RC2014 a simple ROM/RAM card

July 12, 2020

It’s been a while since we published any thing new for the RC2014 architecture.

This is a simple combined ROM and RAM card designed to work with the RC2014 bus. This is an experimenters board. There is no fancy memory paging etc., it’s simple memory architecture was designed to be flexible and allow the user to experiment with other CPU architectures on the RC2014 bus. It was originally designed to work with our 8052 CPU.

It features

  • enhanced RC2014 bus
  • Selectable memory* options 8K, 16K or 32K
  • Board can be used as RAM only or ROM only or both.
  • Options for nMRD/nMWR or nRD/nWR signals
  • Option for 27C512 with Hi/Lo ROM (A15) select
  • IC Decoder 74xx138 using A15/A14/A13 (with extra options for A13 & A14)
    8 or 16-bit wide data bus**
  • moveable memory positions (i.e. ROM can be at top or bottom memory space)

A couple of important notes:
* Both ROM and RAM memories must be the same size.
** see explanation below

The option for either nMRD and nMWR (nRD and nWR or’ed with nMREQ) signals or nRD and nWR only signals when IC3 (74xx32) is fitted or not fitted allows for experimenting with other CPU Read/Write architectures.

Notably, the enhanced RC2014 bus features a 16-bit data bus. The card can use this enhancement by allowing the selection of the high or low 8-bit portion of 16-bit data bus. This allows the user to experiment with 16-bit CPU’s such as 68000 or 8086 when two cards are used together.

It’s schematic is here

RC14_MEM_RAM_ROM_PCB1RC14_MEM_8052_RAM_Module_smRC14_MEM_RAM_ROM_Module_sm

 


P2 ES evaluation system prototype wings

February 26, 2020

Last year Parallax released their latest multicore processor, the Propeller2 or P2X8C4M64P to give it, its full name. It’s been a very long time coming and after a few setbacks it is finally here. It’s specs are very good, featuring 8x 32-bit cores (or cogs as Parallax likes to call them), 512K RAM and 64 GPIO with SmartPin features.

I got my P2 evaluation system (ES) board a few weeks back and designed a couple of P2 ES prototyping wings to go with it.

The first prototyping wing (on the right) is a classic proto board with I/O from two GPIO ports. The other prototyping wing is a breadboard design for faster circuit build and test and features a 3x LED’s and 2x switches

I’ve got a few spare PCB’s which I’ll put on my Tindie store.


RC2014 Z80 System with enhanced bus

January 28, 2018

I’ve been busy with my big box of PCBs and I here’s my first Z80 system design and build. It comprises of the following:

– Z80 CPU card
– 8K ROM & 8K SRAM card
– 68B50 ACIA card
– 5-slot enhanced+ backplane

It’s pretty much a standard Z80 layout but I’ve expanded the bus to the latest Enhanced Bus definition for all the cards. The 5-slot backplane uses double row (2×39) female pin headers to include the RC2014 enhanced bus and in addition I’ve added an extra set of address lines (A16 to A23) for the possibility of using 16-bit CPU’s (8086/68000) and memory options (upto 1MB) in the future.

Here’s some pics of the various cards:


Z80 Card

Memory Card

 

ACIA UART Card

 


Retro Computing with the RC2014 Bus

November 29, 2017

I have very fond memories of using and building 8-bit computers during the 1980’s, so I’ve been following Spencer Owen’s RC2014 modular 8-bit computer project with some interest. For those interest the RC2104 is a simple but very modular 8-bit microcomputer based around the Z80 microprocessor.

In its most basic form it uses a number of single row 40-pin headers (or sometimes a 39-pin header) to make a computer backplane and which takes various “computer” and add-on cards to build a system. The add-on cards currently have a choice from various Z80 CPU cards, a 6502 CPU, various sizes of RAM and ROM memory cards, serial I/O and digital I/O cards.

I was fortunate to meet Spencer at Maker Faire UK back in April 2017 and chat with him first hand about the RC2014 project and he was very open and enthusiastic about sharing all aspects of his project. So much so, a small community of fellow builders has popped up and added to the project with their own add-on cards.

 

I’ve put together a short list of RX2014 related web-sites:

https://rc2014.co.uk/
https://github.com/semachthemonkey/RC2014
https://github.com/RC2014Z80
http://www.sowen.com/tag/retro-challenge/
https://github.com/RFC2795

http://www.smbaker.com/
https://github.com/sbelectronics/rc2014

http://ancientcomputing.blogspot.co.uk/
https://github.com/ancientcomputing/rc2014

https://github.com/electrified/rc2014-ym2149

https://github.com/mattybigback/RC2014

https://github.com/anachrocomputer/RC2014tester
https://github.com/mooped/rc2014_bank_switcher
https://github.com/mooped/rc2014_tools
https://github.com/trcwm/rocket2014

Other Platforms
http://www.ndr-nkc.de/compo/index.htm //very similar system from 1980’s
http://hschuetz.selfhost.eu/ndr/doku/buch/index.html
https://www.retrobrewcomputers.org/forum/index.php?t=msg&goto=2148&
https://www.funkenzupfer.de/CMSimple_4-7-2/?NDR-Klein-Computer


ESP32 links

July 29, 2016

The WIFI enabled ESP8266 is one of those great chips to quote an old tradesman’s saying “it just does what it says on the tin”.

It’s only been around for a few short years but it’s made a great impact in the boom in WIFI enabled projects and products.

Building on this success of the ESP8266, Espressif announced the ESP32 late last year (2015).

As well as WIFI the ESP32 also features:

  • Dual Core 32-bit Micros
  • RAM 512KB
  • ROM 128KB
  • WIFI
  • Bluetooth
  • Ethernet
  • UART x2
  • SPI x4
  • I2C x2
  • I2S x2
  • SD/SDIO
  • CAN
  • GPIO x36
  • ADC 12-bit x16
  • DAC 10-bit x2
  • PWM
    and more

With the ESP32 August release date fast approaching you can now find more solid information on its capabilities. Here’s a few links to wet your appetite:

Getting Started

http://www.espressif.com/en/support/explore/get-started/esp32/sdk-user-guide

ESP32 Dataheet

Click to access ESP32_datasheet_0705.pdf

ESP32 Pinout
http://www.pighixxx.com/test/portfolio-items/new-esp32-espressif-specs/?portfolioID=337


New ESP8266 with Bluetooth and 500K RAM?

August 31, 2015

This is a little late but I spotted this tweet from Espressif and a post on CNX about a new variation of the ESP8266 going into beta testing. The company announced the new chip which will support both Wi-Fi and Bluetooth Low Energy (BLE).

There’s not much more information other than it features a new 32-bit core, the Tensilica diamond 108 instead of the 106 and has 500KB of RAM.


ARDvance-Pi v0.1

December 31, 2011

The ARDvance-Pi is an advance Arduino training board. You can use it together with any of the Ardunio Uno or Duemilanove style of boards. The Arduino is plugged into the ARDvance-Pi and DIL switches allow the user to select which interfaces or circuits they want to connect to the Ardunio.

The training board has a number of interfaces

  • 6 x Rotary Potentiometers
  • 2 x Linear Potentiometers
  • 4-Digit, 7-segment LED display
  • Temperature Sensor
  • Light Sensor
  • Buzzer Output
  • 5V/3.3V switchable PSU
  • Prototyping area
  • 8 x LEDs
  • 8 x tactile switches
  • 1-ch Relay (Change Over)
  • RS232 interface with 9-W D connector
  • H-Bridge Motor Controller (based on L298)
  • XBee socket
  • 16-way keypad*
  • LCD interface*
  • 5V to 3.3V logic conversion for Raspberry-Pi

* Note: if space allows

It was originally going to be called the ARDvance-10 but its name changed when I decided to add an interface port for the Raspberry Pi board, hence its new name ARDvance-Pi. Port Expanders, either MCP23008 or PCF8573 and a 8-ch ADC will also be added to allow I2C or SPI interfaces to be used from the Raspberry-Pi. When its finished, its hoped that the Raspberry-Pi can use the Arduino as a sort of slave I/O processor.

The schematic is here: Ardvance Pi Schematic 0v10


A tale of two boards

May 24, 2011

Lately I’ve been keeping my eye on two recent developments from Xmos and Parallax.

The Xmos staff are developing a Stamp (40-pin DIP package PCB) like board for their XS1-L1-TQFP48.

Mean while Parallax to support their Semiconductor spin off have brought a new Quick Start board of their popular Propeller P8X32A multicore microcontroller.


An Arduino pimped Big Trak

November 28, 2010

I picked up a Big Trak programmable vehicle from a car boot sale a few years ago where it promptly got lost in my to be used in a cool project (aka junk) pile. The recent Dorkbot @ Newcastle project session saw me dig it out of my attic with the goal of swapping out the original controller board an replacing it with an Arduino.

To make this work I needed a motor controller circuit to drive the wheels of the Big Trak. There are a number of Arduino motor controller shields I could have used but I already had a couple of ST L6203 H-Bridge Driver chips left over from a previous project so I put together a quick dual motor controller design using these.

A pdf of the initial schmatic design is here

Big Trak


XArduino – A 400-MIPS co-processor for Arduino

February 7, 2010

Recently I’ve been working on XArduino which is a XMOS XS1 L1 co-processor for the Arduino open-source electronics prototyping platform.

The XArduino board provides Arduino applications with a 400 MIP’s multi-threaded 32-bit co-processor, as well as providing a VGA video output and PS/2 keyboard/mouse input for Arduino application.

It features a standard XTAG-2 to for programming and debugging. In addition the XTAG-2 interface will allow for XK-1 boards to access the VGA and PS/2 interfaces as well as way of connecting standard Arduino shields.

Note: This is a 3.3V-only board

The project is hosted at xcores.com/projects/xarduino

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