ExtRAM 512kB to 640kB for CPC6128 on One DIP20 chip SLG46533v-DIP

[McArti0]

Ext. RAM 512kB to 640kB for CPC6128 on One DIP20 chip SLG46533v-DIP, one resistor and ... 6 diodes.

[McArti0]

Starring 50pin SCSI As Mx4 

SymbOS in CPC6640

[Prodatron]

Wow, that looks so great! Congratulation, McArti0!
TBH I have never seen a 640KB CPC system before.

I think 640K is enough for everyone.

[Bryce]

Great design. I like the use of diode logic, keep it retro!

Bryce.

[McArti0]

I think 640K is enough for everyone.

 
And it's not a quote because apparently Billy didn't say it.

[McArti0]

Great design. I like the use of diode logic, keep it retro!

Bryce.

Seriously though, this is panic saving pins.
Due to the fact that MREQ did not reach the IC, therefore RAMDIS is also sent during IORQ. 
This could be a problem later.
Moreover, the diode and resistor cause a large delay of one of the pulse edges.
Circuit will not be suitable for fast 16/20MHz CPU.

[Bryce]

Great design. I like the use of diode logic, keep it retro!

Bryce.

Seriously though, this is panic saving pins.
Due to the fact that MREQ did not reach the IC, therefore RAMDIS is also sent during IORQ.
This could be a problem later.
Moreover, the diode and resistor cause a large delay of one of the pulse edges.
Circuit will not be suitable for fast 16/20MHz CPU.

Try adding a 10pf capacitor in parallel with the diode (or resistor). That will allow the leading edge to rise faster.

Bryce.

[GUNHED]

Wow, that looks so great! Congratulation, McArti0!
TBH I have never seen a 640KB CPC system before.

I think 640K is enough for everyone.

Yeah, Bill Gates told that already decades ago! 

BTW: Take a look at Tot0's X-MEM, it does also provides 640 KB RAM on the CPC6128. This was released also a decade ago. 

[Brocky]

Wow, that looks so great! Congratulation, McArti0!
TBH I have never seen a 640KB CPC system before.
I think 640K is enough for everyone.

Yeah, Bill Gates told that already decades ago! 
BTW: Take a look at Tot0's X-MEM, it does also provides 640 KB RAM on the CPC6128. This was released also a decade ago. 

ive been hittin 640kb in symbos with 512k ram expansion and onboard ram..

[Bryce]

Wow, that looks so great! Congratulation, McArti0!
TBH I have never seen a 640KB CPC system before.

I think 640K is enough for everyone.

Yeah, Bill Gates told that already decades ago! 

BTW: Take a look at Tot0's X-MEM, it does also provides 640 KB RAM on the CPC6128. This was released also a decade ago. 

Yeah, except Bill never actually said that. It's a fake quote that somehow refuses to die.

Bryce.

[Gryzor]

[Egg Master]

Wow, that looks so great! Congratulation, McArti0!
TBH I have never seen a 640KB CPC system before.

I think 640K is enough for everyone.

Yes. 640K ought to be enough for everyone.
I'm using the xmem, and it allows that too.