Відео

„K“ stands for Keyword 😊

I recall getting a Sinclair Spectrum and opening it up to add an extra 48k of memory. The upgrade kit even came with a dummy practice chip.

well the two bits of installing cardboard explain the overheating

You can hear the spacebar rattle on this machine. I applied a small bit of lubricant to my wp-2's spacebar (chef kiss). It now sounds much better.

That looks so difficult but loads of fun Steve. So glad to have found this channel!

ua-cam.com/video/yZEi4t_JUpg/v-deo.htmlsi=_24TLRQ1trzJgBLU Borsh quake for sam at full 6mhz bet its faster than next at 7mhz

That was built at the Timex factory in Portugal. Lot's of Spectrum and Timex stuff came from there.

Chips that size are easy to hand solder - just forget the desoldering braid and use proper flux instead of a flux pen. They are so much easier to hand solder than the tiny surface mount resistors.

Some pic/mg 1.0 backplanes have isa and pci connectors and some of the pic/mg 1.3 backplanes have pcie x16

You need a backplane to get it to work The backplane needs to be pic/mg compliant, Yes pic/mg is a standard just as pc/104 is a standard

Lol that bat file that sits there looping through all the files on the disk is to make it look like your waiting for the computer to complete something while your at work back in the day

WTAF is a "ZEDX81"? Can people not read English? There is NO "ED" in the name of this minicomputer.

The Sinclair machines were such a contrast with Acorn's machines. The ZX81 and Spectrum are so very different from the Acorn BBC Model B and its descendants, not least because they had a fast, ergonomic dialect of BASIC with a built-in assembler.

BASIC simplifies everything. Assembly programming for the ZX81 is just as much of a shitshow as everyone says programming for the Atari 2600 is, very hard and not fun at all. Thank God, that ZX Spectrum is much easier.

Ya that glue is horrible in them will literally rust thru resistors on the board. Had this with 2 I recapped

I follow you on your ham radio channel and I have a question... I know this is an old video, but I also have a CDS 524 and I put in a Trident isa/vga card, my question is I have no video is there another step I'm missing , Thanks in advance!

I used to use one of these with a modem that had an acoustic coupler. I'd use it specifically from payphones for anonymity back in the day. Good times.

I finished two of these. They both work great. Had problems with the second board because I had cheaper sockets and was getting shorts. Eventually put Kawari boards in both and use Ultimate II plus carts for loading software. For Sixty Clone colors went with blue and purple. Your red one looks great.

Dude, I want that gateway that’s like the exact computer that was my first brand new computer from high school

Had a black one a while back and found it quite underwhelming. The case and design are nice, but the actual keys are very low quality, which of course is a major improvement over the chiclet keyboard, but definitely nothing I'd consider good or even mediocre.

The same problem with my c128, which was given to me by a colleague a few days ago, he said that it had not been started since 1990. The LED did not light up and the ignition switch worked normally, but one side did not conduct electricity like yours. thanks to you, I managed to put it together, soldered the contacts on the switch and brought it back to life! Thanks for the instructions and best wishes

The design of that pack is what you could politely refer to as "highly cost optimized" one of the reasons (apart from the iffy mechanical connection) that it's sometimes unstable is that it generates some of the RAM timing using RC networks driving regular 74LS series TTL chips. This makes it highly sensitive to a bunch of things like ambient temperature, the precise voltage of the 5V rail, which vendor supplied the chips and you looking at it in a funny way. That old school DC/DC converter didn't help either - it was needed because the 4116 needs +12V and -5V in addition to the +5V, but generated significant RFI - the metalized coating on the housing kept the radiated interference below the FCC limits, but still induced significant noise onto the internal signals. I looked at a bunch of these things back in the day, and although they did work most of the the ones I checked were running the RAM outside of it's timing specs - typically by violating the tRAH(min) spec. The use of disc ceramics in an RC network for delays is pretty sketchy, too.

The original UK versions didn't come with any of the shielding - just a plastic case

That took me back to 1981 ... have a subscribe.

Many years ago, I made my own 16K expansion. I think my circuit had fewer ICs. I made the multiple voltage part with a 555 timer chip. The voltages other than 5V drew little current.

Continuing my bad habit of commenting on old videos. In case anyone was wondering why RAMTOP was 17408, 16K of ROM = 16384. 1k of RAM is 1024. 16384+1024 = 17408. With the 16K RAM pack installed the internal RAM is disabled so RAMTOP is 16384+16384 = 32768. The reason you keep missing keystrokes is because the ZX81 uses the CPU to drive the screen so it's only available to work on other things, including scanning the keyboard, during the vertical refresh. It's easy to type faster than the computer can register your keystrokes. You'll learn to compensate with continued experience. Near the end of it's production Timex was able to sell the American version, the Timex Sinclair 1000 with 2K RAM, for $50.00 and still make a profit.

It's just ram and and 74ls xxx chips for the address decoder. You had to dind a way to support the ram pack so it didn't hang down on the edge connector. There were after makes 32 48 and 64k packs and some rs232, parallel , voice synthisizer , joystick interfaces and even a disk interface. I had a ts 1000 with 64k rs232 interface and disks running cp/m

Hi! I came across an old ibm ps/2 mod30. What version of ms-dos should i try to download? Is the default language changeable? Right now is telling me that I should insert a disk in German.

there are more ICs there than in the ZX81 itself ... LOL

I've got something from Sherwood as well. I recognize the name of the school. Darned if I can remember what it was. :)

A (possibly later) revision of this keyboard shipped with a Styrofoam block to support the circuit board.

Looking for schematic for this board

Impressively more complicated than I would have thought. Love hand drawn circuit boards. Any idea what it cost back in the day?

Thank you sir! A very informative and well made video. I was just installing MS-DOS for the first time since the early 1990s on my Pentium PC. It's been a while so this was not only a great nostalgic trip down memory lane, but also highly educational!

has anyone made a schematic of one of these? Might be cool to make a modern re-make to make it more generally available.

Looks like fun. The limitations of the Sinclair machines weren’t really the problem... it was the damned build quality! With an emulator, they become far more interesting than the old hardware would suggest.

Three and a half million wobbling little b*stards, that's what.

I’ve had the issue with floppy BIOS/ XT-IDE BIOS. I solved it by combining the floppy bios with the XT-IDE bios. I’m using a normal floppy controller and I use just the XT-IDE to carry both both BIOSes. Order needs to be Floppy BIOS first and then XT-IDE. You can glue both BIOSes with a HEX editor and then burn the ROM.

I had that RAM expansion and the connector was so bad that I did solder the expansion to the bus connector permanently in order to achieve stability. The bus connector weren't gold plated but tin plated and it didn't help a bit.

I think "Ingenuity" is the word you are looking for when it comes to the ZX81. Thanks for calling it the "Zed X 81" and thanks for the upload.....you have earned my sub.

In the early 1980s when computers were sold in every other shop, me and my Dad trailed through the town looking for one of these, we never found one. Looks real nice, wish we had found one.

Please tell me where I can buy a C64 board that has as many sockets as possible?

Great demo 👌 I have kontron dimm pc with the same processor IO controler ami bios, but when i connect Trident TVGA9000i model 7210 i couldn't get any output on a VGA monitor. On 8 bit (. disconnecting the ALE line from the ISA bus and connecting it to 5V) or 16 bit mode . Can pls confirm this cpu work with 8bit mode trident vga? If it work can you give me bios.bin maybe my bios file is corrupted.

Soon to come: 64-bit Edlin. (Actually, you may get the source code and compile it for whatever system you want.)

When this is all you had, then the ability to program really was something. I remember spending my entire summer school holidays back in 1981 learning to program in BASIC and write many games/programs for it. In retrospect, and with more powerful machines that followed, of course it's exceedingly bare bones in comparison, but back when it was either this or nothing, then you really did invest time and effort into doing all kinds of things, allowing a good chunk of your imagination fill in the gaps where the machine was wanting.

ZX81 n00b here: where’s the spacebar?!

6:30 maybe that could hold the ZX81 circuit board (as you implied at the start would have been a better design choice?)

Does it support IBM 2.88MB drives?

You know, watching all your videos on this channel, I can't help but think "I should port my AX.25 stack to the ZX81". I think that would be a hoot.

Hey, could you share the github repository you made into an .img disk? Btw, excellent tutorial, keep it up!