Questions tagged [sinclair]
For questions regarding computers made by the Sinclair group of companies: Sinclair Research, Sinclair Radionics and Science of Cambridge.
33 questions
11
votes
4
answers
1k
views
Function to return free memory in Sinclair ZX Spectrum BASIC?
Sinclair BASIC doesn't have a FRE() function, which on other systems typically returns the number of memory bytes currently unused by BASIC. I'm looking for a way to find that value.
The system ...
- 22.8k
8
votes
2
answers
2k
views
What does Spectrum BASIC have that ZX81 lacks?
The Sinclair ZX81 has 8K BASIC interpreter ROM; the Spectrum has 16K. What extra features does the Spectrum put in the extra 8K?
The most obvious thing is commands for color graphics, which are absent ...
- 65.3k
11
votes
1
answer
1k
views
Using Sinclair ZX Microdrive is it possible to random access a text-file?
I wish to build a small database using Sinclair ZX Microdrive: one can think to create a text file using some simple BASIC. For simplicity let's say the record is 512 bytes in length, i.e. the same as ...
- 534
8
votes
3
answers
426
views
What is the correct power supply for this SD card/cassette reader for Sinclair computers?
I bought this some time ago, but I did not keep the power supply with it. It does not have any product name on it, and I can't locate the correct information. What is the correct power supply and what ...
- 283
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 ...
- 22.4k
5
votes
1
answer
344
views
How many units of the ZX81 RAM pack were sold?
The Sinclair ZX81 was an extremely popular low-cost home computer, on strength of price, being a computer for less than 100 pounds. It sold over 1.5 million units, according to https://web.archive.org/...
- 65.3k
34
votes
8
answers
5k
views
What made some 8-bit BASIC interpreters especially slow?
Most 8-bit systems had a BASIC interpreter that ran at a rate roughly commensurate with the CPU type, speed, memory bandwidth and interrupt status. Some systems, however, had interpreters that ran at ...
- 22.8k
14
votes
3
answers
2k
views
What was Sinclair's intention with the Microdrive?
The ZX Spectrum was announced with support for both standard cassette tapes and Sinclair's new Microdrive format -- although the latter wasn't released for another 17 months.
Given that the necessary ...
- 157
16
votes
3
answers
3k
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 ...
- 161
3
votes
2
answers
638
views
Spectrum 128K +2 Power Supply Buzzing and over voltage
I've seen a similar question to asked here but but I'm not sure it fully addresses the issue I'm having. I'm using a PSU the same as this one from the 128K +2
According to this site, this PSU ...
- 131
9
votes
1
answer
445
views
Can the TMS1802/0102, or specifically the Sinclair Executive calculator, handle an attempt to divide by zero?
There's a sort of urban legend among people I've spoken to about Sinclair that the Executive calculator can't divide by 0. Specifically, if you do this then it goes into a busy loop, cannot be used, ...
- 953
9
votes
1
answer
469
views
Can you switch the ZX81 ROM to RAM w/o write protecting it and still use ZX81 BASIC?
I built an external 8K RAM circuit that replaced the 8K ROM of Sinclair ZX81 and I also pulled out address lines from the ULA (dogsbody) so that character generation worked. I wrote a small machine ...
- 505
19
votes
1
answer
4k
views
Why does the ZX81 not have user definable characters without extra hardware i.e. why could the character ROM not be in RAM?
I know you can use different parts of the 8 KB ROM in Sinclair ZX81 as character ROM by changing the I register, but it seems one cannot change the I register to point to RAM [and have character mode]....
- 505
25
votes
4
answers
6k
views
When did half-bad RAM chips stop being available?
The ZX Spectrum sold with either 16 or 48K RAM, necessitating an optional 32K memory bank which was achieved in a characteristically (for Sinclair) cleverly frugal way: with half-bad 64kbit DRAM chips,...
- 65.3k
2
votes
0
answers
158
views
How many people were employed in the UK making Sinclair computers?
According to Wikipedia Sinclair Research had only 140 employees at its peak in the 1980s. I was surprised the number was so small for a company that sold something like five million computers, then I ...
- 65.3k