Nascom 2

Posted by musovern on Jun 27th, 2019 in Nascom 2 | 0 comments

The Nascom 1 and 2 were single-board computer kits issued in the United Kingdom in 1977 and 1979, respectively, based on the Zilog Z80 and including a keyboard and video interface, a serial port that could be used to store data on a tape cassette using the Kansas City standard, and two 8-bit parallel ports. At that time, including a full keyboard and video display interface was uncommon, as most microcomputer kits were then delivered with only a hexadecimal keypad and seven-segment display. To minimize cost, the buyer had to assemble a Nascom by hand-soldering about 3,000 joints on the single circuit board.

The original Nascom 1 was designed by Chris Shelton. Shelton’s design work was outlined in a series of articles published between November 1977 and January 1979 by Wireless World magazine.

 

 

 

 

I got my unit from our local auction site which didn’t come with any keyboard and is at present not going and was installed in a suit case and has all the connections on the outside of the case. It was in poor condition.

started debugging the video circuit.

The Nascom 2 showing power side it in the suite case

The mighty Z80 CPU

Backed up all the EPROM’s and burned a new Character Generator EPROM.

The video circuit working with just the Character Generator replacement EPROM.

Added the video RAM ic so have random characters displayed –  happy with the progress so far.

Next on to the CPU and memory decoding.

 

I finally got back to the Nascom 2 and programmed a new set of PROMs and NAS-SYS ROM and it’s not showing life

Checking Memory decoding with the Z80 ICE emulator

NAS-SYS 3 on the screen

Keyboard tested and working. Now to get Microsoft BASIC working.

 

Ya it works. It’s now time to make a new case for the computer.

Started with some scrap pine for the sides and folded up some 1.8mm Aluminum.

Top side cut out for the keyboard

The test fit with transformer and the Backplane

 

Demo of the Cassette interface using my ipod.