Memotech HRG ROM/PAL dumps?

[1024MAK]

Do you mean the Memotech HRG or the chips?

Lets put it this way, the Memotech HRG don’t come up very often.

The PALs are obsolete. But can be replaced by GALs, but I suspect you already know this.

Mark

[XavSnap]

OMG destroy a Memotech to understand this mysterious card ?

Don't do that, it's bad luck for at least 81 years.

[Paul]

OMG destroy a Memotech to understand this mysterious card ?

Don't do that, it's bad luck for at least 81 years.

Maybe I should do so.
That could ensure me get at least 141 years old

[system11]

Well hopefully not destroy. Desoldering these is pretty easy with a proper vacuum driven desoldering station - I've pulled hundreds of chips at this point. The reading/etc is not a risk. It's the overall "subjecting old parts to more heat than they're used to" thing. It's definitely working at the moment.

[GrantmeStrength]

I have a HRG pack, but it doesn't seem to work - the first example in the manual that's supposed to be a "quick test" makes the screen blank and then return with a weird */0 error, which is a first for me.

I removed the EPROM to test it, and it's fine (so I put it back).

I guess it's possible the PAL's are broken, but I don't know how to test that or replace them

[Moggy]

Used with a ram-pack and a 1200 milliamp power supply as recommended by Memotech ?

Manual can be found here...

https://zx81stuff.org.uk/zx81/hardware/ ... .00.27.jpg

[GrantmeStrength]

Yes:
Memotech 16K ram pack (jumper 1 down, 2 up, 3 up, 4 down).
Memotech HGR park with jumper in
9v, 2A PSU

Entering:

LET V=19000
RAND USER 8619

blinks and returns 0/0

[Moggy]

It's been a while since I used mine but will dig it and a Memotech 16k pack out and give it a run through to see if I can find a solution.

A quick question. Does the Zeddy boot up with nothing attached? I only ask as the the HRG pack relies on the Zeddy's internal memory to function and if that's borked then that could be the problem, also what is this jumper you mention?

[XavSnap]

Hi,
Yes you had to set the 16k Memotech as a "MASTER" card, and place it before the HRG. ( or "Slave" after ??? can't find the 16k RAMPACK Doc.)

As shown in the 161:32/64k RAM PACK Manual, the A10 adresse line is drive by this card.


http://zx81.ordi5.free.fr/memotech/MT06_HRG/
Can't locate the famous jumper, only the push button to reset the BASIC display...

[GrantmeStrength]

Yes, the ZX81 works great without the RAM pack, and with it.
I've tried placing the cards in the sequence:

ZX81 -> 16Kb -> HGR
ZX81 -> HGR -> 16Kb

and there is no difference. Returns immediately with 0/0 after a brief flicker.