QL-SD card project

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Simon_Carr
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Re: QL-SD card project

Post by Simon_Carr »

Hear Hear! Having been away a lot recently, I've just got back to see lots of posts elsewhere in this forum regarding costs of gold cards etc...

I'm not posting to that discussion, because it seems to have become completely and unnecessarily nasty, but I think the discussion does really highlight the need, and market for an SD card based storage system. I really hope that something does come of this, because clearly this issue is going to become all the more pressing. The QL needs an SD card, RAM boost and perhaps also improved/enhanced ROM facilities.

Oh and a convertor to be able to use an Atari joystick would be nice, and much easier to deliver!


Unpacking a JS-ROM QL, with a QL-SD and SuperQBoard, and busily refelting millions of microdrives
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Dave
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Re: QL-SD card project

Post by Dave »

As always, I'm here ready, willing and able to manufacture anything that is a finished design, and sell it at a low price.


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1024MAK
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Re: QL-SD card project

Post by 1024MAK »

So, there I was thinking... Does anyone know of a finished *working* design for a time machine for Dave to err, manufacture? :mrgreen:

Seriously, thanks for your support Dave :D

And in-between the err, debate that is being refered to, the relevent bit about SD cards is here:
1024MAK wrote:If the QL community wants to survive, new active members are needed (see the problems with QUANTA and QL Today). Microdrives are not viable long term. Floppy disks are not viable long term. Emulation is not the answer either (explain to me how I can encourage a young person to use an emulator of an obscure {to them} old 1980's computer on an all singing, all dancing modern computer).

So an SD card system is vital. Also important is an inexpensive RAM card (with a socket for a EPROM/EEPROM/Flash chip so that people can have access to the extra commands in Toolkit).

Myself, I would also like an expansion card with all this included that slots into the expansion port.

The increasing cost of living that is affecting vast numbers of ordinary people is going to affect people around the world for many, many more years. So keeping the cost of new hardware low or at a reasonable price is important.
Mark


:!: 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 in Somerset later in the year :)

QL, Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (Sinclair and Acorn)(nearly forgot the Psion's)
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Dave
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Re: QL-SD card project

Post by Dave »

My gut instinct is that we should throw up a Kickstarter campaign to raise some funds to a) properly reward the first to market for their work by paying some or all of their development costs and b) using the remainder (if any) to offset production costs with the condition this be passed through to the consumer.


Simon_Carr
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Re: QL-SD card project

Post by Simon_Carr »

Good idea, although I don't know how big the QL community is, so would suggest a fairly low target to raise. I would certainly back it with my spare cash if it was to help such an item come to fruition.


Unpacking a JS-ROM QL, with a QL-SD and SuperQBoard, and busily refelting millions of microdrives
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Peter
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Re: QL-SD card project

Post by Peter »

This picture shows the ROMOE signal on my SuperGoldCard QL, which is used as an imput to QL-SD. The horizontal dotted line is the maximum allowed low level TTL voltage of 0.8V. The measured signal illegally goes up to 1.5V where logic level is low. The oscilloscope has a bandwidth of 60 MHz only, so the spikes visible to a >300 MHz PLD might be higher.
SGC_romoe_large.JPG
SGC_romoe_large.JPG (22.89 KiB) Viewed 5264 times
The 30 year old circuitry of the QL was too slow to see this, so the fault did not have immediate effects. But the QL-SD uses a contemporary PLD, with over 300 MHz maximum operating frequency, which considers it a valid ROMOE signal and does unexpected things. Other signals than ROMOE are also far from perfect.

Quality of ROMOE is better on a standard QL.


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1024MAK
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Re: QL-SD card project

Post by 1024MAK »

Best get some 220Ω resistors and 47pF capacitors then to low pass the filtor the signal...
Follow that with a schmitt trigger input and plug and pray :P

Yes, I know, it's never that simple :-(

Mark


:!: 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 in Somerset later in the year :)

QL, Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (Sinclair and Acorn)(nearly forgot the Psion's)
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Peter
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Re: QL-SD card project

Post by Peter »

1024MAK wrote: Yes, I know, it's never that simple :-(
Mark
And here's one of the examples why: Noisy low-level address signal at 1.2V during ROMOE active-high. (Scope has persistance on, address signal on top.) To deal with this kind of noise, the adress line is sampled at ROMOE rising edge, where there is less noise. Now if ROMOE is delayed by filtering, the adress line might get evaluated at the worst moment.
GC_addr_romoe.JPG
GC_addr_romoe.JPG (27.49 KiB) Viewed 5249 times
In the next step you'd filter every address line. ;) I was posting this because Dave asked for details, and also as a warning what needs to considered when using modern PLDs. I do not lack ideas what could be tried, but the design is finished & well tested on the standard QL, so I won't rip up the whole thing again. I have already invested far more time than reasonable. And Adrian Ives as well.


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1024MAK
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Re: QL-SD card project

Post by 1024MAK »

Yes, with digital signals, correct timing is everything.

A question. Could some of the problems be due to a poor ground layout / tracks? Are you seeing a form of "ground bounce" where the voltage drop through the ground is helping to cause the voltage on the signal lines to be out of spec?

Mark


:!: 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 in Somerset later in the year :)

QL, Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (Sinclair and Acorn)(nearly forgot the Psion's)
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1024MAK
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Joined: Sun Dec 11, 2011 1:16 am
Location: Looking forward to summer in Somerset, UK...

Re: QL-SD card project

Post by 1024MAK »

Thinking about my comments after hitting the post button, if the 'scope is grounded at a good "solid" ground point, probably not ground bounce :oops:

Mark


:!: 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 in Somerset later in the year :)

QL, Falcon, Atari 520STFM, Atari 1040STE, more PC's than I care to count and an assortment of 8 bit micros (Sinclair and Acorn)(nearly forgot the Psion's)
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