General Information
The SBC1802 was designed by Robert Armstrong in 2024. Here is a short overview from Bob’s Github page:
After building the Elf 2000 almost 20 years ago, I decided it was time for another 1802 based project. The primary goal of the Elf2K was to be as much like the original Elf as possible, however this time around the goals were entirely different.
My plan was to design a machine that
- could run both ElfOS and RCA MicroDOS
- used as many of the LSI RCA CDP18xx family chips as possible
- supported multiple peripherals and mass storage devices
I ended up splitting the design into two boards, a "base" board and an expansion board. Originally I planned to fit it all onto a single board but that ended up being too large and two boards, which can be stacked in the vertical dimension, are much more practical. The expannsion board is optional and the base board is functional without it. Also, the expansion bus is available for additional future, well, expansion.
Technical specifications
Clock: 2.5 Mhz
Memory:
64 KB SRAM
32 KB ROM
Video: None
Sound: Two AY-3-8912 PSGs
Keyboard: A PS/2 keyboard with an AT89C4051 auxiliary processor to decode the PS/2 prototocol to generate ASCII key codes.
Screen shot
Screen shot on the right is an SBC1802 booting MicroDOS from a TU58 disk image using a VT100 terminal.
Links
Other information about the SBC1802:
- Bob’s SBC1802 GitHub
Main Features SBC1802 Emulator
- Adjustable speed, boosting the speed of the SBC1802 beyond 2.5 Mhz
- SBC1802 Front Panel
- Support for the CDP1877 priority interrupt controller
- Support for the CDP1879 real time clock with ‘battery’ backup
- Support for 2 IDE disk drives
- Support for 2 TU58 ‘drives’ connected a via CDP1854 UART
- Support for RCA style two level I/O
- Support for CDP1851 programmable I/O interface
- Support for CDP1878 dual counter/timer
- Support for two AY-3-8912 programmable sound (aka music) generators
- Automated XMODEM support
- Direct SBC1802 memory access to load and save software from the PC hard disk via bin or hex files
- Video screen dump to a file (BMP, JPEG, PNG or PCX image)