DIY RAM EXPANSION

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tcat
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Re: DIY RAM EXPANSION

Post by tcat »

Toby, Brane, Dave, Mac, ... and All,

Guess what, it works now :D
Measuring all tracks by voltmeter, revealed a loose address line A10, resoldering on the connector side did it.

RAM test after boot really takes a while, slightly longer compared to unexpanded QL.

As I also put TK2 on CARE cartrige EPROM.
PRINT FREE_MEM gives
600064

But this value then slighly varies, after doing some BASIC, DIR, NEW, etc.
e.g. 599552

TCAT


tcat
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Re: DIY RAM EXPANSION

Post by tcat »

Hi All,

I have a new observation, I have seen this code provided by Tobias in another thread pertaining to RAM performance.

Code: Select all

100 ram=RESPR(16): RESTORE 140
110 FOR p=ram TO ram+14 STEP 2: READ x: POKE_W p,x 
125 t=DATE: CALL ram
130 PRINT "Test complete in ";DATE-t;" seconds."
140 DATA 28771,29439,20937,-2,20936,-8,28672,20085
It completes in 17 seconds, not sure, is it actually a good result?

Many thanks so far.
TCAT
Last edited by tcat on Sat May 17, 2014 5:56 pm, edited 1 time in total.


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tofro
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Re: DIY RAM EXPANSION

Post by tofro »

TCAT,

that's about the fastest you can expect for 0 wait state uncontended RAM on the QL (same speed as ROM access) - See here for some comparison figures:
http://www.qlforum.co.uk/viewtopic.php? ... urbo#p6785

Congratulations!
Tobias


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1024MAK
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Re: DIY RAM EXPANSION

Post by 1024MAK »

Well done TCAT Image Image Image

Good to see it is working well :D

Mark


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Dave
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Re: DIY RAM EXPANSION

Post by Dave »

Score!

Congrats.


tcat
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Re: DIY RAM EXPANSION

Post by tcat »

Hi All,

I am sharing back my work as you helped me with it.
It is not perfect, yet functional on my QL.
Soldering is required from both sides, not all pads need to be connected, and there are three vias.
I used therefore straight DIN connector, as this also appears easier to solder with a common non professional iron I have got.
I bent inner connector pins to an angle by tweezers and outer ones left straight, making connections with small lenghts of wire.

Many thanks
Tom
ql512k.zip
GAL Assembly JEDEC DOC files
(2.11 KiB) Downloaded 479 times
ql520-Front.pdf
PCB Front Side
(19.12 KiB) Downloaded 355 times
ql520-Back.pdf
PCB Back Side
(15.8 KiB) Downloaded 313 times
ql520-brd.pdf
PCB Layout & Components
(31.31 KiB) Downloaded 353 times
  • eeschema (2010-03-14)-final >> Creation date: Thu 24 Apr 2014 07:33:24 PM CEST

    #Cmp ( order = Reference )
    | C1 0.33uF
    | C2 0.1uF
    | C3 100uF/10V
    | C4 0.33uF
    | C5 0.33uF
    | IC1 AS6C4008-55PCN
    | IC2 GAL16V8
    | P1 C64AB_FEMALE
    | U1 LM7805
    #End Cmp

    #Cmp ( order = Value )
    | 0.1uF C2
    | 0.33uF C1
    | 0.33uF C4
    | 0.33uF C5
    | 100uF/10V C3
    | AS6C4008-55PCN IC1
    | C64AB_FEMALE P1
    | GAL16V8 IC2
    | LM7805 U1
    #End Cmp

    #End List
Last edited by tcat on Thu May 22, 2014 7:53 pm, edited 1 time in total.


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Dave
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Re: DIY RAM EXPANSION

Post by Dave »

Thanks for publishing this, tcat.

You might want to add your JEDEC for the GAL you used, and a list of parts. This would then be a complete package anyone could put together. Also, by publishing your JEDEC and algorithm people can maybe modify it and feed back into your project.

If people are interested in building this, I have the majority of the parts (not the PCB or DIP version of the RAM though) and if tcat is interested, I'd be happy to put a kit together for those who want to make their own PCBs.


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schombi
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Re: DIY RAM EXPANSION

Post by schombi »

Don´t forget to offer fully populated boards for people that can only replace a capacitor on a Spectrum, like me ;)


Derek_Stewart
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Re: DIY RAM EXPANSION

Post by Derek_Stewart »

Hi,

I was going to make a PCB for myself.

Would there be a demand for more?


Regards,

Derek
Paul
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Re: DIY RAM EXPANSION

Post by Paul »

I guess this depends on when Dave will be able to deliver his RAM, and on your price :mrgreen:


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