Project Blizzard Turbo Memory in my A600

[Photon]

Discovered another Boxed Beauty (tm) in a box'o'goodies. Had forgotten I bought this, as usual




14 MHz 68000 and up to 8 MB fastram... YeAhH!!


I just ordered a 68000 PLCC socket (and TONS of stuff) from Futurlec, and the board even has two sockets on the solderside:




So, hm... this is a pretty big beast. A quick test suggests it would barely fit "under the ventilation grille". It's about the size of the floppy drive (which is replaced with a floppy terminator ) but not as "thick".

Could I solder some flatcable to the PLCC socket, split up the cable into cablelets where necessary, and solder on the DIL socket?
I'd use slightly thicker separate wires for Vcc/GND and add antinoise caps if necessary, but:

Some follow-up questions arise:
- Would it be sensitive to noise this way?
- Any other drawbacks?
- Would you do it another way? Then tell me!

[rkauer]

Probably occasional Mr Guru visits from time to time due the length of the cable.

Also use one more rounded pin 68000 socket to avoid destroying the one in the accelerator if the hack don't work.

[EDIT] Don't forget to use the install disk found in Installer's Heaven!

[Zetr0]

@Photon

With the help from Narmi and some guys over at Amiga.org (and our dear rkauer)

I designed this





originally posted in this thread

http://eab.abime.net/showthread.php?...A600cpc&page=2

I will say there is a subtle error in the design:-

The 74LS00N is used to hand-shake and grant access to the other CPU on the bus and place the other CPU in halt is wrong. I am missing 2 lines

it should look like this


I cannot remember if i revised the original schematic but it would't take long to do to be honest =)

If you want to have a play, you can download the eagle board from here

[Photon]

A big thank you for the answers guys

Zetr0: that's to keep the original 68000 quiet / from wanting to access the buses, I guess?

I have some fingerboards here, I think I'll add a small one to the socket, if it's the right pin distance.

If not, where can I get the board made? I don't mind adjusting for the 2 lines you forgot.

Originally Posted by rkauer

Probably occasional Mr Guru visits from time to time due the length of the cable.

Also use one more rounded pin 68000 socket to avoid destroying the one in the accelerator if the hack don't work.

[EDIT] Don't forget to use the install disk found in Installer's Heaven!

I do have a flatcable solution in my A500-040 (hand-soldered, to work around the problem of triple machined 68000 sockets on top of another!!) and it never gurus.

But I'll take your advice. Can I improve things with "every other flatcable wire is GND"? The cable length will be about 12-13cm I guess.

And did you see that the board already had a second (removable) 68000 socket? (I do have 68000 sockets tho, that's not the problem.)

[Zetr0]

@Photon

my friend, if you are running cables, try keep it shorter than 7cm on each line, double up on the ground and voltage lines.

I tried building a CPU extender for my A2000 Rev4.5 board, alas at 8cm's (each wire) it drove the CPU line driver to hard, and I believe killed a CIA.

DDNI's kindly offered me some a500 chips so I may yet get that board up and running.

If you drive the CPU lines to hard (hence to far) you are likely to kill a CIA in the A600.

---- Redesigning the A600CPC

when re-designing the eagle board, add about 15mm to the distence of the CPU DIP socket and PLCC Socket this should give you better clearance with the blizzard, do mind the Keyboard connector though.

to get this built you could look at www.futurlec.com, just keep your trackwidths no lower than 10mils and track spaces no lower than 8mils

[Photon]

Hm, considering this quite big hunk of electronics again... I like Frankensteining, but looks like it could eat a lot of power and make the portable rather heavy.

Since I have to do a board anyway, is there some simple design made for a fastram expansion a la those in sidecar expansions, that is compatible with say a 72-pin or a 30-pin tiny SIMM module?

I could mod it if it's made for Zorro or other cpu socket.

[Shadowfire]

Originally Posted by Zetr0

@Photon

my friend, if you are running cables, try keep it shorter than 7cm on each line, double up on the ground and voltage lines.

I tried building a CPU extender for my A2000 Rev4.5 board, alas at 8cm's (each wire) it drove the CPU line driver to hard, and I believe killed a CIA.

Youch. Sounds like the impedance mismatches caused some pretty harsh signal reflections.

[Photon]

Yeah, my PPS040 is special, as in designed a bit unlike other accels, Ie. the piggyback is just a through connection and you plug the original CPU in a socket next to the thrusocket on the accel board.

So my flatcable would simply be a simple short physical connection, shorter than 7cm btw. If the PPS040 does any buffering or such between the "68000 mobo socket" and the "onboard socket with a 68000 in it" is unknown.

Anyway, due to recent events (doesn't that sound secretive now! ), I've abandoned this mod. I've restored an A500 PSU tonight + tested an A500+ to plug it into tomorrow

I try to keep it less than 5cm just to be on the safe side when running cables.

satellite direct | forex automoney

[Photon]

Turbomem is sold to an A500 friend in need, my A600 got an A6055 card and now an ACA630 so...