apple1serial
This repository contains firmware files for the Apple-1 Serial Interface expansion card.
Description
This project aims to provide alternative to the ACI for the Apple-1 replica or original boards owners via use of the serial communication (9600/8-N-1). The project is based around ATMega328P MCU which operates as half-duplex UART.
Memory map
| address | function |
|---|---|
$C100 |
the original ACI loader program adapted to the A1SI |
$C300 |
"teletype on apple-1" test program - the data from remote terminal appears on Apple-1 screen |
$C400 |
"teletype on remote" test program - the data from Apple-1 appears on remote terminal |
$C500 |
0-255 repeating counter - all possible bytes are repeatedly sent to remote terminal |
$C600 |
serialmonitor - the well known Woz Monitor, but now on the remote terminal |
entries for programmers:
| address | function |
|---|---|
$C000 |
ready flag - contains 0x01 if the device is ready to write/read byte, 0x00 otherwise |
$C080 |
read address - the location for data read from the interface, first read of this address switches the device to read mode |
$C081 |
write address - the location for data to be written via the interface, first write to this address switches the device to read mode |
$C23A |
software reset routine - resets the MCU |
$C1EC |
block read routine - reads data from the interface to the specified address range |
$C213 |
block write routine - writes the data via the interface from the specified address range |
$0034 |
lower byte of the end address for block read/write routines |
$0035 |
upper byte of the end address for block read/write routines |
$0036 |
lower byte of the beginning address for block read/write routines |
$0037 |
upper byte of the beginning address for block read/write routines |
Contents
The contents of this repository are as following:
- firmware/ - contains source code for the ATMega328 MCU firmware
- mapping/ - contains EQN and JED files for GAL20V8 based address decoder for the board
- src/ - contains the 6502 assembly sources for the A1SI onboard ROM routines
Requirements
You need the following to successfully build the firmware:
- xa cross assembler
- avr-gcc toolchain
- avr-libc set of libraries
- AVRDUDE AVR programmer software or equivalent
- Some software capable of translating the EQN files into JED's. I used for this purpose the DOS based EQN2JED from OPALjr PLD Development Package.
How to build?
To build the firmware just type:
make
And to clean the build:
make clean
PCB
The KiCad project files with board design and schematics can be found here:
http://github.com/flowenol/Apple1SerialPcb
Applesoft BASIC support
You can also LOAD and SAVE your Applesoft BASIC programs thanks to the branch of the
applesoft-lite project which has been modified to make use of the A1SI expansion card: