Recent content by Dwight Elvey

Are all old MFM drives bad? When I wanted to add a hard drive to my NC4000 processor ( and I'm cheap ) I bought 3 ST506's at $5 each. I accidentally damaged one ( never rotate the spindle backwards ). Now I have 2 have these drives. I got an old XT 8 bit MFM controller ( for a few dollars ) and...

I use a EEPROM for my KIM-1 6530 replacement. It does have a write enable pin but I've no felt the need to use the hardware protection. Not only does it seem to have a robust sequence to actually program but for reasons related to the small space that I allotted to it, both the address and data...

I'm with Chuck. Not in my drives, thank you. They typically leave gobs that need to dry after using that could break lose and damage you disk or drive. You don't really know when you are done or use them two long. They are especially dangerous for many double sided drives. Get swabs with long...

I've never used one in a floppy drive. Cleaning is why swaps were created. Dwight

Its too bad it was the -002 that was bad. That one is needed to boot. The -003 code is only for I/O. It otherwise could be used for a number of Butterwoth's games. Good to see it working. Dwight

There are a couple ways. You need a florescent lamp that isn't one of the new ones. They use a high frequency and not 60 HZ, so CFL are not too good for this. I suspect an incandescent lamp with a really thin filament might work but never tried it. Something like the lamps used for sowing...

Yes, a reader but no floppy drive on the system. Anyway, a great number of interesting tapes to read. There are two ways the NIC-80 can read tapes,depending on the reader. It can do it serially with rs232 or using the parallel bus input, depending on the reader. gnupubic, you should open the...

You have a lot of floppy tapes but I see no floppy drive. I do have the drive and interface. I have one hard drive and interface. There are so many great tapes you have. WOW!. Your find is fantastic. I don't see the floppy DEMON, just a lot of applications. Be careful with the core memory...

There was one thing that you might want to include. I saw this in a printer driver code I disassemble a while back. The conditional jump instruction can be used for what I call as a SKIP instruction ( that is what I put in my disassembler ). What this is is the set the condition bits so that it...

I stand corrected. I complement both the value and the CARRY before the ADD I do not complement the CARRY when done. Extracting from my code, it is ( in Forth) Reg@ $0F XOR Carry @ 1 XOR + ACC + DUP $10 AND $10 / TO CARRY $0F AND TO ACC Dwight

If you look at the manual on bitsavers, page 30, you can see that someone made a note about the state of carry, going into the execution, that the carry was not complemented going in the operation, when showing what the operation actually did, in silicon. You are right, the carry being set is to...

On a separate subject, The Polymorphic video card has a serious timing error. I think it is funny that several others copied that error. Most displays have issues with the start of the first line ( top left ). If you have that issue it isn't something that can be easily adjusted out. It is a...

Getting the full operation of a gotek on a hard sectored disk is difficult and is not easy. There were some later soft sectored disk board from Polymorphic, for 8 inch and 5.25 inch. Still the primary drive was the hard sectored. I personally believe the hard sectored requires a track buffer...

I wonder if he pre-programmed the EEROM. For my board, there were a number of address pin swaps in order to program it from the KIM-1 as well as routing issues. ( in other words, the addresses are not 1:1 and nether are the data lines ). This would make pre-programming a little difficult as the...

I should note that Circa77 also made a regular .PLD file for the PAL. I just used the data sheet and created the file by hand. I should note that the picture on 39 had an extra wire coming off it. That was because the original PAL code had the Phase 2 clock inverted. Dwight