The SC111, Z180 CPU module, houses a Z8S180xx CPU. This CPU is basically a Z80 processor with lots of extra peripheral functions built in.
The module provides two 5 volt FTDI style serial ports with software controlled baud rates. The processor’s clocked serial I/O port is available on a header. Also included is a voltage supervisor to give a clean, reliable reset.
The module will typically include an oscillator to provide the CPU with an 18.432 MHz clock. Overclocking, using the Z180’s software controlled clock multiplier, may be possible at 36 MHz.
The recommended firmware is detailed here.
Using the recommended firmware, there are two ways to use SC111, Z180 CPU Module:
- As a native Z180 module. The on-board serial ports, timer and memory management unit are used, but some software and hardware compatibility is sacrificed.
- As a replacement for a Z80 module. This gives good software and hardware compatibility, but does not make use of the Z180’s on-board peripherals, such as the serial ports.
Native Z180 Mode
This configuration requires a memory module designed for the Z180 CPU. This is a simple ‘linear’ memory map with 512k bytes of ROM (usually Flash) at the bottom of the physical memory space, and 512k bytes of RAM at the top. The following modules should be suitable, but only SC119 has been tested.
Note, the official RC2014 “512k ROM 512k RAM RomWBW module” is not suitable. This module includes its own memory management, so is not compatible with the simple ‘linear’ memory assumed for this configuration.
In order to support the extra address lines needed for 1M byte of memory, a suitable backplane is required. Currently, none of the official RC2014 backplanes carry the extra signals. However, the following backplanes do carry them.
- SC112, 6-slot modular backplane
- SC113, 6-slot modular backplane
- SC116, 3-slot backplane
- Others are also available. Look for backplanes with full 80-pin connectors.
Z80 Replacement Mode
In many cases SC111 is a drop in replacement for a simple Z80 module. However, it may require a 7.3728 MHz oscillator to maintain compatibility with existing software and hardware.
Existing CP/M configurations can be used, providing the memory board(s) support paging out ROM, by a write to I/O address 0x38, and allow a full 64k bytes of RAM to be enabled.
The official RC2014 “512k ROM 512k RAM RomWBW module” can be used with the Z180 module. Not tested!
The Small Computer Monitor and existing CP/M builds can be used with most common RC2014 compatibile serial modules. However, this configuration does not support the Z180’s on-board serial ports.
Small Computer Central 