Tatung Computer Forum

Your welcome to come and visit :) Yes, we have an Apple-1 replica that I built a couple of years ago. It works, though its actually a really limited computer due to its display using a big shift register rather than using RAM. We have quite a few 80's machines on display and working. We want to make...

Used TP to write an emulator for a Digital Equipment Corporation TU58 tape drive back in the early 90's. Its still in use now. I do remember it having the same error as the Pascal compiler on the Old PRIME mainframe I used to program on at college. As I remember, if you coded an input after a certai...

Damn, it was A10 but I was looking for failure to go high when it turned out to be a failure to go low. Setup my logic analyser on RAM address lines, RAS, WR & CAS, wrote a small bit of code to constantly write to F800 and found that when CAS became active low, A2 was high which it should not have b...

Confused So writing to address 0 changes address 0400 writing to address F800 changes address FC00 and every 400h step From the binary, changing one address changes the other 0000 = 0000 0000 0000 0000 0400 = 0000 0100 0000 0000 0C00 = 0000 1100 0000 0000 0800 = 0000 1000 0000 0000 1000 = 0001 0000 ...

Ha

if I write something to F800, FC00 changes to the same value and vice versa

F800 = 1111 1000 0000 0000
FC00 = 1111 1100 0000 0000

Looks like a problem with address A10

Of course we have an einstein on display

Now thats odd

MOS startup fills all memory with FF I believe then vectors setup from FB00 onwards. In the good machine this is so, but in the bad machine I have data in the memory map from F800 onwards which suggests I have an address decoding or ghosting RAM problem.

At least its a step forward.

So i was looking at the wrong disk ! The BBC lanuguage disk does indeed have SectorID 0 track 0 having 00 E1 00 FB 00 FA 00 FF and the rest of the sector filled with FF So, I have a machine that wont boot yet I can load into memory, the first sector of the disk with no errors. Roms swapped with no c...

Found one, but the disk is too damaged to write back the defective contents.

Hi In process of diagnosing a boot failure. The machine runs the diagnostic ROM and shows no errors but fails to boot. Now, with a known good file in a Gotek, I can boot one machine ok but the troublesome machine just hangs at the *****einstein***** logo. Thing is, from MOS if I use R 100 300 0000 0...