The ZX80 reaches 44 plus the new Chroma 80
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- เผยแพร่เมื่อ 6 ต.ค. 2024
- January 2024 is the 44th anniversary of the launch of the ZX80. Coinciding with that is the launch of the Chroma 80 expansion which adds some neat features to the ZX80. I have a look at the ZX80 and Chroma 80, along with some software that pushes the ZX80 beyond what the engineers dreamed of.
The Chroma 80 is available from www.fruitcake.plus.com
Great ZX80 news Wrangler Amiga! Paul Farrow's ZX80 work is marvelous! Warm regards and best wishes
Thanks, you too!
WOW! COLORS 44 YEARS AFTER! I WONDER IF WE CAN HAVE SOME SOUND AFTER 44 YEARS MORE!!! =)
Limited sound capabilities for the ZX80/81 were made possible back in the 1980s. I can't remember when colour became possible on the ZX80/81, but "high resolution" graphics were certainly available back in the day. It's amazing what people have been able to achieve with the limited hardware and a lot of ingenuity.
SYNC The Sinclair ZX80 magazine pages 24,25 has the schematic of the ZX80.
The oscillator runs at "6.5MHz" which is divided by 2 to make "3.2MHz" somebody is rounding off a lot. The marking on the X1 in the one I have reads "6.5MC".
I was one of the very first people to own a ZX80 that was pre-ordered as soon as it was advertised and it was delayed for months, but at 10 years old I loved it when it finally arrived, firstly I only had 1K, later expanded to 16K. Yes, I remember the screen flickering off whenever it processed anything with the entire processor needed just to display the screen. Yes, before long clever programmers used exact software timing to process other code when the screen was updating outside the border allowing flicker free games, this was added with interrupts on the much more popular and mass produced ZX81 with it's slow mode making it much easier to program games.
The entire processor was not required to display the screen but because the character generator and Z80 shared the address and data bus. As such, the character generator had to stop when the Z80 needed to access the address and data bus. The daft "experts" explain why the screen flickered shows how many myths are still quoted as fact.
@@bertram-raven It's been a long time since I really used my ZX81, but as as I recall, the Z80 CPU was responsible for all of the organisation for the display on both these machines, so it wasn't just the bus contention that slowed it down.
@betram-raven: keep your comments civil and refrain from tolling or they will be removed.
CPU refresh cycles are used (in a way the Zilog engineers hadn't intended) to read character bitmaps to generate the screen. Without the CPU, there would be no display, so the CPU absolutely is used to generate the display on the ZX80.
The screen is only sort of limited to the built in ROM. Using some very hard to understand code and an assembler that I had for my ZX80, I could make it do pixel graphics 320x160. You needed the 16K RAM expansion to put it to much use and the Z80 was spending all of its time making it happen. It was also possible to get the ZX81's ROM to work in a ZX80. In the one I had I added a EPROM that was a total of 16K bytes and a switch. 4K of the EPROM was the ZX80's ROM. 8K of it was the ZX81's ROM and 4K did nothing. I could power off, switch the switch and power it on as the other product.
What a lovely upgrade!!! Happy New Year!
And to you too, sir!
Happy New Year!
Wow! Color on a B/W Sinclair, very cool!
I bet it was something to have these back in the 80's when computers were new. I had a CPC 464 growing up but computers then were widespread and the CPC was old hat.
Yes, back in the late 1970s and early '80s, home computers were either primitive machines for electronics hobbyists, or really expensive boxes that most people couldn't afford, and more importantly, didn't really understand. Businesses sometimes used microcomputers, colleges, universities and some schools had them, but they weren't that common in the home. So being able to buy a cheap micro that you could use to write your own programs, play games and all sorts of other new and exciting things, was a big step towards democratising home computing for the masses in the early '80s.
A lot of computers only had dumb terminals so this wasn't that bad actually the average person didn't even have a computer until the 90s only in the early 2000s. did most people own a pc apart from the very poor or old
My best friend got a ZX-81 as a gift when we were in high school and we both ended up with accidental careers.
Doing what?
@@Saturn2888 we both ended up computer programmers.
Great video Wrangler 👍🏻 Would contact you over on EAB.. But now it’s owned by RetropassionUK and users being perma banned for no reason…😤🙄 Oh well… Look forward to your next upload 😉
People are banned from forums for a reason, even if you're not privy to that information. Just because you don't necessarily know or agree with those reasons, doesn't mean a ban is unfair.
This is the best ZX80 review ever. Insta-subscribe.
Only clive sinclair could get away with selling computers with no sound or colour. glad i skipped these years ago lol
Then when they did get sound and colour, it was just a beeper and basic colour clashing. But at the price the computers sold for people were willing to put up with that.
...at roughly a quarter the price of _any_ other computer in the world... just, y'know, to put things in perspective. And it launched the IT careers of thousands of guys 'n gals who are now approaching retirement - me being one of 'em. The user guide was about 3cm (well over an inch) thick and taught BASIC and Z-80 machine code. Don't get nuthin like that today!
There were dozens of personal computers which where the same. Sir Clive just followed the trend to make it cheap and accessible.
But it was a fraction of the price of the alternatives that did have colour and sound back in early 1980, even computers that didn't like the Commodore Pet cost what would be considered a small fortune in those days, the low cost made the ZX80 assessable to a lot more people. In early 1980 we had consoles like the Atari 2600, but hardly anyone had a home computer and most didn't consider it as something important that you'd be willing to spend large amounts on. Later in 1980 we saw prices start to come down generally and technology moved very fast, the Commodore VIC20 had colour and sound, far superior to the ZX80 was released at 3 times the cost.
Actually there were a number of earlier microcomputers that had similar or even greater limitations. Very early micros didn't even have a keyboard, and relied on entering instructions via a series switches on the front. Such machines were oriented toward electronics hobbyists, engineers and the like. In comparison to such early machines, the ZX80 was a HUGE step up. What Sinclair did was make a usable, entry level computer that people could understand computing without spending a fortune. Most home computers were several times the cost of a ZX80.
Please stop retelling the myth of the Z80 being used to generate the display.
The entire processor was not required to display the screen but because the character generator and Z80 shared the address and data bus. As such, the character generator had to stop when the Z80 needed to access the address and data bus. The intrinsically daft way "experts" explain why the screen flickered shows how many myths are still quoted as fact.
Also, the description of running code in the frame refresh is massively oversimplified to the point of being nonsense. A case of "close but no cigar."
Yes, I knew the hardware backwards - both the ZX80 and ZX81.
Please explain which chip was responsible for organising what is to be displayed on screen, and where abouts. As I recall, that would be the Z80 CPU, which is what slows the ZX80/81 down, not just the bus contention. Unlike the contemporary Atari 8 bits and VIC 20, the Sinclair machines had no separate graphics controller, but they all had varying amounts of bus contention. A quick "Poke" on the Atari 800 to switch off the display, and CPU code would run much faster for that very reason. But the graphics chips took a huge load off the CPU, unlike in the ZX machines.
A slight correction: On the ZX80, the processor had to be executing a string of NOPs in order for the display stuff to work. The Z80's timing was the timing that made the byte fetches and the lookup in the character table. The program counter was set to the area in RAM that held the screen ORed with 0x8000. At the end of the scan line, the memory refresh register would have counted up enough to cause the INT to happen. The INT went into software that did the sync pulses and then went back to doing the NOPs.
@@another3997 The ZX80 had no bus contention. The Z80 its self was extremely busy to do the display. The bus from ROM and RAM hooked to the Z80 through 8 each 1K resistors. 8 open collector gates could pull the data bus going into the Z80 so that it would see a NOP instruction. (7 sections of U14 and one of U15)