Dick Smith Super-80 Computer

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Super-80
RAM, 2kB (maximum 12kB) ROM
StorageCassette Tape (300 Baud, Kansas City Standard)
DisplayMonochrome, 32 × 16 Characters, Upper Case Only

The Dick Smith Super-80 was a

Dick Smith Electronics
.

It was presented as a series of construction articles in Electronics Australia magazine's August, September and October 1981 issues.

Electronics Australia had published a number of computer projects before the Super-80, including the

EDUC-8
in 1974, the Mini Scamp and the DREAM 6800 Video Computer.

The computer was sold as a "short form" kit for

RAM and a 2kB EPROM containing a machine code monitor program. The technical manual and power transformer were sold separately, as were a kit of I.C. sockets, a BASIC
interpreter program and from mid-1982 onwards, a metal case to house the computer.

The computer proved to be a popular construction project, with an advertisement in November 1982 claiming: "Over 2000 sold."[1]

The popularity of the Super-80 led to a small industry growing up around addressing the shortcomings of the original computer - especially the black and white, 32 × 16 character, upper case only video display.

The original name of the computer was "Nova-80", but it was changed at the last minute to avoid "possible legal ramifications".[2]

Specifications

  • CPU: Zilog Z80
  • Clock Speed: 2 MHz
  • Expansion: S-100 Bus Slot (Optional)
  • Keyboard: 60 Key
  • Mass Storage: Cassette Tape (300 Baud, Kansas City Standard)
  • RAM
    : 16kB (maximum 48kB)
  • ROM: 2kB (maximum 12kB)
  • Sound: None
  • Video Display: Monochrome, 32 × 16 Characters, Upper Case Only

Technical description

Super-80 computer logic board (reverse side)

The Super-80 was based on the Zilog Z80 8-bit microprocessor. As standard, it had 16 kB of dynamic RAM in the form of eight 4116 RAM chips. RAM could be expanded to 32 kB or 48 kB through the addition of rows of eight 4116 RAM chips.

The computer was assembled on a single double-sided printed circuit board. The board was supplied in a light cardboard sleeve that appeared to be an LP record sleeve, having the words "Dick Smith Super 80 Microcomputer Kit Printed Circuit Board" and the part number "Cat H-8402" printed along the spine.

To keep the price of the computer and the component count down, a novel technique was used to implement the video display. Instead of an expensive video display controller chip with dedicated memory, the Super-80 used discrete

I/O
port.

The keyboard was part of the main computer PCB, but before assembly, the constructor could opt to cut the keyboard section of the printed circuit board off and connect it to the main board with ribbon cable. The keyboard was wired as an 8 × 8 matrix and connected to the computer via the two 8-bit ports of a Z80 PIO chip. Pressing the keys <CTRL>, <C> and <4> at the same time generated an interrupt that would perform a "warm start" of the monitor program. The keyboard 'read' routine supplied in ROM was "negative edge triggered" and would block while a key was down. As a result, most action games incorporated their own keyboard driver.

The standard computer had no serial or parallel I/O as such, relying on the optional S-100 bus interface for I/O and expansion. A 10-pin connector at the back of the board was labeled "PORT" and had power, as well as a pair of digital outputs and two available digital input lines. The connector was for a future RS-232 / 20 mA current loop serial interface,[3] but that was never implemented.

Mass storage was available in the form of a cassette tape interface running at 300 baud. Accessing the cassette interface required the video display to be switched off, so an

LED
was provided to show activity during a tape load or save operation. The LED would change state each time a 256-byte block of data was successfully transferred.

The Z80

interrupt line was connected to the keyboard PIO and the "Non Maskable Interrupt
" line was not connected.

Software

The Super-80 came with a 2kB machine code monitor program in ROM.

A

Tiny BASIC rewritten and modified by Ron Harris.[4]

In its November 1981 edition (p93), Electronics Australia announced a programming competition with the chance to win one of two

dot matrix printers. The magazine later compiled the better programs submitted by readers into a book called Software for the Super-80 Computer.[5]

Accessories and options

Super character generator board for the Super-80 computer
  • B-3600 Super-80 Technical Manual
  • B-3602 Super-80 BASIC Handbook
  • H-3200 Metal Case
  • K-3602 BASIC Interpreter on Cassette Tape
  • K-3603 I.C. Socket Kit
  • K-3604 BASIC Interpreter in EPROM
  • K-3606 S-100 Expansion Unit
  • K-3607 Lower Case Character Generator

Modifications

Many Super-80 owners chose to modify their machines to address the limitations of the original machine.

The El Graphix kit added the ability to display lower case characters and "chunky" graphics.

The Printer Interface was an S-100 Bus card giving the Super-80 a Centronics parallel printer port.[6]

The VDU Expansion Board (VDUEB) was an enhanced video display board for the Super-80 developed by Microcomputer Engineering (MCE). The VDUEB gave the Super-80 an 80×25 video display with limited graphics capabilities. It was based on a

Microbee games being ported to the VDUEB equipped Super-80. The VDUEB proved to be a popular modification, with a users' group
forming for owners of VDUEB equipped computers - The "Super-80 VDUEB Users' Club".

The Universal Floppy Disk Controller (UFDC) was an add-on

double density using a Mitsubishi floppy drive mechanism. This gave a formatted disk capacity of 800kB. The UFDC's use of DMA required the VDUEB upgrade to be present. To install the disk controller, the Z80 CPU was removed from the main computer board and installed on the UFDC board. The UFDC then piggybacked on the socket vacated by the CPU. This meant that in theory, the UFDC could be used with almost any Z80 based system, provided there was enough physical space above the CPU. The UFDC used a primitive track based disk operating system called "Super-80 DOS", however a CP/M BIOS
later became available.

The MXB-1 Memory Expansion Board was designed by a member of the VDUEB Users' Club. The MXB-1 contained space for extra EPROMs, an optional battery backed

RAM disk
.

The El Graphix "X-RAM" board provided up to 16K of battery backed CMOS RAM or EPROM. Several X-RAM boards could be piggybacked allowing each to be port selected as independent 16K banks of memory. This memory took the form of 8 x 2K 24pin sockets which accepted either 2016 CMOS RAM or 2716 EPROMS. As the system ROM shared part of the address range taken up by the X-RAM board the system ROM could be copied into CMOS RAM on the fly and modified as required to actively add or modify custom functions into the operating system.

See also

References

  1. ^ a b Dick Smith advertisement. (November 1982). Electronics Australia, p. 101.
  2. ^ "Super-80 Computer". (August 1981). Electronics Australia, p. 70.
  3. OCLC 220572735
  4. ^ (1981). Dick Smith Super-80 Basic Reference Manual. p. 2. Dick Smith Electronics.
  5. ISBN 0-909558-14-0
  6. ^ "A printer interface for the Super-80". (May 1982). Electronics Australia, p. 80.

External links

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