Upgrading an 030/25 mhz accelerator

[Miked]

If you increase the speed of a 030 accelerator, do you need to use faster memory?  For example, if you are using a derringer 030/25 which is using a certain speed SIMM (e.g. 80ns); if I were to modify the card by replacing the oscillator and adding a 50 mhz 030, do I need to change the SIMM memory to 60 or even 50ns Ram?

-Miked

[DamageX]

If the accelerator was designed to run at only one speed (25MHz) then you'd be lucky to get it running at 50MHz even with the faster CPU and RAM. If it was designed to run at multiple speeds and/or has jumpers concerning memory timing then that would be more promising.

Since 60ns SIMMs are relatively easy to find and easy to exchange you might as well put those in first and then try to get the CPU running as fast as possible with memory latency as low as possible.

[Miked]

Well, there was a Derringer that ran at 50mhz.  But aside from that, my real concern is the ram speed.  Did these accelerators take fpm memory or edo memory, parity or nonparity?  Or does it not matter?  

Additionally, searches for 40ns/50ns 32MB 72pin SIMMS have been unsuccessful.  Can it run at 50mhz with 60ns Ram?

Anyone have a 50mhz Derringer?

-Miked

[Ilwrath]

I agree with DamageX.  You can't just change the crystal and CPU to double the speed of the card.  The rest of the logic components on the card won't be able to take that type of timing.  

IF (and that seems unlikely) the 50mhz board unit contains all the same components and layout as the 25mhz board unit, there is probably a jumper/trace difference that halves the clock rate for the rest of the components (or sends the half-refresh signal to the CPU, thus doubling it).

In other words, running a 2x multiplier 25mhz clock for the 50mhz version vs. a normal 1x multiplier 25mhz clock on the 25mhz model.

[Miked]

Ilwrath wrote:

In other words, running a 2x multiplier 25mhz clock for the 50mhz version vs. a normal 1x multiplier 25mhz clock on the 25mhz model.

Interesting.  So, the speed of the ram really isn't that much of a concern?  Assuming it did work (doubling the clock speed) what would be the implications of using the same speed ram that ran in the 25mhz version?

-Miked

[KThunder]

ram speed is a concern. if the system normally is running with no wait states with 70 nanosecond ram and you speed it up it will have to wait for the ram thereby nullifying the speedup. 50 nanosecond ram may allow it to run faster.

if the support chips and cpu can stand 50mhz and the sysem doesnt have 60 or even 50 nsec ram get it it will probably give you another 5 to 10% in speed.

[DamageX]

I guarantee there are waitstates, the question is how many. If I understand correctly, an '030 could complete a memory access in 2 cycles, or a 4-word "burst" in 5 cycles. But if you're over 16MHz then even 60ns DRAM is already too slow for that ideal timing.

A GVP A3001 with '030-50MHz, 60ns RAM, and no burst mode, is 85% faster than a CBM A2630 with '030-25MHz, 100ns RAM, and no burst mode.

[Brian]

The Deringer is made to go 50Mhz but you need to get hold of a 100Mhz crystal to get there, as far as I know the components are the same for 16, 25, 33, 40 and 50Mhz 030. There's a jumper for 25 or 50Mhz FPU but no jumpers for the CPU speed. EDO memory an be used but theres no speed benefit over FastPage memory.

[HyAmi]

I've got a Derringer card (@25MHZ) and I also wanted to change it to 50MHz. Someone at ebay put up two Derringers for sale at the time; 25 and 50MHz. I asked this person if there were any differences beside the oscillator. He compared he cards and answered that there were some parts different (can't remember which) but the 50MHz version did have better (read: made for higher clock frequencies) parts.

In the end, I didn't try it at all. The risk of frying a card like this... Maybe a little overclocking. But if I'm just too carefull, please tell me what's possible!

[Miked]

HyAmi wrote:
Derringers for sale at the time; 25 and 50MHz. I asked this person if there were any differences beside the oscillator. He compared he cards and answered that there were some parts different (can't remember which) but the 50MHz version did have better (read: made for higher clock frequencies) parts.

In the end, I didn't try it at all. The risk of frying a card like this... Maybe a little overclocking. But if I'm just too carefull, please tell me what's possible!

Hmm, I wonder if there is a current-voltage difference between the 2 cards.  (Id be curious to know if any resistors are different).

I just spoke to someone who has clocked his 25mhz derringer at 33mhz.  He simply put in a 66mhz oscillator in the card and changed the 25mhz 030 to a 33mhz one.  So, at the very least, an 8mhz gain can be had.  (whats the speed increase? 24%?)

I still say its worth a try to drop in a 030/50 and get a 100mhz crystal and some 50ns (or faster) ram and see what happens.  

-Miked

/Edit
 I suppose since there is electrical oscillation that the capacitors might be different as well (25mhz vs 50mhz card).