The Jet was a Romanian Spectrum clone computer built in a telephone case! You can see the handset housing and the numeric keyboard replaced with black plastic masks.
The keyboard was made of printed pieces of paper inserted in transparent key-caps.
This system has been deeply modified by the user(s).
Zeno Mateescu, who owned a JET, reports:
The whole computer was more a HC-85 clone, designed more specificaly for computer games. That's where the name came from: JET-EM Aparat pentru jocuri pe ecran TV - machine for games on TV screen - if I remember well. It is indeed a Sinclair ZX Spectrum compatible computer. It didn't had any joystick connector (kempston or any other joystick) so I had to modify it to use a joystick. Another interesting thing about JET was that you
couldn't hear the program that was loading from the tape. On HC85, for example, you could hear that, let's call it noise, when loading the program.
- pal video signal: PAL: 1 Vvv / 75 ohm;
- radio signal: 1 mVeff / 75 ohm;
- the signal for the cassete recorder: 05 Vvv / 1 Kohm
Input signal from the cassete recorder: min 50 mVeff
Internal beeper: min. 55 dB SPL
Contributors: Costel Dumitru
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I started my epic IT journey with one of these, and it will always hold a special place in my heart. I actually still own it, and it still starts up (haven''t tried any programs though as I don''t have the cassette tapes anymore).
Contrary to what some of the comments here state, the processor was perfectly fine and useable, despite being a reverse-engineered clone of the Z80. I played countless games on it (including the ones with custom loading procedures), wrote and ran numerous programs in BASIC and assembler, even loaded a simple version of PASCAL.
It''s possible some of the "JET" clones on the market were actually fakes, as it was common in Romania of that time to take the case of an existing computer and then add or tweak the internals$ that would explain the poor experience some other users have seen. Mine worked perfectly fine for everything I ever threw at it, actually I lately won a HC-90 during a computer programming contest and it was significantly worse in all aspects $ buggy loading from tape (kept R Loading Error''ing), non-working keys, insane noise when loading programs from tape (whoever thought that was a useful thing to have?!).
The keycaps were by far the best on the market among all Z80 Romanian clones (HC, CIP, etc.) as they had the text printed and covered by a plastic cap$ it means they are still readable and in great shape decades later, as opposed to the others which had missing text soon after purchase and later would turn into "blank" keyboards.
The main disadvantage of the machine was the lack of native extensions $ while the HC benefitted from the Interface 1 and 2 add-ons, which enabled joysticks, floppy disk drives and even networking support (!), on the JET that all had to be done "the hard way". Mine only had a Sinclair Joystick extension to the side, which required some soldering and case modding, but it worked nicely afterwards.
Another interesting fact about the JET was that it was capable of reading several different tape "styles" (programmes recorded with different machines were rarely compatible among them due to the speed and amplitude of the tape signals), all it took was slight tweaks to the tape head. The CIP was also pretty good in this regard, but the HC was absolutely terrible, refusing to load any programme not written by its own hardware.
Indeed it was slow, I think due to a 2.5 Mhz CPU instead of the standard 3.5 Mhz for HC-85. I owned one and was driving me mad for not being able to load the "nonstandard" games. How can I define them? When loading BASIC programs, the screen flickers in a specific way - it loaded such programs. More recent games however, used their own loading routine, which flicked the screen "differently". They were probably heavier on the CPU, ''coze they didn''t load on JET.
Finally I gave up, sold it, added some difference and bought a HC. What a difference!
Saturday 8th September 2012
BUILT IN SOFTWARE / GAMES
QWERTY mechanical 40 keys
MME 880D Zilog Z80 Russian clone
48 KB + 16 KB masked by the ROM
16 KB (Basic + O.S.) + 4 KB (Unknown)
32 x 24
256 x 192
8 with two tones each (normal and bright)
1 voice / 10 octaves (Beeper)
SIZE / WEIGHT
358 x 238 x 80 mm / 3 Kg max.
RF video out, RGB out, expansion port (not connected), tape-recorder (In, Out, Rem), external loudspeaker
Built-in power supply, 220 Vca + 10%, - 15%, 50 Hz +/- 1 Hz, Max power: 15 W