retro-style computer that
functions like the Altair
and can run original, unmodified software. The
simplest Altair configuration that could run 4k
BASIC was the 8080A CPU board, at least 4K of RAM, and a serial IO
interface. The 6850 UART
was used in the 88-2SIO serial interface boards.
This project has evolved over time, resulting in a series of different
Version 1 is a minimal
hardware configuration that will run Altair BASIC
It consists of
an 8085 CPU, a RAM chip, a 6850 UART, a latch and some glue logic and a
PIC microcontroller. On power up the PIC loads the Altair
bootloader into RAM, then resets the 8085 and starts it running.
BASIC can then be loaded through the 6850 serial port.
2 adds a little more glue logic to allow the PIC to control the 8085
like an Altair front panel. It can perform the run/stop,
step, deposit, deposit next, examine and examine next functions.
Version 3 adds a floppy disk emulator using an SD card for storage.
The hardware emulator is register-compatible with the 88-DCDD
Altair Floppy Disk System. This allows all of MITS disk
software (disk BASICs and Altair DOS) to
run unmodified. The floppy data is
stored on the SD card using the FAT32 file system so disk images can be
easily transferred to other computer systems. The disk images
stored as files which are straight binary images of the floppies.
This is the same format as the Altair32 emulator so the
provided in the emulator can be used directly and exchanged between the
emulator and the Mini-Altair. With the disk emulator, the
Mini-Altair connected to a dumb terminal becomes a complete stand-alone
computer system without the need to ever connect to another computer in
order to operate.
Version 4 expands the RAM from 32K to 64K. This allows
versions of CP/M that are configured for more than 32K of RAM to run.
Rich Cini's Altair emulator. Not only is the
useful, but it includes all the different versions of Altair BASIC, the
bootloaders, the Turnkey PROM monitor, BASIC programs and more.
Geoff Harrison's excellent explanation of the boot process
with disassembly of the bootloader.
Grant Stockly's Altair 8800 kit.
Vince Briel's Briel Computers Forum where this
project got started.http://altairclone.com/
Mike Douglas' superb Altair 8800 replica. The support page has a
full selection of Altair software as well as CP/M.