Hi gurus.
I think the title says everything. I have a Raspberry 3 and a couple of bad memory packs that I could destroy without remorse, is it possible to build some circuit and use the Raspberry GPIO to load a .p file directly to memory? there's something done?
Thanks in advice!
Question, how do I write to memory through the expansion port? Possible?
Re: Question, how do I write to memory through the expansion port? Possible?
The raspberry Pi uses 3.3v logic rather than 5v so that will be a bit of a problem. Beyond that in theory you could signal the z80 that you need access to the bus via busreq wait for the busack signal then load your program into ram. Then you’ll need to feed the z80 instructions to jump to whatever the rom does after loading a program from tape.
Or something like that.
Or something like that.
Re: Question, how do I write to memory through the expansion port? Possible?
A friend of mine uses the busrq and busack at the moment with the help of an Arduino because of it's 5V bus.
That works good and you can modify ram without problems. So loading software into the ZX81 or other Z80 machines is no problem.
The thing we are developing will become a diagnose module so we can analyze a Zeddy or Speccy without opening it.
To my knowledge there is no loading or saving device existing or under development using the bus.
Kind regards Paul
That works good and you can modify ram without problems. So loading software into the ZX81 or other Z80 machines is no problem.
The thing we are developing will become a diagnose module so we can analyze a Zeddy or Speccy without opening it.
To my knowledge there is no loading or saving device existing or under development using the bus.
Kind regards Paul
In theory, there is no difference between theory and practice. But, in practice, there is.
Re: Question, how do I write to memory through the expansion port? Possible?
Thanks for the responses, guys, I will try Arduino then, I assumed that Raspberry used 5V logic. Where can I find more info on how to do the "charging" of the bytes? I mean the process itself, I know close to nothing about it, Where can I find some specs for the expansion port?? I have searched but no good answers.
Thanks in advice!
Thanks in advice!
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Re: Question, how do I write to memory through the expansion port? Possible?
The details on the expansion connector, more often referred to as the edge connector are here as well as in a lot of other places.
There is a schematic diagram of the circuitry in this post. Although this version has the French video circuitry for the input to the modulator the rest is basically the same for all ZX81, TS1000 and other versions built using the same PCBs.
As for your other question, I’m not quite sure what you are asking.
Mark
There is a schematic diagram of the circuitry in this post. Although this version has the French video circuitry for the input to the modulator the rest is basically the same for all ZX81, TS1000 and other versions built using the same PCBs.
As for your other question, I’m not quite sure what you are asking.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
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Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: Question, how do I write to memory through the expansion port? Possible?
I whant one of that things !!!!Paul wrote: ↑Wed Aug 25, 2021 7:36 am A fried of mine uses the busrq and busack at the moment with the help of an Arduino because of it's 5V bus.
That works good and you can modify ram without problems. So loading software into the ZX81 or other Z80 machines is no problem.
The thing we are developing will become a diagnose module so we can analyze a Zeddy or Speccy without opening it.
To my knowledge there is no loading or saving device existing or under development using the bus.
Kind regards Paul
Are you making it able to scan a rampack attached to it.. that would be usefull...
Ernesto
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come
Re: Question, how do I write to memory through the expansion port? Possible?
If the RAM pack, unlike the Sinclair types, has the edge connector through then our little diagnosis module can be attached behind the RAMpack as long as a Zeddy is first in the Row. It's not designed for it, but will shure work and test the memory for reliability as well as the Rest of the Zeddy
Rampacks on their own will not be tested by our device.
To be honest, I don't use old RAM packs. Once you have a working Zeddy, go for a zxpand (which can't be tested by our diagnosis module) or better a built in memory expansion. SRAM is so much better than DRAM. Or when using DRAM, make shure it's working with 5 Volts only.
The design of Sinclair negative voltage circuits is, how to say, somewhere between optimistic and adventurous.
Rampacks on their own will not be tested by our device.
To be honest, I don't use old RAM packs. Once you have a working Zeddy, go for a zxpand (which can't be tested by our diagnosis module) or better a built in memory expansion. SRAM is so much better than DRAM. Or when using DRAM, make shure it's working with 5 Volts only.
The design of Sinclair negative voltage circuits is, how to say, somewhere between optimistic and adventurous.
In theory, there is no difference between theory and practice. But, in practice, there is.
Re: Question, how do I write to memory through the expansion port? Possible?
I have them all, a ZXspand+, a myself made SRAM module and several Sinclair 4116 based modules..Paul wrote: ↑Wed Aug 25, 2021 7:37 pm If the RAM pack, unlike the Sinclair types, has the edge connector through then our little diagnosis module can be attached behind the RAMpack as long as a Zeddy is first in the Row. It's not designed for it, but will shure work and test the memory for reliability as well as the Rest of the Zeddy
Rampacks on their own will not be tested by our device.
To be honest, I don't use old RAM packs. Once you have a working Zeddy, go for a zxpand (which can't be tested by our diagnosis module) or better a built in memory expansion. SRAM is so much better than DRAM. Or when using DRAM, make shure it's working with 5 Volts only.
The design of Sinclair negative voltage circuits is, how to say, somewhere between optimistic and adventurous.
An edge connector with a rom tester would be interesting but I see is not in your plans.. I am trying to resuscitate some old Sinclair and clones I have..
nothing rational..
Ernesto
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come
ZX80 USA, ZX81UK, ZX Spectrum, ZX Spectrum+, ZX Spectrum 128+ UK, ZX Spectrum +2/A, Sinclair QL, CZ1000, CZ1500, CZ2000, CZ1000Plus, CZ1500Plus, CZ Spectrum, CZ Spectrum Plus, TK83, TK85, TK90X, TK95. TS2068. And more to come