DIY RAM EXPANSION

[tcat]

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

Guess what, it works now
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]

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

[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.theqlforum.com/viewtopic.php? ... urbo#p6785

Congratulations!
Tobias

[1024MAK]

Well done TCAT

Good to see it is working well

Mark

[Dave]

Score!

Congrats.

[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 570 times

ql520-Front.pdf

PCB Front Side

(19.12 KiB) Downloaded 406 times

ql520-Back.pdf

PCB Back Side

(15.8 KiB) Downloaded 380 times

ql520-brd.pdf

PCB Layout & Components

(31.31 KiB) Downloaded 421 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

[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.

[schombi]

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

[Derek_Stewart]

Hi,

I was going to make a PCB for myself.

Would there be a demand for more?

[Paul]

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