Users Manual explained how to write your own games and programs with it.

Cassette tapes could be bought as an original accessory to your new Apple-1. A total of nine programs were available and listed $5 each. Pick one below and go back in time.

BASIC Mastermind Lunar Lander Blackjack Hamurabi Mini-Startrek 16K-Startrek
Dis-Assembler Extended Monitor

At the time, people were also inspired by publications like 101 BASIC Computer Games. They spent their evenings and nights to key-in the games, but soon were disappointed to discover that some of these did not work at all because of the missing floating points... Arghh.

Dive deeper? Read more here and here.

How to emulate?

It is easy to run the software with one of these emulators:

Apple 1js, right here in the browser
Pom1 ported to C (also for Android)
Green Delicious for the C-64
Emulation framework MAME
WOZNIAC-1 for iOS

View a comparison of emulators here.

...and run a program

First, start the emulator of choice and have it run Wozmon (or BASIC), then use the Wozmon button to copy-paste the program code into the emulator.

For example: open Apple 1js in another browser tab. Hit CLS to clear the screen and RESET to enter Wozmon. Then paste the copied Wozmon code from this website.

In-website transfer to an Apple-1 ^{Available soon}

This website can connect directly (and locally) to the Keyboard Serial Terminal from 8BitFlux.com. It uses the Web Serial API for this and is supported by Chrome or Edge browsers. The Wozmon code of any program can be transferred quickly.

The Keyboard Serial Terminal connected to an Apple-1.

Use the Serial button to transfer the current program to the Apple-1. For example, BASIC takes around 20 seconds to transfer at a speed of 57.6 kbps. The board is compatible with the higher-speed TurboType™ format (with CRC check).

After the transfer of the game or program, switch over to the normal Apple-1 keyboard (by pressing a button) and enjoy it. This makes also a great kit for museums and public events. Kits available soon »

Further exploration

Talk on Applefritter, the home ground of the Apple-1 Owners Club.
The Apple-1 Registry keeps track of all real Apple-1 machines that ever existed.
The story of a homebrew Apple-1 computer by Bryan.
Vince Briel's GitHub repository has all the information on his Replica 1.
P-Lab lists interesting Apple-1 projects on his website.
San Bergman's website has a lot of well-documented information on the Apple-1, from its internal workings to programming it in assembly.
Take the online course in 6502 assembly language programming.

Credits

This library is an initiative of 8BitFlux.com. It can be put to full use with a Keyboard Serial Terminal adapter board, which let you run software instantly on a (real) Apple-1.

Many thanks to Uncle Bernie for his support and provision of his TurboType™ algorithm, which is part of his Apple-1 Toolchain.

Last but not least, all this was not possible by all the authors of Apple-1 software and emulators. The hobby computer enthusiasts of the past, but also people of the present, who keep this hobby so alive. Thank you all.

Disclaimer

This website is not associated with Apple Inc. in any way.

It tries to be a tribute to (their) history. It wants to list only software that is already considered to be in the public domain, or its license permits further publication. The (online) sources of the program and other references are listed when known.

Mistakes happen, as this website is not generated by any AI, please report any nonconformities.

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The Apple-1 Software Library Beta