Old Skool Blog

Bil Herd, one of the key designers of the Commodore 128, popped into the Retrobits forum to explain how and why the Z80 made it into the Commodore 128. So if you ever wondered why the 128 had a CP/M mode, here’s the story straight from the horses mouth.

Damn! I just discovered that Jim Butterfield, one of the leading lights of the Commodore world passed away on June 29, 2007 after losing his battle with cancer. I remember reading countless magazine articles and one or two books written by Jim over the years – he was one of the more prominent computer authors in the 80’s and he will be sorely missed. 8^(

Time to dig out some old magazines and re-read some of his material…

Here’s a list of various kits and projects based on classic microcomputers of yesteryear. Some of these are true to the original (down to using original components where possible) while others are re-imaginings of old systems.

• Micro-KIM – A KIM-1 clone that appears to be reasonably true to the original, though with a few modifications and an added serial port
• Replica 1 – A replica of the original Apple, with a couple of “modern” enhancements (such as the option of a USB port)
• COSMAC Elf 2000 – A reproduction of the COSMAC Elf with some modern enhancements
• Roll your own PET 4032 – A PET 4032 clone based on the CS/A65 project
• Kenbak-1 Series 2 – A faithful reproduction of the original Kenbak-1
• Altair 8800 – A faithful reproduction of the original Altair 8800
• IMSAI Series 2 – Based on the computer that appears in War Games
• Sinclair ZX81 – Original Sinclair ZX81 kits – not a clone or a replica, but the real deal!
• Sinclair ZX80 clone – If you want to try building a ZX80 completely from scratch
• Jupiter Ace clone – Similar to the ZX80 clone above

I have a couple of the Sinclair ZX81 kits and will be ordering the Micro-KIM and Replica-1 kits shortly. As for the others, well I’d love to have them all, but can realistically see myself getting the COSMAC Elf and maybe a Kenbak. I’d love the Altair, but just can’t see myself being able to afford the cost.

I think it is time to (temporarily) halt my eBay activities. At least until I get my current collection properly sorted out and catalogued. I’m spending way too much time buying “new” computers/peripherals/software/books when I don’t really know exactly what I have and can barely find the time to play with use what I have.

So the action plan is:

1. Find a suitable shelving solution
2. Sort my current collection
3. Catalogue the collection electronically
4. ???
5. Profit?

I really should start checking rarity lists before bidding on items on eBay. Recently a couple of old consoles were listed on eBay as an auction with a “buy it now” price. I didn’t think the consoles would attract too many bids (they weren’t particularly rare) but the BIN price was a worry – it was (IMHO) too much for the pair, but not so high that someone wouldn’t snatch the items before the auction ended. Normally I don’t bid too early in auctions, instead preferring to watch and wait so I can snipe at the last minute, but in this case I decided to put in a minimal place-holder bid to remove the BIN option. Bad move!

When I checked the auction in the dying hours, I saw that the bids had skyrocketed to more than twice the initial BIN price. At first I thought it was a case of newbies experiencing a sudden rush of blood to the head, but had a closer look at the photos attached to the auction. One of the included cartridges looked a bit different to normal, so I did what I should have done on day one – I Googled for a rarity guide and checked up on the cartridge. It turns out the cartridge in question is an extremely rare item which I could have snatched for a steal if only I had done my research up front.

Moral of the story: Do your research before bidding on auctions and look closely at any photos to determine just what is on offer.

(I haven’t had any time recently to update this blog – we are heading into our busy period at work and I’ve barely had time to scratch myself…)

In the past couple of weeks I have made a few additions to the collection, courtesy of eBay. eBay has made collecting old systems remarkably easy, making it a snap to locate systems that I had only ever read about in imported magazines. Unfortunately eBay has also had a negative impact on this hobby, but that is a topic for another post.

The latest goodies that I have added to my collection include:

• An Oric-1 (though it has a dodgy power supply which I can easily replace)
• Some Mattel Aquarius cartridges – a couple of games and an implementation of LOGO which I am dying to try out!
• Another Intellivision console, complete with the Intellivoice module, Intellivision Computer Adapter and a bunch of games.
• A Dick Smith Wizzard (aka vTech Creativision – this is a very hard to find games console, so I am stoked to have won this auction
• A second Mattel Aquarius system, complete in its original box, with the expansion system and game controllers.
• and best of all, a working Vectrex system!

The Aquarius and Vectrex systems haven’t arrived here yet and I can’t wait to get my hands on them. The Aquarius turns out to be a really neat, if limited, system. There is something about the system that is intriguing – it is very under-powered, was over-priced when it came out, had a limited life, but it looks good and I find myself drawn to the system. Given the limited life of the Aquarius I am surprised at the number of unopened software which is readily available. Perhaps this shouldn’t be such a surprise though – the
Aquarius was killed very early on, so maybe stores and distributors were left with large stocks of unsaleable merchandise? Hmmm… Either way, it means there is a decent supply of collectible items for this system, which is a good thing IMHO.

The Vectrex has really got me excited though. I remember a friend of mine had a Vectrex in the early 1980s and it was a cool game system – the vector graphics, with an integrated monitor crapped all over my little Pong clone I had. The high price and poor reliability of the systems led to an early demise, which means that working Vectrex units are quite hard to come by and they attract a premium price. Still, I got this one for much less than I expected, so I am happy. Now I will have to start hunting for the games – it looks like there were 29 games released, which is more than I thought, and there are almost as many home-brew titles too.

The past week or two I have been fighting what seems to be a losing battle. My TV (32″ LCD) just doesn’t want to work with either of my ZX80s. It does work fine with my Commodores, the Aquarius, most of my ZX81s and various game machines – just the ZX80s seem to give it grief. When I try to tune in the channel, “auto-tune” skips right past the channel without even a blip, and “manual tune” will sometimes show a very fuzzy picture but won’t let me stop close enough to fine tune it.

The few, tantalising glimpses I get when using manual tune are enough to convince me that a) the ZX80s work (at least intermittently); and b) theoretically it should be possible to tune a correct channel in.

I have tried bypassing the modulator and just taking a composite signal straight from the circuit board, but even that isn’t getting much success. I can sometimes get a brief flash of the ZX80 screen up, but it just doesn’t seem stable enough.

My next step will be to dig out my old TV from the back room, which has a manual tuning mode which is much easier to control than the modern tuning mechanism on my LCD TV.

Of course my ultimate solution is going to be to use a TV tuner card which would allow me to take screen grabs (and even create movies) of the old skool machines in action. Unfortunately I don’t currently have a spare slot in my Windows PC and USB tuners for Macs are just ridiculously over-priced, so it may take a while before I can use this option…

Sigh! It never used to be so hard to tune in a channel on your TV. Whatever happened to the rotary tuning dials?

I found a site which has a disassembly of the Aquarius ROM, as well as some other technical info and an emulator. Looks like I have a bit of reading to do!

As I mentioned in the previous post, Mattel disabled PEEKing into the ROM. The author of this disassembly wrote a small machine language routine which copied chunks of the ROM into RAM so he could dump the ROM contents. This was what I was planning on doing, but now I won’t have to.

At least now I have a list of BASIC keywords. Appears to be a reasonably standard set of commands for an 80’s home computer…

I’ve been playing with my “new” Mattel Aquarius, trying to find out what it can and can’t do. The BASIC appears to be standard fare for early-80’s Microsoft BASIC, if a little limited. The character set is interesting, containing crude graphics characters which are used by the (few) games – there is no graphics mode apart from the graphic characters, so all games must be written to use the inbuilt character set.

Interestingly I have discovered an interesting restriction built into the BASIC. Certain parts of the memory map are not accessible using the PEEK (and I’d presume POKE) command. One thing I like to do with a new computer is write a small program which will let you interrogate blocks of memory. Doing this you can usually find where the screen memory lives, determine where BASIC programs live, scan the BASIC ROM for keywords (so you know what the language can/can’t do) and maybe even find the character bitmaps. With the Aquarius though, PEEKing some locations give an error message – I am guessing this was intended to hide the BASIC ROM from prying eyes. I guess that means I’ll have to try my hand at writing some Z80 code to do my snooping…
BTW, so far I haven’t been able to figure out how to edit a line of BASIC short of retyping the whole line and on a chicklet keyboard that gets old fast! If anyone reading this has an Aquarius manual they could scan in for me I would be most appreciative.

A couple of days ago another parcel arrived at ‘Chez arb’, this time containing some Mattel goodies – An Intellivision Intellivoice module plus games and a Mattel Aquarius computer! This was the first Aquarius I have seen on eBay Australia and I managed to win the auction at a very reasonable price for such a rare machine.
Interestingly, the Aquarius was actually designed and built by Radofin, a name which I am familiar with duue to my obsession with the 1292 Advanced Programmable Video System. (The 1292 was an early cartridge-based game console which was manufactured by a number of companies, including Hanimex, Acetronic, Prinztronic, Fountain and Radofin – one day I will get around to writing an article or two about this great system.)

From the information available on the net, only around 20,000 Aquariuses were ever made, with a production run lasting from June 1983 to October 1983 – five months! It seems the Aquarius was underpowered and overpriced and died a quick death.

I’ve only hooked it up to the TV once for a quick looksee, so I really don’t have much to say about it yet. The keyboard is a chicklet-style keyboard, with an overlay containing BASIC keywords over some of the keys. In a fashion similar to Sinclair compters, you can use shortcuts to enter most BASIC keywords, which with a chickllet keyboard is a welcome addition – these things are not made for touch typists! The memory is a whopping 4 kilobytes and the inbuilt BASIC is (naturally) a Microsoft variant. The seller had a single game cartridge for the Aquarius which is a port of an Intellivision game called AstroSmash. The graphics are very primitive, especially compared to the Intellivision which was already a well established system by the time the Aquarius came out. I am sure the poor graphics contributed to the system’s early demise.

Overall the Mattel Aquarius is a nice looking, if severely underpowered computer. I’ll now start to hunt for information on the web and hopefully get a bit of time to play with this interesting piece of computer history…