Hardware Wanted

ACA57 Gemini II, IBM 5x86 @ 100MHz, and its brochure


hi
I am planning to use the Gemini II interface under !PC/v308 (I got sources) , under RiscOS v4.39 , I have recycled a CDROM chassis to accomodate an MC68332 inside, I have attached a BDM cable to the MC68332 board , and the other side to the parallel port of the RiscPC , the BDM control program is a DOS application , DOS v6.22 runs good, and SierraC/68K (professional C compiler for 68k) will work greatly good with a 586 CPU . Currently I have a poor 486 SX40 . I am expecting a boost of fun from the 586 , I already get ready to wave, so …


… so, If you have one of these, let me know, thanks

I was going to point you to this one but the auction finished earlier today (and probably more than
http://offer.ebay.co.uk/ws/eBayISAPI.dl ... 7675.l2565

BUT there's also this one ... http://offer.ebay.co.uk/ws/eBayISAPI.dl ... 7675.l2565

Does it have to be a 5x86? I think you'd mentioned having a 486DX4/100, and the performance difference is not that great (unless you find a 5x86 with 512KB cache rather than 128KB, but even then things like having a StrongARM rather than ARM710 make a bigger difference).

I suggest you try comp.sys.acorn.hardware - probably a few people with unused PC cards, though I suspect mostly 486s.

ajw99uk wrote: I was going to point you to this one but the auction finished earlier today

yeap, too late, there is an other auction but that dude is asking too much (~180 Euro)

ajw99uk wrote: I think you'd mentioned having a 486DX4/100

I had a DX4 , then a swapped for a 486SX , which is slower, btw when I swapped I was planning to upgrade to 5x86 , and as for money difference I also got a pair of great chips, SPI-UART chips . So I swapped 486DX4 , for a 486SX + marvelous chips.

These SPI-UART chips plus their crystals (you need the right value) are good if you want to add a debug interface to an Hacked PDA based on EZ328 . I swapped also because … unfortunately I can't find any ucsimm/328 around, and these chips are hardly to be found.

ajw99uk wrote: the performance difference is not that great (unless you find a 5x86 with 512KB cache rather than 128KB

486-DX4@100Mhz against 586@100Mhz … umm good match … about the DOS software that has to run under !PC/Pro , I think the 586 should be improved by all the improvements made with the internal architecture, the faster bus, which is 64bit instead of 32bit, but I do not think the gemini II chip has any benefits because the interface is 32bit, but ... a 586 has the burst mode, so in short I am expecting a speedup.

ajw99uk wrote: but even then things like having a StrongARM rather than ARM710 make a bigger difference)

oh well, that machine is already equipped with a SA@200Mhz , I do not want to over clock to 220Mhz , and … the 300Mhz seems to cost a lot.

ajw99uk wrote: I suggest you try comp.sys.acorn.hardware - probably a few people with unused PC cards, though I suspect mostly 486s

sure, thank you, I will also ask for a second slice-case (with pins), I am still without it and currently I do not have the CD/DVDrom because I have recycled the slot to accommodate the MC68332 board. I have recycled a CD ROM box, I have unmounted, removed the electronics, adapted the box for my MC68332 board which is perfectly fitted inside. Currently I am also trying to adapt the CDROMs front panel to an LCD, 2x20, Hitachi, backlit, plus 2 buttons that are useful for the debug interface.

In short I'd like to use the RiscPC as " (yet an other) MC68332 development station ", currently I have only the SierraC/68k under DOS, but … I can have a RiscOS C native cross-compiler to 68K (a friend has promised me), and I am already developing ethernet driver tool to directly interface the BDM, which sounds good, I mean instead of having a DOS application, under !PC, that controls the target

There are also 4 bugs with the RiscPC's RS232, and I can fix just 3 of them, but RiscOS is a funny OS, this is the main reason

ivelegacy wrote:

ajw99uk wrote: I was going to point you to this one but the auction finished earlier today

yeap, too late, there is an other auction but that dude asks too much

This one? Yes silly price (it's only 100MHz/128KB cache, CJE has 133MHz/512KB with fan for GBP60!), but you could make him an offer.
http://www.ebay.co.uk/itm/Acorn-Risc-PC ... 3f5265b67a

Your post coincided exactly with my edit to add another ebay link, currently around EUR20 plus another 10 for P&P. If that goes for a reasonable price a similarly reasonable offer on the other one would be a "market price" (in a very small market!

Agreed that the step from an SX to a 5x86 would be nice to have. I think some people has success swapping a socketed 486 on a GeminiII card for one of these, though of course you would need a GeminiII card of some kind (DX2/66, DX2/80, DX4/100; I don't think there were SX versions) to upgrade.
http://www.ebay.co.uk/itm/252051911099? ... EBIDX%3AIT
I'm a little tempted to make an offer there myself.

I wonder what happens if I replace the 486 with a Pentium1 OverDrive : will it work ?

ivelegacy wrote: I wonder what happens if I replace the 486 with a Pentium1 OverDrive : will it work ?

It might, though as far as I know the recommended "best" upgrade is a 5x86, given the 32 bit bus limitation you mentioned - see for example http://www.chiark.greenend.org.uk/~theo ... ardug.html (which starts with an SX CPU, which is what you now have?).
At the CPU level, what works on a full 486 motherboard would generally work, subject to voltage regulation and some higgles around cache configuration. But I'd worry about power requirements/heat output from a Pentium, and the Overdrive has had some pretty bad reviews. Something like the Evergreen 486->586 upgrades would be a better bet for a less DIY approach.

I exclaimed " ohhh my pants, yet an other horror story in electronics "

so I contacted the 5x86 seller on ebay/uk, and he said


I can offer -10.99GBP as discount
GBP 99,99 Buy It Now price
GBP 89,00 Special Offer price


that is … ohh cool, but CJE sells for 60GBP, including warranty
so yep, currently I still have a 4x86 Card SXL-40