Re: Transwarp GS ROM 01 vs ROM 03

[Mitchell Spector <mitch2gs@hotmail.com>]

"Rusty" <rdekema@gmail.com> wrote:

>Greetings,
>
>Do any of you know why a Transwarp GS might work in a ROM 01 GS but
>not in a ROM 03 GS?

    No. However, I think it's a case of a damaged/weakened CPU 
socket, the fact that it's a ROM 3 revision motherboard is probably 
not a variable here.

>I ask because my recently-repaired TWGS (v1.5) does exactly this. It
>works perfectly, passes all self-tests (both the TWGS and IIGS self
>tests), and results in a stable system on my ROM 01 GS, but does not
>work at all on my ROM 03 GS. When I power it up in the ROM 03 unit,
>the computer acts like there is no CPU installed at all - I just get
>the black and white checkerboard pattern on the monitor, and the green
>LED on the TWGS does not light up.

    Typically, in my experience, that means either the oscillator is bad
(or not installed) or the CPU socket isn't making proper contact with 
ribbon cable's pins.

    From what I remember the ribbon cable has thicker pins and longer 
than the standard 40-pin DIP 65C816. When installed, it pushes the 
internal pin contacts on the motheboard outwards. If you continously
remove and re-insert a CPU ribbon cable you end up weakening and 
bending the pins to the point there's no longer proper contact. This 
leads to either unstable performance(?) or what appears to be a 
dead card.

    I'm fairly sure this is the reason my 15/64 Zip GS won't run 
stable on my ROM 3, yet worked fine in another person's machine.
(I really need to find a replacement board with a virgin CPU socket; 
anyone have a spare?). :)

>The ROM 03 IIGS works perfectly well using the stock processor (is
>stable, passes the self-tests, etc).

    The stock processor will typically work fine in a board where
the pins have been damaged.

>It's not a big deal by any means and I am mainly just thrilled to
>finally have a working accelerator. But if I could easily change
>something to make it work in the ROM 03 GS, I'd prefer to do so.
>
>Henry from GSE-Reactive mentioned a couple of configuration bowties
>that might need to be opened (cut) on the TWGS card, but he said he
>was not familiar with this exact situation and recommended asking
>here.

    I'd be surprised if it were the card itself, it would be the first I've
heard of a TransWarp GS not working in a ROM 3 board. At any
rate my best guess would be the CPU socket.

Mitchell Spector