Search found 2117 matches
- Thu Nov 15, 2018 9:03 am
- Forum: Hardware
- Topic: Vertical Bars on Power Up / Solution
- Replies: 2
- Views: 60
The ZX Spectrum 16k, 48k and Plus models all have a DC/DC converter/inverter power system on the main board to generate +12V and a -5V supply rails for the 4116 DRAM chips. The +12V is also used by the colour encoder chip (LM1889). Models using unmodified issue 1,unmodified issue 2, some issue 3 (un...
- Wed Nov 14, 2018 10:24 am
- Forum: Sinclair Misc
- Topic: Should i move to Europe to acquire a ZX81?
- Replies: 5
- Views: 104
The ZX81 for sale in this thread is priced at £30.95 (plus postage). Using the exchange rate that Google uses gives a price of $40.11 USD (not including postage). Typical prices are around £20 to £40 for ZX81’s that are ‘untested’. Here is a link to eBay.co.uk showing actual selling prices. As you c...
(Glad I could flip the switch without power cycling and re-typing. It was only like a 6 line program, but still. ;-) ) And it looks like my switch worked! Yay! ;-) Yes, the Sinclair ROM code reads the 50/60Hz pin every time it generates a TV line. So if a switch is connected to this pin, you can sw...
- Wed Nov 14, 2018 10:07 am
- Forum: Hardware
- Topic: Why was Sinclair selling UK model ZX81s in the USA?
- Replies: 9
- Views: 475
893B2F76-B2C3-4241-A505-4069DF9B237C.jpeg BAC0334D-255C-4FCA-8A60-7E5FECD9BC8D.jpeg F586C1E8-496B-437F-A42B-C65039B7243C.jpeg BDFBF906-F15C-4507-B27F-28B1E25D4388.jpeg As you can see, the marks show up more on some cases, and on others are rather hard to see unless you catch the light the right way.
Good work on getting your Zeddie working :D :D :D The Sinclair 16k RAM packs are not very reliable these days. The chips used (4116 type 16k bit DRAM types or equivalents) need three supply voltages (+5V, +12V and -5V). Two of these are generated by a simple DC/DC converter/inverter circuit. The ele...
What cell or cells (battery) does your multimeter use? Semiconductor junctions may turn on and conduct when the voltage across them is around 0.6V or higher. There are transistors in the modulator. And in the ULA chip. To carry out continuity testing without the semiconductor junctions messing up th...
Timex Sinclair released TS1510 expansion for TS1500, TS1000 and ZX81, to use ROM cartridges. The Chrome interface has a cartridge port as well. This is compatible with the Spectrum ZX Interface 2. Does anyone know if these cartridge interfaces are compatible? The two different cartridges are comple...