fmb@ihlpa.UUCP (03/27/87)
I have a 4.77/8 Megahertz PC clone. It is switched to 8 MHz by the CNTRL-ALT [-] keystroke. It does not have a hardware switch to toggle between 4.77/8 MHz mode, nor did it come with any SW to toggle between the 4.77/8 Mhz mode. The dealer who sold me the motherboard was absolutely no help (thats what I get for buying the cheapest turbo board I could find). My question is: Does anyone know of any software that can be used to toggle a typical "Taiwanese turbo board" between 4.77 & 8.0 Mhz? Thanks, Fernando Botelho AT&T IS Naperville, IL ...ihnp4!ihlpa!fmb
wales@ucla-cs.UUCP (03/28/87)
In article <3421@ihlpa.ATT.COM> fmb@ihlpa.ATT.COM (Botelho) writes: >My question is: Does anyone know of any software that can be used to >toggle a typical "Taiwanese turbo board" between 4.77 & 8.0 Mhz? I have a Wugo PC-II-AD, marketed by Sun Computers Inc. (not to be con- fused with Sun Microsystems, Inc., the UNIX workstation people) as a "Sun PC II". By disassembling a utility they supplied, called "TURBOPC.COM" (a TSR program which toggles the speed when I do ALT-SHIFT), I was able to figure out how to control the speed. On my system, the 04H bit of I/O port address 61H is the key: when this bit is "on", the system runs at 8 MHz, and when the bit is "off", at 4.77 MHz. Here are the programs I wrote to set "fast" and "slow" speeds. You could enter these via DEBUG (that's what I did). FASTCLK.COM SLOWCLK.COM mov dx,0061 mov dx,0061 in al,dx in al,dx or al,04 and al,0fb out dx,al out dx,al xor ah,ah xor ah,ah int 21 int 21 Note that these programs differ only in the third line. I can't guarantee, of course, that these will work for your system. If they don't, try using DEBUG on your TURBOPC.COM (or equivalent). The "u 100" command (disassemble starting at location 100H) will probably show a "jump" to some initialization code, followed by some space for holding an interrupt handler address (for chaining interrupts), followed by 40-50 bytes of interrupt handler code. This code will probably read some I/O port, reverse (toggle) the state of some bit, and write it back out. You can then write your own programs to set "high" or "low" speed. -- Rich Wales // UCLA Computer Science Department // +1 213-825-5683 3531 Boelter Hall // Los Angeles, California 90024-1600 // USA wales@CS.UCLA.EDU ...!(ucbvax,sdcrdcf,ihnp4)!ucla-cs!wales "Sir, there is a multilegged creature crawling on your shoulder."