Sinclair ZX80 / ZX81 / Z88 Forums

That’s the normal “copyright” screen that confirms that it’s the normal ZX Spectrum ROM.

Mark

Is it possible to map RAM in place of the 16K byte ROM? Yes. In fact, the circuitry to do this is not complex. Some versions of the divIDE and the DivMMC can do that. You can then have an all RAM 48K, +, 128K Toastrack or +2 (grey) ZX Spectrum. However, it is not possible to move or map out the scre...

Here’s some photos of one of mine. This particular one having the last known PCB revision (issue 6A): Mark

That's a strange one :shock: All Sinclair made computers had Sinclair on the top left rear of the case. Plus various details as part of the plastic on the bottom. Although Sinclair did not actually manufacture the hardware themselves. In the U.K. Timex did the manufacturing. This ended at some time ...

I still don't see a photo. Use the attachments tab below the edit box to attach a jpeg/jpg image. Note that there is a maximum size limit. Or if using a PC and compatible browser, drag the image file from a folder to the edit box. In both cases, wait for the upload to complete before posting. Mark

Granted, the signal generator in the following simulation is not at all representative of an actual tape input signal, but it gives an idea of what the input circuitry does:

Link to simulation

Mark

Ispy wrote: ↑Mon Sep 16, 2024 2:00 pm Been given this.No badges on it.Is it a real one? Power supply is marked Sinclair but not keyboard.Is it worth anything?Thanks for any help.

You haven't attached a photo...

Mark

netuffgeb wrote: ↑Mon Sep 16, 2024 11:55 am V202 ZX-81_V202.pdf

Apart from the socket, the tape input circuit is the same as Mahjongg‘s design, so they both should perform the same for LOADing.

Mark

The majority of modern TVs (LCD type and some of the later CRT type) require sync signals that comply with the relevant TV/Video standard. In FAST mode, which is used for tape operations (LOAD or SAVE), the correct sync signals are not generated by a ZX80, ZX81 or most clones. Indeed, the ZX81 ULA d...

The LOAD command on ZX80/ZX81 and clones is rather less sophisticated than the ZX Spectrum and clones. These are the possible outcomes (IIRC, I don’t load from tape very often) after you have tried loading from tape or equivalent: The program loads correctly and you either end up returned to BASIC a...