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Re: 16K RAM Pack photos
Posted: Fri Jun 04, 2021 5:27 pm
by Lardo Boffin
And a Stonechip Panda 16K RAM pack:
Close up of RAM chip:
Re: JRS 16K RAM Pack
Posted: Sat Jun 05, 2021 5:42 am
by bola_dor
1024MAK wrote: ↑Thu Oct 24, 2019 5:19 pm
This is about the sixth design of ZX81 RAM pack that I have seen. Each one uses a different method or different variation of design for obtaining a -5V supply. Some use a transistor oscillator driving an inductor like the Sinclair 16k RAM pack. Some use a CMOS logic chip and capacitors to do it. Some use an audio amplifier chip. IIRC, I think I have seen one using a NE555.
Mark
Microdigital and TK90X-A (Argentinian market versions at least) uses NE555 to make -5v and CZ Spectrum/Plus uses NE555 to make 12v. On the main board as all those are 16KB,
Re: JRS 16K RAM Pack
Posted: Sat Jun 05, 2021 11:43 am
by Lardo Boffin
bola_dor wrote: ↑Sat Jun 05, 2021 5:42 am
1024MAK wrote: ↑Thu Oct 24, 2019 5:19 pm
This is about the sixth design of ZX81 RAM pack that I have seen. Each one uses a different method or different variation of design for obtaining a -5V supply. Some use a transistor oscillator driving an inductor like the Sinclair 16k RAM pack. Some use a CMOS logic chip and capacitors to do it. Some use an audio amplifier chip. IIRC, I think I have seen one using a NE555.
Mark
Microdigital and TK90X-A (Argentinian market versions at least) uses NE555 to make -5v and CZ Spectrum/Plus uses NE555 to make 12v. On the main board as all those are 16KB,
Can you add some photos if you any please?
Re: JRS 16K RAM Pack
Posted: Mon Jun 07, 2021 6:50 pm
by bola_dor
Lardo Boffin wrote: ↑Sat Jun 05, 2021 11:43 am
Can you add some photos if you any please?
Later I ll take some. But I am talking about twhe main board RAM not the packs.. those are 16KB TS1500 clones
Re: 16K RAM Pack photos - please add yours
Posted: Fri Jun 11, 2021 4:28 am
by jsweinrich
I went with a perf board using wire wrap to connect it all. Flat cable from ZX81 edge connector to the perf board. Perf board also has I/O. SRAM is actually 32kx8 (MT5C2568-30).
Re: 16K RAM Pack photos - please add yours
Posted: Fri Jun 11, 2021 3:42 pm
by McKlaud
I did a tiny board with SMD components.
Re: 16K RAM Pack photos - please add yours
Posted: Fri Jun 25, 2021 5:35 am
by bola_dor
This I picked up from the trash. Sold as Czerweny CZ1016, argentina, 99.99% Timex Portugal hardware but note the transistor..
Re: 16K RAM Pack photos - please add yours
Posted: Fri Jun 24, 2022 3:40 pm
by Lardo Boffin
A SPECIAL RAMPACK by Audio Computers:
Although the board suggests it made by Solidisk.
I wonder what goes in the socket?
Re: 16K RAM Pack photos - please add yours
Posted: Fri Jun 24, 2022 5:12 pm
by XavSnap
Re: 16K RAM Pack photos - please add yours
Posted: Fri Jun 24, 2022 10:59 pm
by Lardo Boffin
Interesting! The boards are pretty much identical apart from the green wire from the edge connector being replaced with a resistor and not having the buzzer attached.
I wonder if the buzzer requires the EPROM or just a buzzer to be physically connected?