Nascom 1

The Nascom 1 was the first in a series of two single-board computer kits released between 1977 and 1979 by Nasco in the UK. They were both based on the Zilog Z80 microprocessor and included a keyboard and video interface, a serial port and two 8-bit parallel ports. The system was unique for the time, since it included a full “real” keyboard and a video interface was uncommon. The hobbyist had to hand-solder about 3,000 joints on the board.

Personal Computer World cover May 1978

Personal Computer World cover May 1978

The “nerd public”, or those that were reading computer magazines in the late 1970’s were first introduced to the Nascom 1 in the May 1978 issue of a UK magazine called “Personal Computer World” in May 1978

One thing quite interesting with the Nascom is the conventions used to operate them. For those who don’t have much knowledge of computing in the late 1970’s, it certainly was different than even what many people remember from in early 1980’s computers, when you turned on your computer and had BASIC ready to go. The Nascom operated with a rudimentary command set comprised of single letters. This command set was called “Nasbug.” You typed a single letter, followed by a HEX memory location if needed, then pressed the Enter key. For example, to set a breakpoint in program execution, you would type:

Bxxxx <Enter>

where xxxx is the hexadecimal address where you want to set the breakpoint. To execute a program, you use the command:

Exxxx <enter>

Most programs ran from location $0000. If you wanted to load a program from an external serial device, probably a punch card reader or paper tape, you would just type:

L <Enter>

Future versions of the Nascom, like the Nascom 2, would have an enhanced command set, called Nas-Sys,, having commands like “S” for Save because the hardware supported saving your programs directly.

Nasbug v1.T2 Command Set

Command Purpose Operand Example
B Set Breakpoint at XXXX address
  • HEX Memory Address
C Copy ZZZZ of memory from XXXX to YYYY
  • From HEX address
  • To HEX address
  • Hex length to copy
D Dump memory from XXXX to YYYY to serial interface
  • Start HEX address
  • End HEX address
L Load from serial device
  • (none)
M Modify data starting at XXXX
  • Start HEX address
  • A series of two-character HEX values representing data, followed by a typewritten “.” to end the command
S Single step through program execution starting at memory location XXXX
  • Start HEX address
T Tabulate (list) the contents of memory starting at XXXX and ending at YYYY
  • Start HEX address
  • End HEX address
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Here is a video of a Nascom 1 in operation

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