Old Skool Blog

After spending way more time than I really would have liked, I managed to get an image from my ZX80 on the LCD TV. Unfortunately, the ZX80 is an NTSC model, while my LCD TV is, naturally, PAL so I get a rolling picture, which is hardly usable. I then dug out my PCI TV tuner card, found a spare slot in my PC and tried to get the card working. However, it appears that the card is dead - I could not for the life of me get anything working with the card. Upon further reflection, using my PC won’t really be a viable long-term solution owing to its location, which just wouldn’t be terribly convenient. So I have decided to get a USB TV tuner for my Mac.

The tuner I have decided on is the Miglia TVMax, which has built-in hardware compression and a nice array of inputs which would make it almost ideal for my needs. Now I need to find a reputable online retailer because the NTSC model is not available here in Australia. So who would you recommend? Preferably someone who ships internationally.

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…

A new addition to my growing collection of old skool computers arrived last week - a Sinclair ZX80. This is the second ZX80 I have managed to win on eBay, unfortunately both are NTSC models and my TV doesn’t do NTSC, so I am considering modifying one of the ZX80’s to do composite out. It should be possible to grab the video from the modulator’s input - I just hope I don’t blow something up in the process!
I will try to post some pictures of my new ZX80 as soon as I figure out a way to get it working on my TV. I could have sworn my TV was multi-format, but I must be mistaken…

BTW, sorry for the lack of posts recently, but work and health issues have been piling up and I kinda let this site slide. I’ll try to be a bit more regular in future.