43

Sinclair didn't always use the Z80 for its computers. The MK14 computer, sold in kit form (like the ZX80 was), used a National Semiconductor INS8060. The ZX range of home computers have a video display hardware that is very closely tied to the architecture of the Z80. On the two first models, ZX80 and ZX81, the video display hardware was kept to a minimum, ...


36

These tricks are usually done to increase speed or reduce space. For most (especially Microsoft) BASIC, constants are stored within a tokenized line as ASCII (as entered), and converted to a floating point number every time they are evaluated. This is a time consuming process. Assigning the number once to a variable to be used thereafter will skip this part ...


34

Contrary to other answers, obliging the user to enter BASIC tokens directly doesn't really save meaningful amounts of RAM. Many of its contemporaries such as the BBC Micro had BASICs where you typed keywords in full which were then immediately tokenised when you pressed enter. If anything, tokenised Sinclair BASIC generally had longer byte sequences than ...


18

A purely speculative answer: it's a user experience improvement. The ZX80 is unable both to process keyboard input and to maintain a stable display. It has the Z80 itself step through display bytes and programmatically generate vertical syncs, which requires it to be in a loop that is tightly synchronised to the video signal. It's able to do a fixed-length ...


15

The answer by Raffzahn is very good, except that I disagree that ZX80/81 background is all that important and I also feel he missed one important trick. I personally know most of these tricks from studying BASIC loaders for ZX Spectrum games. You see, yes, Spectrum has more memory, but when the machine code program is loaded, it was absolutely not uncommon ...


7

I wasn't necessarily easier - it was down to money. Remember these were the days when the single most expensive component of a computer was its memory. For many micros of the time, a simple memory expansion kit would cost more than the base model machine itself. Sinclair was very clever at squeezing a working system into the smallest possible memory ...


7

I know it's bad style to answer ones own question. Still,I feel the need to publish my findings (*1): Over the last 3 Month I've been able to collect serial numbers of 28 different Z88, with 62271 being the largest. Using the so called German Tank Formula as traal had suggested yields 64494 as a result. So it might be safe to assume that there where less ...


5

The easiest way to tell is by looking at the traces on the board. If they look curvy, as though hand-drawn, it's an issue 1. If they're in more or less straight lines, it's a 2 or 3. Seeing as issue 2 boards are exceedingly rare in the wild, it's almost certainly the latter. You can confirm this by looking for the issue number on the board, which should ...


4

Pokemon on the German ZX Forum has designed a number of video improvement circuits (ZX81CPP, ZX81SCP) that allow connection of a composite video monitor and produce a crystal clear picture once properly adjusted. https://www.sinclairzxworld.com/viewtopic.php?f=8&t=841&sid=9e23e93b43bfcc0bb782a80803430e70 The circuit basically completely re-creates ...


2

The 128K model (and its Amstrad made successors) did use a tokenizer in 128 Basic mode. In this mode, you had to type in the command lines in full text, then syntax checking was made upon line validation rather than on the fly as with 48 Basic, and if correct, then the line was tokenized, then either stored (if preceded by a line number) or executed. So ...


1

I am in doubt it was due to a special technical reason. Finally I can not judge really but I am convinced there are a couple of advantages of this design. My first computer/programming experience was with ZX Spectrum+. In contrast to its predecessors the keyboard of this model was outstanding till today. It was very well designed and very responsive. For ...


1

My bet is because of small amount of RAM in BASIC. You need to take in mind there is the framebuffer, heap/variables and stack. If the code where represented as ASCII text it would be considerably longer. I often hit the memory limit in BASIC while writing small games in my early days of programming. For example this (first BASIC program I found in my ...


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