Search found 5128 matches
- Sun May 05, 2024 5:34 pm
- Forum: Hardware
- Topic: ZX81 Comp. Mod, no Video
- Replies: 7
- Views: 303
Re: ZX81 Comp. Mod, no Video
Looking at the image from your 'scope, the ZX81 does appear to be working. Some HDMI converters don't like the non-standard video signal from a ZX81, and some LCDs also don't like the signal. But a CRT "vintage" monitor (assuming that it's a 15625Hz "PAL" type) monitor or CRT TV should work okay. An...
- Sun May 05, 2024 1:35 pm
- Forum: Hardware
- Topic: ZX81 Comp. Mod, no Video
- Replies: 7
- Views: 303
Re: ZX81 Comp. Mod, no Video
Here's a screenshot from my 'scope showing the video waveform one of my ZX81 boards showing the output of pin 16 of the ULA (in this case, a 2C210E on an issue one board, this ULA includes the back porch circuitry). For UK and other PAL ZX81 models, note that the output of pin 16 of the ULA also goe...
- Sat May 04, 2024 8:46 pm
- Forum: Hardware
- Topic: Can any ZX80 gurus confirm this statement?
- Replies: 7
- Views: 165
Re: Can any ZX80 gurus confirm this statement?
The photo on the computing history site that you linked to shows two 4K byte EPROMs connected to the ZX80. Although granted, this was a development machine. Given that we know that the ROM code for the later ZX Spectrum was under development even after Sinclair released it (the ZX Spectrum), it is l...
- Sat May 04, 2024 5:33 pm
- Forum: Hardware
- Topic: Can any ZX80 gurus confirm this statement?
- Replies: 7
- Views: 165
Re: Can any ZX80 gurus confirm this statement?
My understanding is that the upgrade kit from Sinclair included a keyboard overlay and a new 8K ROM. What Sinclair called this, I can't say for certain, but my understanding is that it was the same as a ZX81 ROM. If it was not the ZX81 ROM, then can someone please point me to a binary of the special...
- Wed May 01, 2024 10:17 am
- Forum: Hardware
- Topic: ZX81 Comp. Mod, no Video
- Replies: 7
- Views: 303
Re: ZX81 Comp. Mod, no Video
You talk about seeing a composite video signal. What test equipment are you using?
Mark
Mark
- Tue Apr 30, 2024 10:48 am
- Forum: Welcome Area
- Topic: Hello, ZX81 and beyond
- Replies: 3
- Views: 107
Re: Hello, ZX81 and beyond
Hello and welcome to our forum p5s!
I hope you enjoy this forum
The forum is packed with helpful information.
You are welcome to ask questions!
Mark
I hope you enjoy this forum
The forum is packed with helpful information.
You are welcome to ask questions!
Mark
- Mon Apr 29, 2024 7:44 pm
- Forum: Sinclair Misc
- Topic: It seems we are very popular!
- Replies: 3
- Views: 337
Re: It seems we are very popular!
Likely a lot of bots or similar. Some other forums are experiencing something similar...
Mark
Mark
- Mon Apr 29, 2024 7:41 pm
- Forum: Hardware
- Topic: RAM Packs Alternatives?
- Replies: 22
- Views: 626
Re: RAM Packs Alternatives?
Can I assume that all of these should also work with the Timex Sinclair 1000? As a TS1000 is a ZX81 with a differently labelled keyboard, screened case, different modulator and 2K internal RAM instead of 1K, yes, 16K or larger capacity RAM packs for the ZX81 should work fine with a TS1000. Mark
- Sun Apr 28, 2024 11:29 pm
- Forum: Hardware
- Topic: RAM Packs Alternatives?
- Replies: 22
- Views: 626
Re: RAM Packs Alternatives?
Pokemon has in the past made modern RAM packs, but I don't think there are any currently available.
There have also been DIY designs.
Mark
There have also been DIY designs.
Mark
- Sun Apr 28, 2024 6:40 pm
- Forum: Hardware
- Topic: RAM Packs Alternatives?
- Replies: 22
- Views: 626
Re: RAM Packs Alternatives?
As well as the offical Sinclair 16K byte RAM pack, there was the 2K/3K/4K ZX80 RAM pack (memory size depending on how many SRAM chips were fitted in it) that would work with the ZX81. Plus many third party manufacturers that produced various RAM packs. One of the best known for more stable RAM packs...