Exploring a rare Chinese home computer! Part 1: inspection
Vložit
- čas přidán 3. 06. 2024
- I know I'm making too many part 1s without proper followup. That's partly because the development of HEC is often paused by some replacement parts that I need to fix a hardware bug, but takes days to arrive. Every time that happens, I try to do a video on some other topic. But I can promise that there will be a part 2 of this series. Because the inside of this machine is really out of the ordinary.
- Věda a technologie
"Cass Rem" is Cassette Remote - yes to control the motor. It was often the smaller plug on audio equipment.
Ah, that's it! I knew it was some kind of motor control but couldn't figure out what 'Rem' stands for.
So, as I said the TP 804, is a Z80 based educational computer with 64K RAM running BASIC from the university of Beijing. The TP 801 was a single board computer in the style of the KIM- or the Intel 8085 board, with 7-segment displays and a hexadecimal keyboard, and the TP 803 was the predecessor of the TP 804.
When googling for TP 805 add "BASIC" to the search words, that is how I found other Chinese sources.
Absolutely love this video's presentation and editing. Please keep it up!
CASS REM means Remote. This is a relict of the cassette tape recorders from the 80th. A microphone shipped with the recorder has got a 2.5mm connector that is connected with a simple switch in the cheap microphone to stop and restart the recording.
Yes, I figured that out.
Clearly the people who made this had a no-screwing-around policy 😆
"CASS REM" is indeed to control the motor of the cassette deck motor. 😊
"Cassette REMote", maybe? 🤔
@@Zhixalom Yea, the signal is officially called "Remote".
I think basically originally it was used with push buttons on microphones and sometimes even foot switches for dictaphones. Like when doctor recorded journals on to tape.
@@MariaEngstrom I still have my old trusty Grundig tape-recorder, which I used with my ZX Spectrum back in the '80s.
It has the same arrangement of 2 mini- and 1 micro-jack named EAR, MIC and PAUSE.
However, in the manual I found online, it refers to the micro-jack as REM.
I've also noticed that the Commodore Datasettes also have a pin in their proprietary connector for pausing, or probably simply temporarily cutting power to the motor.
- So, basically the same mechanism all in all.
Thanks for the first look Andy.
I have this machine, and also have tp-801 and tp-803. TP-801 is the first Chinese single board computer.
I have both TP-801, TP-803 and TP805. TP-803 embeded a BASIC interpreter in it's ROM, but TP-805 don't have. The clock circuit design of TP-805 maybe have some problems. It generate a 4Mhz video signal instead of 3.581Mhz. So if you connect TP-805 to a morden monitor, V-Sync will be lost. I simply replace the original 8Mhz crystal oscillator with a 7.16Mhz to solve this issue.
Tip: do not read this comment it's a spoiler (I guess once anyone reading this would have read the comment so... yeah)
good luck!
Try the other two rubber feet, there can be screws.
UKNC has 2! 8mhz Pdp-11 compatible processors. It was the most fabricated computer in USSR (near 300k), but it was unsoldable ( it was made only for school and office use, simple man can't buy it in shop). But USSR made another pdp-11 compatibles, like BK-0010, BK-0010.01 and BK-0011. There are more simple, than UKNC, had only 1 processor with lower clock frequency (3 mhz in bk-0010, 0010.01 and 4 mhz in bk-0011), smaller graphic capabilities, but it was soldable (price was 650 soviet rubles).In USSR also was made wery rare (800 things only) domestic pdp-11 compatible, Union-Neon PC-11/16 (Союз-Неон ПК-11/16), it was most power in pdp-11 compatibles domestic line, it's graphic compatibility was near amiga 1000! In youtube you can watch some reviews and demos, but there are few of them in Russian, even in English. Sorry for my bad language.
That is very interesting information! I didn't know that UKNC was unsoldable and said 'The Soviets sold the UKNC to homes' then edited it out because I cannot find proof of this. I guess that saved me from making a correction video! Also thanks for clearifying the difference between the UKNC and BK-series. I knew nothing about the Neon PC-11/16 and would like to do more research on it. (I cannot speak russian so can you point me to some information in English?)
That's interesting man .
@3.52 you show the side of this computer, and you can see there is a split between the front keyboard part of the case, and the back main case. this suggest the two parts are somehow detachable. Perhaps there are two screws underneath the two plastic feet that can be loosened, and then maybe the keyboard part can be removed somehow.
Another place to look for screws is if you look down into the cartridge opening. But all this seems moot, because you claim you HAVE opened it, and will show us the inside in Part 2.
Normally A computer like this has an RF modulator with an RCA (Tulip) plug, but perhaps it is inside, and a short cable plugged into the RF modulator connects it to the "TV UF" 2.5mm jack plug (probably UHF channel) and the other 2.5mm has a composite video signal. by the way an expansion Bus connector is quite often implemented with an angled pin header connector, not rare at all. the AC supply is 220V 50Hz, which sounds european, and probably internally has a power supply that delivers 5V at 2A normally this isn't labeled outside, but 2A at 5V seems reasonable to me for a Z80 based computer.
The pictures you showed were IMHO simply of an Intel 8080 based single board engineering reference computer, and it should have nothing to do with this computer. I'm always interested in singular newly discovered computers, so this is interesting. I know of no Chinese "home computers", only those from Hong-Kong, so yes, it is interesting.
P.S. PDP-11 single chip CPU's were quite common in the west, as did PDP11 multi-chip sets.
I wonder if there are screws under the back feet, and the front just hinges or is clipped together.
That is what I thought too, as you can see the keyboard section split.
Chip shortages and export bans sure affected the Chinese computer market. What is this 1000 nano meter!?
It's an early Z80 based system. From 1983 I think.
Oh this is not 1000 nano meter! The Z80 is manufactured in 4um process so it's technically 4000! But, guess what? It's manufactured before the ban!
@@andyhu9542 I did not think that I would be even close. Not bad, hope there will be some kind of resolution of the situation. Or just start producing the 1nm chips.
As soon as I saw that keyboard and cartridge slot I thought "Color Computer", but the CoCo had neither a parallel port nor a dedicated expansion port. I'm very curious what CPU and support chips are inside it. Is the resemblance coincidental or did someone decide to improve on the CoCo design?
Nope, it's not a Coco ;)
Cass Rem must mean Cassette remote