Questions tagged [zx80]

The Sinclair ZX80 was a low cost home computer introduced in 1980.

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14 votes
4 answers
3k views

Why does Sinclair BASIC have all of the characters twice in the token table?

I'm looking over the table of tokens for Sinclair BASIC and I'm struck by two things. One is that it's not ASCII. Some parts are in the same order, but others are not, so it would seem conversion is ...
13 votes
2 answers
952 views

Simple doubling of ZX80 RAM

Many moons ago when I owned a ZX80, I remember (or possibly mis-remember) seeing a simple way to double the RAM to 2K by simply piggy-backing two extra 1Kx4 chips on top of the existing two (with pin-...
9 votes
1 answer
1k views

How did the ZX80 RAM pack use DRAM?

The Sinclair ZX80 was the most popular personal computer in Britain at the beginning of the 1980s, due to its low price which was enabled by extreme minimalism; it consisted of not much more than a ...
9 votes
3 answers
546 views

ZX Spectrum - guidelines for porting to PC and more are appreciated

I want to make a surprise for my father. Back in the 80s my father made a game for a custom clone (called Santaka) of the ZX Spectrum. I have all the digital files needed for it to work, but I'm ...
25 votes
2 answers
4k views

How did the ZX80 store both a useful program and screen memory?

I have a vague recollection from my earliest days that the ZX80 only shipped with 1K of RAM. If this RAM was used to store both the program and the contents of the 32x24 screen, wouldn't that mean ...
16 votes
3 answers
2k views

Is there any significant difference in Sinclair BASIC of ZX80, ZX81 and ZX Spectrum?

I'm trying to write some programs from an old magazine that were specified to run on an ZX80/ZX81 but I'm using a Sinclair BASIC interpreter for the Spectrum. Is there any significant changes in BASIC ...
2 votes
1 answer
194 views

Did the ZX80 RAM pack pass the expansion bus through?

The ZX80 only came with 1K of RAM, which had to be shared between program and screen memory, so many customers bought the Sinclair 16K RAM pack, which plugged into the expansion bus (the edge ...
29 votes
3 answers
6k views

Why did the ZX80 CPU run at only 3.25 MHz?

The Sinclair ZX80 used a Z80A running at 3.25 MHz. But this chip was rated for 4 MHz. Why was it run below rated speed? Apparently the master clock in the machine ran at 6.5 MHz, so the CPU clock ran ...
7 votes
1 answer
682 views

Why is ZX80 much faster than Spectrum on Rugg/Feldman benchmarks?

If you look at the results of the Rugg/Feldman benchmarks, shown in this Wiki entry, you'll see that Sinclair ZX80 is much faster than Sinclair Spectrum on all tests despite the fact that both ...
13 votes
2 answers
2k views

Why does the ZX80 not produce a steady display signal?

As Tommy pointed out in my question about BASIC tokens on the ZX Spectrum, the ZX80 is a computer which does not produce a signal which is displayed steadily on the TV. It looks to me as if the CRT is ...
11 votes
3 answers
932 views

ZX80 BASIC checking free memory

Did ZX80 BASIC have a way to check how much memory you were using and how much was left? Or otherwise: if you were writing a program on a machine with the RAM expansion, was there a way to tell ...