Introduction

Why “jmp start ;microcomputers”? Well, ultimately it’s just a name. It sounds like “jump start”, but it’s also a pretty common line of assembly language. It’s a bit technical, but so is this site. I tried some AI names, but this came out of my head.

A microcomputer is a computer that is based on a microprocessor; a highly integrated processing unit that first appeared in the early 1970s. The term “microcomputer” was used a lot during this early adoption period but fell out of fashion by the early 1990s. Microcomputers are now referred to as PCs, notebooks, tablets, phones etc, so i use the term “microcomputer” as a shorthand for “vintage microcomputers” which are the subject of this site.

As i emerged from high school in the early eighties, microcomputers were the tech that everyone wanted, and this prompted me to enter the world of electronics. I got to play with several early machines, but there were so many that it was impossible to experience the gamut.

Over the last 8 years, i’ve had the opportunity to not just reacquaint myself with some familiar machines, including a couple i sequestered from those times, but also to experience many that i missed the first time around.

I’ve purchased many of my treasures through well known online marketplaces, but i have also acquired many from colleagues at the Adelaide Retro Computing Group – always at reasonable cost and often as generous gifts. I’ve tried to acknowledge significant gifts as i’ve added detail, but i apologise in advance if i have missed anyone.

I’m typically interested in workhorse machines but use the occasional game to demonstrate what a computer can do, or in many cases its limitations.

Making machines shine figuratively is my goal, including:

  • Getting them working
  • Getting them working again after they stop
  • Adding software
  • Adding accessories
  • Connecting them

My machines are not pristine or mint – i aim for tidy and functional. I like them to be exercised regularly and standing by, ready to save mankind when the current tech collapses in upon itself like an abused CRT.

Generally i will try to make sure that machines are either original or can be readily taken back to original – and that includes modifications from, or typical of, the operating period.

I do compromise on hard disks; they are difficult to source and inherently unreliable. I never bin them, but i don’t think twice about replacing them with hard disk emulators. I also use disk emulators alongside original storage peripherals to make it easier to try, and to demonstrate, a greater range of software.

The purpose of this site is to:

  • Show off some of my machines
  • Make what i’ve learnt available to others
  • Promote related local activities and groups

The info that i’m posting has been extracted from the notes that i have accumulated since 2017. Those notes were pretty rough and not always complete. Mostly i’ve rewritten them here, but their heritage still comes through in places.

My hobby relies on the amazing work that has been done by so many people to archive data – programs, disk images, data sheets, schematics, manuals, articles, photos, problems and solutions. I use these resources extensively, and i am grateful for them. I try to pay this forward by archiving disks and documentation to archive.org or other appropriate sites such as Microbee Technology.

Adelaide Retro Computing (ARC) Group

I started attending ARC Group meetups in about 2018 and have been a regular since then. This group has been a game changer for my hobby.

Some might describe retro computer collectors/operators/builders/gamers/hoarders as a little unusual, and numerous stereotypes are routinely rolled out. Many of us wear them as badges of honour.

Retro is a vague but inclusive term, and the group members and meet attendees reflect that diversity. This group is an opportunity for those people to meet in a friendly atmosphere to play games, show off builds, acquisitions, and restorations, and to talk bullshit about computers and life in general.

As a group, we have a lot of knowledge and skills that are of value to each other. There are many people with eyes on marketplaces, auctions, recycle bins, garage sales etc, so often group members are able to direct gear to the people with matching interests. The group is often a focus for downsizers etc, who are looking to clear cupboards and sheds.

If you’re in Adelaide and you have an interest in the retro computing world and adjacent interests, then come and have a look. The group meetups are the second Friday of each month. Check the facebook page for details.

Tandy TRS-80 Model I

Generously given to me by Michael from the ARC Group.

The Model I was originally released in 1977, but this one was made in about 1980. It has 16k of memory and has been highly modified.

It also came with an expansion unit with RS232 interface and 32k of additional memory.  There was no disk drive, but that was only a minor obstacle.

It also came with an original monitor (probably not the ideal one to use with the expansion box), buffered cable to connect the computer to the expansion unit, a box which turned out to be a high resolution graphics mod, a joystick, and dust covers.

Spare Parts

I have accumulated a quite a lot of pre-1990 spare microcomputer parts including a lot of LS TTL, transistors, diodes, LSI parts in the Z80, 8085, and 8088 ecosystems, seven segment displays, and various analog ICs.

I have no inclination to mail these out, but i can help hobbyists in the Adelaide area, particularly members of the Adelaide Retro Computing Group.

I’m probably not going to be able to help out with bulk RAM or recap projects. You’re on your own!

BSides Adelaide May 2025

A couple of my colleagues, Mike and Craig, and i represented the Adelaide Retro Computing Group at the BSides event in May 2025.

They gave us half of a very large room at the Adelaide Hilton. Between us, we had about 15 retro/vintage machines for the cybersecurity community to experience.

The scene below is how things looked just prior to the start of the second day.