Archive for August, 2006

Intellivision in a joystick – first impressions

Tuesday, August 29th, 2006

The town where I spent my high school years (1981-1986) was small and somewhat remote. There were no stores selling computers or video games in town. The nearest electronics store, such as Tandy (aka RadioShack) or Dick Smith Electronics, was a couple of hours drive away. As such, my friends and I had limited access to these cool toys. In fact, I can count on the fingers of both hands the number of people I knew who had either a computer or video game – I had a Vic 20; my brother’s ids had an Atari 2600; my best friend had a Commodore 64; a family friend had a Vic 20, Commodore 64, Philips VideoPac and one other game system I cant recall; the town doctor had a Dick Smith VZ-200 and later a Macintosh; another family friend had an Atari 800XL; another had a Coleco Adam; and there were a further couple of systems I had a chance to play with. So in some respects, I was lucky enough to be able to experience a number of different systems, but compared to some people who grew up in the same era, my access was somewhat limited. For example, I never got to use the Sinclair Spectrum, the BBC, Oric, Tandy TRS80 or the CoCo, nor did I get to play with the Arcadia 2001, Fairchild Channel F, Bally Astrocade, Nintendo NES, Interton VC 4000, or the Intellivision.

In recent years, thanks to eBay I have been able to acquire some of these systems which were so influential on home computer and video game development. Many of the early game systems in particular can be found very cheaply – in fact I have a HUGE collection of Hanimex/Radofin/Acetronic systems and their variants (aka 1292 Advanced Programmable Video System) which sell for as little as $5. Some systems however attract premium prices, among them the Dick Smith Wizzard (aka Creativision) and the Intellivison. (Although a few Intellivisions have been popping up lately and prices appear to be coming down.)

While emulation remains an option for some, another alternative can be found in the emerging “all-in-one joystick” market. These devices are not much bigger than typical joysticks and plug directly into your television, allowing you to play a number of classic games that you might not otherwise have access to. The variety of these devices is astounding – several based on the Atari 2600, a couple of Commodore 64 collections, a variety of arcade conversions (such as Jakks TV’s Namco series) and a couple of Intellivision models.

A few weeks ago I won an auction for an Intellivision 25 Direct to TV system for $9. Never having played any Intellivision games before, I was interested to see what they were like. I can’t speak for how representative this sampling of games is, so I will leave a review for a later post, but my initial reactions are reservedly positive. Compared to the Atari 2600, the graphics are definitely more detailed yet the gameplay is somewhat lacking. There appears to be a few bugs in the model I have, with some games resetting for no apparent reason and some of the games seem to be unfinished – for example, Motocross only has a single level/course which just doesn’t give the game any real replay value.

Overall, the Intellivision 25 is a neat little pick-up. I may start looking for other all-in-one joystick games to add to my collection even though my first preference is and always will be for the real hardware.

Have you had any experience with an all-in-one joystick? If so, leave a comment and share your stories.

Commodore 64 emulation

Thursday, August 24th, 2006

While I personally prefer to use the real thing, it is smetimes handy to be able to fire up an emulator. I recently posted a link to a web-based ZX81 emulator, now it is the 64’s turn for the web-base emulation treatment. FC64 is an open source, Flash-based Commodore 64 emulator. It still needs a bit of work but looks pretty neat – a Commodore 64 in your browser! ;)

More on the Micro-comp

Tuesday, August 22nd, 2006

I finally found the magazine containing the details of the Micro-comp so I can now give you some more details. The magazine was a one-shot, called Six BD 679 Projects, and the first half contained details of six electronics construction projects based around the BD 679 Darlington power transistor, with the Micro-Comp taking up the remainder of the magazine. (I am at a loss to explain why the Micro-Comp wasn’t featured more prominently on the cover or in the title, but Talking Electronics is a weird mob…) The magazine was published in 1994 and reprinted articles and projects from the Talking Electronics magazine.
Talking Electronics is a local electronics hobbyist company based in Melbourne. Back in the early 1980s (IIRC) TE launched an electronics magazine, which saw some moderate success despite its irregular publishing schedule. In all, fifteen issues of Talking Electronics were published and TE also published a number of one-shot magazines, including six Electronics Notebooks (similar to Forrest M Mims’ notebook series), a two-part Learning Electronics, Digital Electronics Revealed, numerous model railway and FM bug books and a few compilations of popular projects form the Talking electronics magazines. The magazines were generally pretty good and I learned a lot of my electronics chops by studying and building the projects presented therein. On to the Micro-Comp

When I picked up the BD 679 magazine it caught my eye not because of the cover (a nasty two-tone brown affair) but rather the “free” BD679 taped to the front. I was always the sucker for freebies. ;) Flicking through the magazine, the one project that really stood out for me was the Micro-Comp. Ever since I had read about CPU design, I had wanted to try my hand at designing my own computer – the Micro-Comp seemed like a good place to start learning what would be required.

The Micro-Comp uses just three chips – a Z80 CPU, a 2732 EPROM and a 74LS273 as an output buffer. You can’t get much simpler than that! Input is provided by an 8-way DIP switch and two momentary on push buttons. In my earlier post I thought the DIP switches were to select the start address, but that was wrong. The DIP switches are tied to the data bus – the code in the EPROM must read the value of the data bus and use that to jump to the correct start routine on power up.

The clock speed is adjustable, using a trim-pot to adjust an RC network, and the speed can vary from 7.5kHz to 35kHz. As this is really only a “trainer” and not a serious, full-blown computer, adjusting the clock speed can be extremely useful in tracing signals and trying to understand what is happening throughout the system. It is possible to listen to the various bus lines using the audio probe (the fly-lead in the photo I posted in the previous entry) and tweaking the clock speed affects the frequency of the sound.

The programs included in the EPROM are:

  • Jump routine – the “boot loader” which jumps to the memory location specified on the DIP switches at boot up.
  • Tone – outputs a single tone on the high data line
  • Quick Draw – a two-player reaction time game. The first person to press their button when the 7-segment display lights up wins.
  • Running Names – a simple text scroller which displays a message on the 7-segment displays.
  • Looking at Data – Enter a page number on the DIP switches and the values of data in that page are displayed on the 7-segment display in hex with a small delay.
  • Counter – Increments a counter with each press of button ‘A’ and displays the output on the 7-segment displays.
  • Auto-increment/Auto-decrement – variable counters.
  • 4×4 Display – Displays a series of patterns on the 4×4 LED matrix.
  • Dice – Displays a random die roll on the 4×4 matrix.
  • Slot Machine – “Rolls” random patterns down the 4×4 LED matrix in a very simple slot machine simulation. 4 lit LEDs in a row wins!
  • Binary Clock – Uses the 8 LEDs as a binary clock/counter.

Most of those probably sound quite dull and uninteresting, but if you’ve built the computer and study the code for each of these simple programs, you can learn quite a bit about the workings of a real computer. Studying memory locations, data busses, loops and timers, multiplexing displays and so forth are the real aims of this project and I have to say I did learn a heck of a lot by building this and playing with it. Unfortunately I never had an EPROM burner, so I couldn’t write my own programs to test – maybe that is something I should address when I get some spare time…

A number of extra programs and add-ons were made available through the magazine. Two that I know of that were published in the magazine were a Blackjack program and an add-on board to play noughts and crosses. IIRC, a RAM pack, non-volatile RAM, morse-code trainer and relay driver boards were also available.

The things you learn on teh intarwebs!

Monday, August 14th, 2006

I thought I knew a fair bit about Commodore computers, but so much of what I knew turns out to be wrong. At least, it’s wrong according to this guy.

I didn’t realise how little I knew… ;)

Organising…

Thursday, August 10th, 2006

I really need to organise my colllection of old skool computers and video games. In fact, part of the reason for this site was my desire to create on online system for organising such a collection – that’s why I registered the domain name OldSkoolComputing.com.

So what do I need this syetm to do?

  • List the computers and video games in my collection
  • Brand
  • Model
  • Serial Number
  • Manufacturer
  • Configuration
  • Condition
  • General notes
  • Provide details about the manufacturers of these systems
    • Name
    • History
    • Computers and video games produced
    • Notable people
  • Track documentation (manuals, magazines, etc)
    • Title
    • Author(s)
    • Publisher
    • Relevant systems
    • Notes
  • Track peripherals
    • Make/model
    • Compatible systems
    • Manufacturer
    • Condition
    • General notes
  • Track software
    • Title
    • Publisher
    • Platform
    • Media
    • Condition
    • Notes

    Each item could have an information page (or pages) containing technical details, history, pictures, and any other relevant information that fits. Items should be able to be marked as “for sale” and the ability to create “want lists” would be handy. Plus I’d like to make this a multi-user system, so anyone can track their collections with the ability to search for other users and trade with them.

    So does anyone have any thoughts on this idea?

    Emulation

    Tuesday, August 8th, 2006

    If you never had a chance to play around with some of the real old skool hardware back in the day, and can’t afford to buy some old hardware off eBay (Sinclair ZX80s can fetch over $300USD for example) then emulation is probably your best shot. Personally, I love the feel of a real machine under my fingers – nothing beats responsiveness of a Sinclair keyboard! (Well… actually… everything beats the feel of a Sinclair membrane keyboard… But there is something to be said for hammering away on the real deal.)
    A few days back I found a Sinclair ZX81 emulator online. This emulator is neat – it is written in Java and lives completely within a web page. You can even load and save your programs. There’s a reasonably good programming reference, just in case your Sinclair skillz are rusty and a nice collection of programs ready to try out. About the only things you’ll miss out on are trying to get the levels right on your cassette player so you can load the software, and the fun that comes with trying to tune your TV to the Sinclair signal… ;^)

    Moved…

    Sunday, August 6th, 2006

    I have moved this blog over onto its own domain – OldSkoolBlog.com. Please update any bookmarks and links. Old links to OldSkoolComputing.com/blog should still work, I hope. (Update: I’ve managed to get the redirection happening properly now.)

    If you find anything that appears to be broken, please let me know by commenting here, or arb {at} OldSkoolComputing {dot} com.