yves@vache.CAM.ORG (Yves Laurin) (06/04/90)
but how do you generate this signal -- nobody is perfect and i'm the living proof of that yves laurin
c8748411@cc.nu.oz (06/07/90)
I have just read (in comp.sys.amiga.tech) a reference made to piggy-backing RAM chips. What the hell (excuse the french) is RAM chip piggy-backing. I only ask because a fellow student asked me, well, just this very morning, if it could be done as a mate of his told him it could. I said it couldn't. HELP! Am I fool? Quick, someone cast the light of tricky-Amiga-know -how to me (just a ray would be enough) and enlighten me! Yours embarrassingly humble, The GAMMA Play
John.Matthews@comp.vuw.ac.nz (John Matthews) (06/08/90)
A long time ago, there was apparently an article in an early Amazing Computing, giving instructions on how to piggy back (a number of) ram chips on the chips on the Amiga 1000's motherboard, thus boosting its memory from 512K to 1Meg. There is reference to this in the Rejuvenator's installation instructions, as the pile of chips makes it difficult to install the Rejuvenator. Don't know if the hack is possible on other Amigas though.
geoff@actrix.co.nz (Geoff McCaughan) (06/08/90)
In article <2113.266ea123@cc.nu.oz> c8748411@cc.nu.oz writes: > > I have just read (in comp.sys.amiga.tech) a reference made >to piggy-backing RAM chips. > > What the hell (excuse the french) is RAM chip piggy-backing. You can piggyback RAM in an A500 or A501. RAM on the A500 M/B is addressed by DRA8:0, _CASL/_CASU and _RAS0/_RAS1, all except the latter being in effect in parallel. The _RAS signals select which 512K bank is being addressed. You could add 512K to a 512K A500 by piggybacking RAM chips pin for pin, but leaving pin 4 bent out. Wire all the pin 4's (_RAS) together and connect to _RAS1. You also need to ground the EXRAM line for this to work. Still no clock though 8-(. You can upgrade an A501 to 1M by doing the same thing, but you need a hardware hack to generate a _RAS2 signal 1st. Doing this to an A501 is a class A bitch, you need a fine soldering iron, good light and a steady hand. Getting the shielding back on afterwards is tricky too. If you try this _PLEASE_ check three times before applying power, make sure all your chips are the right way around and that you haven't splattered solder anywhere. The writer takes no responsibility for any smoked Amigas which may result from this. Note the info above pertains to the rev. 5 A500 which uses 256x1 chips. rev. 6 boards have 256x4 chips and room for an extra 512K on the M/B. Happy hacking! ------------------------------------------------------------------------------- Geoff McCaughan Email: geoff@actrix.co.nz Phone: +64 3 539545 or 852101 Amiga/Hardware/Unix/Quantum Mechanics Hacker Phax : +64 3 539567 "Anarchy: Think of it as evolution in action." ^ NEW ZEALAND!
peterk@cbmger.UUCP (Peter Kittel GERMANY) (06/08/90)
In article <2113.266ea123@cc.nu.oz> c8748411@cc.nu.oz writes: > What the hell (excuse the french) is RAM chip piggy-backing. > Well, this is an absolutely OBSOLETE (but standard for Atari ST) method to expand your RAM capacity to the double. On top of each existing RAM chip you solder another one, pin for pin, only letting the Select pin (CAS) of each free. The latter ones are connected together and must lead to "some circuitry" that does the address selection. Not recommended by Commodore, absolutely not. -- Best regards, Dr. Peter Kittel E-Mail to Commodore Frankfurt, Germany rutgers!cbmvax!cbmbsw!cbmger!peterk
bleys@tronsbox.UUCP (Bill Cavanaugh) (06/09/90)
I think what he meant was exactly what he said: "What ... is piggybacking?" It's connecting one chip to another in parallel, pin for pin. You usually put one pin on top of another, thus the name... /******************************************************************** * All of the above copyright by the below. * * * * Bill Cavanaugh uunet!tronsbox!bleys * * * * "You can only be young once, but you can be immature forever." * * Larry Anderson * ********************************************************************/
kim@uts.amdahl.com (Kim DeVaughn) (06/10/90)
In article <267062a0-6a9.3comp.sys.amiga.tech-1@tronsbox.UUCP>, bleys@tronsbox.UUCP (Bill Cavanaugh) writes: > I think what he meant was exactly what he said: "What ... is piggybacking?" > > It's connecting one chip to another in parallel, pin for pin. You usually > put one pin on top of another, thus the name... Except for one or more high-order bit address pins, which you have to wire to the appropriate address line(s) on the bus. /kim -- UUCP: kim@amdahl.amdahl.com or: {sun,decwrl,hplabs,pyramid,uunet,oliveb,ames}!amdahl!kim DDD: 408-746-8462 USPS: Amdahl Corp. M/S 249, 1250 E. Arques Av, Sunnyvale, CA 94086 BIX: kdevaughn GEnie: K.DEVAUGHN CIS: 76535,25
frix@hexagon.pkmab.se (Fredrik Rothamel) (06/11/90)
>You can upgrade an A501 to 1M by doing the same thing, but you need a >hardware hack to generate a _RAS2 signal 1st. Can anyone please tell me: 1. How do I perform this hardware hack ? 2. Can I expand my amiga to more than 1.5Meg ? (.5 + "hacked" A501) -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- ! Fredrik Rothamel, Syrenvaegen 9, S-702 20 OEREBRO, Sweden ! ! Internet: frix@hexagon.pkmab.se ! ! UUCP: sunic!kullmar!pkmab!hexagon!frix ! -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-