A500 rom problem

[jvdbossc]

I posted this

https://www.amibay.com/showthread.php?t=4188 some time ago,

after modding a pc floppy

https://www.amibay.com/showthread.php?t=4208

I am finally able to testdrive the A500(+)

There is a strange problem: with the 1.3 rom it is unstable unstable, without the hd and with the hd not tested!

When i put in the original rom from commodore 2.XX in the rom switcher the machines stays running over night, the same with the 3.1 rom but not with the 1.3 rom.

did mail amigamaniac, and admitted the 1.3 rom was dropped for 1,5 meters (not wanting to bother supportive hardware creators with abuse)

So has anybody an idea? Could it be caused by dropping? It is a TC574200d-120

 

[desiv]

Not a board level chip guy really, but...

I suppose it's "possible", but I don't see how dropping a ROM chip would damage it from that height..

Unless you dropped it onto metal screen that had just been rubbed with a lot of balloons..
(Well, you get my point...)

I've dropped a lot of game carts from 5 or 6 feet in height and it's never caused a problem, and they are (mostly) just roms on boards.
(Now, it's not for fun.. I just tend to stack them on a filing cabinet, and then knock them over.. It's a mess issue.)

desiv

 

[jvdbossc]

indeed

indeed

just hoping one of the amiga tech guru's will pick up this message and give a reason/solution.

Indeed dropping it should not be a problem, however it is a programmable "light" chip so wondering if it could be damaged.

I would be happy if it would work with any 1.X rom so I can put that in.

Did receive software for that A500 2.X, but wan't to run mine. Like lotus turbo challange etc (nostalgia)

Know that on the A600 it was incompatible with lots of disks

 

[rkauer]

Possible reason: the 1.3 ROM is not fast enough. They commonly are in the 150~200ns area. Newer Amiga ROM must be 120ns or even less.

 

[TheCorfiot]

I agree with my good friend rkauer,
Can you take a close up pic of the Eprom (with no label of course) or read the speed designation off the text imprinted on the chip

TC

 

[jvdbossc]

exact text pic later

exact text pic later

txs for help

it says:

toshiba tc574200D-120
vpp 12-5V 0644
1999 MX1C

 

[fiat1100d]

txs for help

it says:

toshiba tc574200D-120
vpp 12-5V 0644
1999 MX1C

Should be 120ns so sufficiently fast!

 

[rkauer]

Other than the ROM is some way busted, I can't recall anything more wrong.

The A500+ must work correctly with an ancient 1.3 ROM version.

 

[jvdbossc]

ok txs

ok txs

had contact with the seller and tells me, or I order another one from him, but he recommends to look for the original since the roms are more fragile and error prone he says, well will do this, still have to find some boxes with spares who do not wan't to be found.