[vcf-midatlantic] ZX81/TS1000 with a modern TV

Glenn Roberts glenn.f.roberts at gmail.com
Mon May 23 22:26:37 UTC 2022

I have no experience with Sinclair but didn’t they have a built-in RF modulator? That would put out an old style UHF or VHF signal that a modern digital TV can’t decode. I believe you’d need an older TV to test these…

Sent from my iPad

> On May 23, 2022, at 5:54 PM, Dean Notarnicola via vcf-midatlantic <vcf-midatlantic at lists.vcfed.org> wrote:
> I’ve read that the ULA on some older TS and ZX units do not put out a 100%
> proper NTSC signal, something do with the contrast. It may be that modern
> TVs have issues, but CRT tuners can deal with it. Considering they are all
> demonstrating the same behavior, these units may be fine.
>> On Mon, May 23, 2022 at 4:32 PM Jeff S via vcf-midatlantic <
>> vcf-midatlantic at lists.vcfed.org> wrote:
>> The K cursor is normal, and standard. The ZX81 does not have any kind of
>> intro or status boot screen. If you're seeing the K, then unless there's
>> something wrong with the keyboard, you should be able to see any numbers
>> you type.
>> On Mon, May 23, 2022, 4:21 PM Bob Shuster via vcf-midatlantic <
>> vcf-midatlantic at lists.vcfed.org> wrote:
>>> So I have two (2) Sinclair ZX81s (US version - one is still an unbuilt
>>> kit), and three (3) Timex-Sinclair 1000s.  I’ve connected them to a TV
>>> using an RCA-coax adapter and tuned to the correct channel, but I get a
>>> grey screen with the “K” cursor visible.  I’m unable to get past this.
>>> This is for all four units.  They seem to tune in white momentarily then
>>> switch to fuzzy grey - with the “K” still visible.  This was both on a
>>> large 4K OLED set and a small HD LED TV, and I suspect they are just too
>>> new to deal with the monochrome signal.  I don’t have a CRT TV to test
>>> with, just old monitors (which of course don’t have antenna connections.)
>>> Any advice?  I’m selling these, so I’m not getting into modding them,
>> just
>>> want to confirm they’re working properly.
>>> Bob Shuster

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