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QL vs BBC vs Amstrad 464

Posted: Mon Nov 04, 2019 3:36 pm
by Andrew
Sinclair QL vs BBC model B vs Amstrad CPC 464

i do not understand how in the benchmark test QL was slower than Amstrad

https://youtu.be/Gj-DdSD6C3k

Re: QL vs BBC vs Amstrad 464

Posted: Wed Nov 06, 2019 9:31 pm
by Peter
My first guess: Maybe integer calculations, not using integer variables on the QL, but on the Amstrad.
Their rating looked arbitrary, e.g. for graphics they assigned just one point difference, although the QL was much faster.
And they didn't value the microdrives over cassette at all.

By the way, this is not off-topic. You might get more feedback under "General QL Chat".

Re: QL vs BBC vs Amstrad 464

Posted: Thu Nov 07, 2019 12:12 am
by 1024MAK
The trouble is, we don’t know the exact set of benchmarks that were used.

I’m guessing that this was all the standard benchmarks rolled into one program. The whole point was to run the same program on each machine. So they were all likely using floating point variables. As that is the most common type in most versions of BASIC.

The Beeb is known for having one of the fastest BASICs of the 8 bit micros. And it’s also quite speedy when writing to the screen if in MODE 7 (the teletext mode). It’s not bad in the graphical modes either. The Beeb normally starts up in mode 7.

The 6502 runs at 2MHz when accessing ROM or RAM, including no slowdown when accessing screen RAM.

The Amstrad CPC uses a 4MHz Z80 and was developed after the Beeb. The designers put a lot of effort into getting the most out of it. So it’s fairly fast at printing to the screen. And it’s BASIC is fast as well.

Although the QL has a 68008 running at a little under 8MHz, multiple accesses are needed to get the data from RAM. As the bus width is only eight bits. And the 68008 has to wait if the ULA is drawing the screen.

Mark

Re: QL vs BBC vs Amstrad 464

Posted: Thu Nov 07, 2019 7:54 am
by tofro
From a pure hardware spec perspective, the QL should have been marginally faster than the Beeb or the Amstrad. Early QL Basic, however, has always been known to be bug-ridden and slow. This improved over time - Probably the QL would win today. S*Basic on SMSQ/e, on the same hardware, is way faster than old QL Basic.

Re: QL vs BBC vs Amstrad 464

Posted: Thu Nov 07, 2019 11:28 pm
by janbredenbeek
Peter wrote:My first guess: Maybe integer calculations, not using integer variables on the QL, but on the Amstrad.
Their rating looked arbitrary, e.g. for graphics they assigned just one point difference, although the QL was much faster.

Remember that using integer variables on the original QL had no speed advantage, it was often even slower. When calculating i%=i%+1 the '1' was stored as floating point, so i% had to be converted to float first and after the addition back to integer. This was the reason why Laurence introduced 'integer tokenisation' in Minerva so that constants were stored in integer format where possible so the maths could be integer too. SuperBASIC even had two reserved token codes ($89 and $8A) for this but they didn't make it to the Sinclair ROMs.

Overall I had the impression that the QL's math package was quite fast compared to 8-bit machines even for floating point, partly thanks to the 68000's MULx instruction (you needed 4 of them for a FP multiplication as these have a 32-bit mantissa, but this is probably still faster than having to do it bit-by-bit on the 6502 or Z80).

Jan