4000/040 running at 35 MHz (!). (by Luigi Pasciuto) 18 Jan 1996 ******************************************************************** IMPORTANT: this is a modification on A3640. HW manipulation skill is required so MAKE CARE ! TAKE CARE to electric static dis- charge, you have to be grounded before proceed !!! ******************************************************************** ******************************************************************** I'M NOT RESPONSIBLE FOR DAMAGE TO YOUR COMPUTER, THIS IS A HW MANI- PULATION, TAKE CARE !!!!!! ******************************************************************** This is a tip for everyone want to accellerate his A4000/040 spen- ding not much money. Cause of my raytracing jobs, i need more MIPS by CPU. The less expen- sive accellerator for A4000 cost $ 1000 at least (with nocpu on board). For example: Warp Engine 28 MHz costs $ 1000 with no CPU, using this tip you will spend $ 60 and will obtain same performances like Warp Engine, the difference 1000 - 60 = $940 are in your pocket! Is it suited for you ??? So I've tried to modify my A3640 CPU board to improve performances. The way is to replace the existing original oscillator on CPU board (50 MHz) with another at higher value. The value of the right frequency for your system depends on various factors: CPU frequency tolerance, CPU board quality, ecc. ecc. My experiences reports good results using 60 MHz, 65 MHz, 66.67 MHz, 70 MHz. Some people (thank you Joe !) have tried 66 MHz too with good results but I think this is an isolated one, more users reported me 66 MHz didn't work fine. What can I say ? The only way to know if it's possible to speed up your A4000/040 is to try, try and try with different oscilators (let you start with 60 MHz). I CAN'T ASSURE YOU THAT THIS TIP WORKS FINE ON EVERY A3640 BOARD !!! I THINK THAT 68040 CLOCK TOLERANCE IS THE MAJOR CAUSE OF SUCCESS OR FAIL OF THIS HACK, BUT THIS IS ONLY AN OPINION. The substituition of the oscillator on the CPU board don't cause any damage if you respect my advices. First of all, turn off your A4000, open the case and remove the CPU board A3640. Using a well grounded solder, remove the original oscil- lator and keep it. Take note of oscillator orientation on CPU board before remove it. Now, solder a 14 DIL socket on oscillator place on the board, then insert the new oscillator in the socket respecting the right orientation (have you noted it before ?). Stick a CPU cooling fan on the 68040 heat sink so that it push the air jet on the CPU. Connect the cooling fan to 12 V power supply available on spare hard disk connector. Now "cross the finger" and power on the A4000, is it booting up ??? Yes ??? WHOWWWWWW !!!!!!!! That's all !! Now you have a real 27 MIPS A4000 !!!! I'm using this tip since 1994 and it works fine without any trouble. Everyday I use my A4000 for 5/6 hours continuos with no trouble. The use of higher clock cause an increase of power consuption of CPU so it must dissipate more heat. Using the CPU cooling fan, as descri- bed before, you prevent CPU damage. However it's possible, specially in hot region and hot season, that CPU cooling is not enough. In this case you'll note a decrease in speed of system performance, the Ami- ga will slow down to stop. Dont' worry, this is a protection system developed by Motorola to prevent CPU damage. In this case power off the A4000 and wait for CPU cooling, the system will restart again. I didn't test this tip on other configurations, but i think that it must work fine the same. The AIBB 6.5 program report an average increase of performances of 35 % with a maximum of 41 %. Unfortunately this tip cause a raise of CPU/memory latency index: from 8.1 to 9.1, but you can patch this using copymemquick program, available on Aminet. 68040 at 35 MHz permits an improvement in hard disk transfer rate too, in this case you i must verify, using DiskSpeed 4.2, if there are errors with the higher speed, in this case you must modify the MAXTRANSFER parameter in HDToolBox program to 0000ffff. My hard disk (Western Digital 340 Mb, slave) transfer rate is raised from 1.3 Mb/s to 1.6 Mb/s using the MAXTRANSFER value mentioned above. In the pictures joined to this doc you can find an aid to modify your A3640 board and benchmarks obtained with AIBB 6.5. This is FREEWARE, I accept everythink as reward for it (thanks too !) If you have any trouble, contact me at the following addresses: Please mail me your Internet address, I'll include it in my mailing list so you'll receive update and news direct from me. Internet: pasciuto@settimo.italtel.it Home: PASCIUTO LUIGI VIA VERGA 10 20015 PARABIAGO (MI) ITALY Good MIPS at all ! P.S. FOR EVERYONE CAN'T FIND THE PARTS NECESSARY FOR HACKING, I CAN HELP YOU PROVIDING A COMPLETE KIT WHICH INCLUDE: 1 60 MHz OSCILATOR, 1 70 MHz OSCILATOR, 1 CPU FAN, 1 SOCKET THE COST OF THE KIT IS $ 60. FOR THE PAYMENT METHOD CONTACT ME BEFORE. PLEASE NOTE THAT THE VALUE OF THE FREQUENCY OSCI- LATORS CONTAINED IN THE KIT MAY VARIE DUE TO STORE AVAILABI- LITY. I have all the parts necessary to tip your A4000, CPU replace- ment, Motorola documetation for developing HW/SW. Do you need oscillator, fan, socket ...... ??? Call me !!!! AFFAIR !!! AFFAIR !!! I'm selling 68040 CPU tested up to 35 MHz, $ 250 (US) only !!!! Mail me if you're interested. -Luigi.