Posted By
MMS
on 2022-02-14
16:50:03
 |  Re: A Plus4 rival twin brother?
@Litwr:
I was and still surprised, why the QL was a disaster.
Actually, QL COULD be a really good small office computer, and even the microdrive was a good idea, but NOT with that way. Every time it was stopped, it changed it's lenght, till Samsung solved the matter with the new drives (but it was already over for QL).
The Philips Compact Cassette was available since 1963, and the initial low quality was solved till the end of 70s. There were a big bunch of producers (BASF, SONY, TDK, just to name few), and that 3.84mm tape width was not too big (microdrive: 1.9mm, just the half), but was available on the market in bulk as a standard.
If you check how a microdrive look from inside, it becomer evident, that a 14mm thick infinite loop cassette could hold the normal compact cassette tape without problem, not to mention, that the high bias IEC-II chrome tapes were also available at that time (better frequency range, thus higher data compression rate is possible)
In fact, 1.9mm was OK for mono signal, but with the already available and good quality stereo heads they could store on a Compact Cassette tape two tracks (one track for the main program (eg. WordPro), the other for the data), and the drive could easily swich between the two. So one mechanism could be enough instead of the two of the QL, they could save on cost of mechanism. They could save on the cost of tape a LOT, as they could buy it from ANYONE (the 3.84mm thich tape).
https://en.wikipedia.org/wiki/ZX_Microdrive
The main problem was NOT that Microdrive media was thin, but they sacrificed the available media on the altar of higher search and loading speed.
It had a 23 micron thick tape, while the C-46 and C-60 compact cassettes used only 16 micron thick tapes. The problem was the too fast acceleration and too fast stopping, caused the stretching of the tape, thus destroying the bits, made the media unreadible
(I think it was Samsung's solution too to slow acceleration down, and made the media more reliable, it became so relaible to able to read after 17 years of use).
With a little slower speed and movement, with a bigger capacity Microdrive could be a real BEAST MEDIA of the 80s.
The ZX microdrive was really, really fast. It took more tpye to type in the command and the name, than the loading speed. Sounds crazy, but true.
It had 15 KB/sec (or 120Kbit/sec) load speed and the complete tape was winded based on the built-in file catalog within 8 seconds (85KB capacity).
I think if THAT speed would have been available for C16, I could give my half arm or kidney for it at that time  !
Really, loading a game within 12-15 seconds, including rewind time? It could have been epic.
But 85KB was too small capacity. With a little bigger but still small tape size (70x60x14mm) they could get 200 KB/track capacity with 3.84mm tape (400KB per tape cartridge), with a high reliabilty (with half search and loading speed). Mircordive size was tiny, just 44 mm × 34 mm × 8 mm.
I think instead of 15KB/s a 6-8 KB/sec loading speed from tape could be still very acceptable (much higher than the 1541 or 1551 speed, even faster than the highly praised Apple II's 4KB/sec speed of floppy, developed by Steve Wozniak himself !).
Yeah, the seach speed of the file could be a little slower than floppy, but the higher capacity medium with a slower search speed could be 20-25 seconds search time with the help of a REAL catalogue, then 10 seconds load time for a 64KB file? Half minute loading time sounds great. We could not match this with our HER turbo.
Most of the ppl do not know, that QL was one of the first 32bit (!!!) home computers, as the 68008 CPU was internally 32 bit at 7.5MHz, while the external was only 8 bits (to save motherboard cost).
In your PI calculation benchmark test QL was 4.7x faster than Plus/4 with switched off screen, maximum speed.
Introduction price of QL was Ł399, while Plus/4 was $299 (Ł250?). so if you check the performance/price ratio, you see the winner.
QL's 640 KB expandability of RAM was a beast at that time, as IBM PCs have this memory only, for a much higher price. Plus/4? not expandable (easily)
The 512×256 pixels resolution (in 4 colors) could be great for text editors and even GUIs (they had it, before Apple Macintosh or Amiga). Unfortunately the color selection was really bad for that, as bad as CGA. (black, red, green and white).
A selectable 4 levels of grey (like later the ATARI ST monochrome monitors) could make it a more calming and professional experience. but QL did not have a color palette, just few pure RGB colors. Plus/4 is a real winner here.
High resolution mixed with 8 color only, using 32KB RAM? Sounds to be a bad combination.
VGA with just 64K could make epic games on 320x200, 256 colors (Hero's Quest, Dune, Day of the Tentacle, Wolfstein 3D, Doom, Tie Fighter and so).
But we all know, Sir Sinclair did not like games.
Compared to Plus/4, QL came with a really great Office suite (to make it biased: it could be really hard for single programmer to compete with an already great company). QL's office suit was made by noone else, than PSION, that later created the PSION Digital Assistant, and later the EPOC opysytem, later evolved to Symbian of the Nokia (I still think late versions like Anna/Belle were better than Android, just my 2c)
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