512k ROM 512k RAM Module

The 512k ROM 512k RAM Module allows the RC2014 to run RomWBW, a CP/M-like operating system that takes advantage of the extra memory by paging in and out chunks of 32k as required.

The Hardware

This module is a combined 512k RAM and 512k ROM module that has been designed to run RomWBW operating system on the RC2014 with a Z80 CPU. Due to the 64k of addressable memory limitation of the Z80, the memory in this module is divided up in to multiple 32k pages.

It is designed to replace both the ROM and RAM modules in the RC2014 ClassicRC2014 Plus or RC2014 Pro, and can also be used with the RC2014 Mini if the ROM and RAM chips are removed.

The circuit is largely a reproduction of the ROM/RAM part of Sergey Kiselevs Zeta 2, with some modifications inspired by Dr Scott Bakers ROM/RAM Module

The Software

RomWBW is a ROM-based implementation of CP/M-80 2.2 and Z-System for all RetroBrew Computers Z80/Z180 hardware platforms including SBC 1/2, Zeta 1/2, N8, Mark IV, and RC2014. Virtually all RetroBrew hardware is supported including floppy, hard disk (IDE, CF Card, SD Card), Video, and keyboard. VT-100 terminal emulation is built-in.

The RomWBW ROM loads and runs the built-in operating systems directly from the ROM and includes a selection of standard/useful applications accessed via a ROM disk drive. A RAM disk drive is also provided to allow temporary file storage.

As the author of RomWBW, Wayne Warthen has ported this operating system to the RC2014, and it will auto detect either the 68B50 ACIA or the SIO/2 UART, and will, if available, use the Compact Flash Module for storage. It can also support Ed Brindleys IDE Module and RTC Module, as well as Dr Scott Bakers WDC and FDC Floppy Disk Moduleswith a recompiled base image.

For detailed information on RomWBW see https://github.com/wwarthen/RomWBW

Buy one here

Bill of Materials

1 RC2014 512K ROM RAM PCB
1 ASC6C4008
1 ST39SF040
1 74HCT74
1 74HCT138
1 74HCT139
2 74HCT670
4 1k resistor
4 4k7 resistor
6 100nf
1 40 pin RA header
1 14 pin narrow DIL socket
4 16 pin narrow DIL socket
2 32 pin wide DIL socket