Search found 515 matches

by Hippy Dave
Sun Mar 15, 2009 7:20 am
Forum: GFA BASIC
Topic: CALL and assembler why crash?
Replies: 19
Views: 3839

Re: CALL and assembler why crash?

Hi, It appears that you are loading a *.prg into an array. Two problems that can happen: 1) The program may load at an odd address 2) The program needs to be loaded with a "loader" to resolve the addresses (pc relative code will be ok), nevertheless, the code is embedded in a file that is intended t...
by Hippy Dave
Thu Mar 12, 2009 7:00 pm
Forum: Hardware
Topic: STfm prob: screen stutters "in sync" with floppy motor(!?!)
Replies: 9
Views: 2019

Re: STfm prob: screen stutters "in sync" with floppy motor(!?!)

1) Cable is getting interference. 2) PSU is getting old. 3) Capacitors drying. Q)I'm not an electronics expert really, do you mean the 2) and 3) are the same thing? A)Yes A joystick cable is not very good because the wires will get interference and crosstalk. An easy solution may be to butcher a VGA...
by Hippy Dave
Wed Mar 11, 2009 8:31 pm
Forum: Hardware
Topic: STfm prob: screen stutters "in sync" with floppy motor(!?!)
Replies: 9
Views: 2019

Re: STfm prob: screen stutters "in sync" with floppy motor(!?!)

Hi, Put a clamp-on ferrite on the outside of your cable; this may help. If you want an ideal cable, it should use individual 75-ohm coaxial cables (all the same length and twisted) for the video signals. Another possibility is that electrolytic capacitors are drying out (and losing capacitance) in y...
by Hippy Dave
Wed Mar 11, 2009 6:30 am
Forum: Hardware
Topic: 520 STFM no picture or sound from monitor port but TV OK
Replies: 19
Views: 2905

Re: 520 STFM no picture or sound from monitor port but TV OK

Diagnosis: There is nothing wrong with this computer If the rf output works fine with a tv. The problem is with the cable, monitor, or otherwise! Try the computer with a monitor and tv.
by Hippy Dave
Tue Mar 10, 2009 9:11 pm
Forum: Hardware
Topic: 520 STFM no picture or sound from monitor port but TV OK
Replies: 19
Views: 2905

Re: 520 STFM no picture or sound from monitor port but TV OK

Hi,
One possibility is that the monitor connector doesn't provide the signals. To eliminate this possibility, measure the resistance between pin10 and gnd, pin 7 and gnd, pin6 and gnd (power disconnected). The resistance should be between 100 and 200 ohms - certainly not open or shorted.
by Hippy Dave
Sat Feb 07, 2009 6:04 pm
Forum: Professionals
Topic: Any ideas on hard disk repair?
Replies: 14
Views: 1727

Re: Any ideas on hard disk repair?

After pondering over your platter swap, I'm starting to think that the voice coil magnet's
magnetic field makes it impossible to remove a platter without destroying the data.
by Hippy Dave
Fri Feb 06, 2009 1:58 am
Forum: Professionals
Topic: Any ideas on hard disk repair?
Replies: 14
Views: 1727

Re: Any ideas on hard disk repair?

Drives mark bad sectors, and also do diagnostics while powering up. The controller board is probably being pedantically uncooperative. Maybe you can find a way to trick it by running hard drive commands. (eg. if you know how it was partitioned, repartition it to something safe, then repartition it b...
by Hippy Dave
Thu Feb 05, 2009 10:50 pm
Forum: 680x0
Topic: [CODE] Fast Sqrt rout
Replies: 50
Views: 23095

Re: [CODE] Fast Sqrt rout

We can make it more accurate by making the answer $10000 for $ffff0000 and higher:
Yes, this code should be commented for those that want a 16 bit result however.
by Hippy Dave
Thu Feb 05, 2009 5:19 am
Forum: 680x0
Topic: [CODE] Fast Sqrt rout
Replies: 50
Views: 23095

Re: [CODE] Fast Sqrt rout

I also did some loop unrolling and made the msb round-up faster. I'm impressed by the add after the divu for rounding. Your method gives the same results as mine! I tried something similar (because of the success I had with rounding the first estimate) but didn't succeed here, so I rounded the resu...
by Hippy Dave
Wed Feb 04, 2009 9:17 pm
Forum: Hardware
Topic: Atari ST/STE repair help!! help!!
Replies: 3
Views: 1453

Re: Atari ST/STE repair help!! help!!

I'll hazard a guess here. So ... For the computer that failed after the floppy removal: This one is more likely to have corrupted data on the hard drive or the disk that was removed than something wrong with the hardware (a hardware problem is probably a coincidence). The other computer will have ob...
by Hippy Dave
Tue Feb 03, 2009 8:44 pm
Forum: 680x0
Topic: [CODE] Fast Sqrt rout
Replies: 50
Views: 23095

Re: [CODE] Fast Sqrt rout

I did simple testing to determine that subtracting 1 gives a better result. This Newton method Square root returns results that are always too large. This may be an artefact from using finite precision numbers. Note that subtracting 2 or more may give better results for larger roots. The second iter...
by Hippy Dave
Mon Feb 02, 2009 11:24 pm
Forum: 680x0
Topic: [CODE] Fast Sqrt rout
Replies: 50
Views: 23095

Re: [CODE] Fast Sqrt rout

Hi Guys,

I was hoping to provoke a response, and its good to see improvements already!

Dave
by Hippy Dave
Mon Feb 02, 2009 9:57 pm
Forum: 680x0
Topic: [CODE] Fast Sqrt rout
Replies: 50
Views: 23095

Re: [CODE] Fast Sqrt rout

This square root program is similar to my previous, however, it uses one less iteration while maintaining accuracy. (approx 250 clock-cycles for set-up, then 174 per iteration) The absolute worst case is less than 650 clock cycles. Note that one iteration is used for numbers less than 65536. The acc...
by Hippy Dave
Sat Jan 24, 2009 12:05 am
Forum: Hardware
Topic: Recommendations for label removal sprays
Replies: 12
Views: 2044

Re: Recommendations for label removal sprays

Many years ago I heard that pure Heptane C7H16 (septane) will remove the labels safely, and the label can be re-used.
by Hippy Dave
Fri Jan 23, 2009 12:33 am
Forum: 680x0
Topic: [CODE] Fast Sqrt rout
Replies: 50
Views: 23095

Re: [CODE] Fast Sqrt rout

Here is a Square Root for assembler speed freaks. 32 bit unsigned integer input, 16 bit unsigned integer root output. Good for rectangular to polar (magnitude conversion). - Reasonably short. (pc-relative code) - Speedy. (approx 600 to 800 clock cycles) - Exquisitely Accurate to beyond the last bit ...

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