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by stephen_usher
Sun Sep 27, 2020 11:12 pm
Forum: HARDWARE DISCUSSIONS
Topic: TF536 + 68000 relocator and ROM board project.
Replies: 18
Views: 271

Re: TF536 + 68000 relocator and ROM board project.

I'm getting confused by the Axx notation differences between the m68k (starts at A1) and the chip (starts at A0).
by stephen_usher
Sun Sep 27, 2020 10:57 pm
Forum: HARDWARE DISCUSSIONS
Topic: TF536 + 68000 relocator and ROM board project.
Replies: 18
Views: 271

Re: TF536 + 68000 relocator and ROM board project.

Just a mo... The EPROM is only 256Kx16, so how do you fit two (potentially 256K) TOS images in there?!
by stephen_usher
Sun Sep 27, 2020 10:23 pm
Forum: HARDWARE DISCUSSIONS
Topic: TF536 + 68000 relocator and ROM board project.
Replies: 18
Views: 271

Re: TF536 + 68000 relocator and ROM board project.

Or I can use a second GAL, but that's slower.
by stephen_usher
Sun Sep 27, 2020 10:17 pm
Forum: HARDWARE DISCUSSIONS
Topic: TF536 + 68000 relocator and ROM board project.
Replies: 18
Views: 271

Re: TF536 + 68000 relocator and ROM board project.

I've just noticed a mistake. The second AND gate will not work and can be left out. Though really the /OE activation on the EEPROM should require /AS to be asserted as otherwise it could be reacting to a spurious address on the bus.

OK, I'll have to use a NOR gate in an 74LS02.
by stephen_usher
Sun Sep 27, 2020 10:14 pm
Forum: HARDWARE DISCUSSIONS
Topic: TF536 + 68000 relocator and ROM board project.
Replies: 18
Views: 271

Re: TF536 + 68000 relocator and ROM board project.

Does this logic for the ROM decode look OK? The GAL will match the address patterns for both possible ROM address ranges. I've used /AS for the ROM /CE as according to the spec. /CE should be enabled before /OE and given the logic delays this should work due to the logic delays in the GAL and 74LS08...
by stephen_usher
Sun Sep 27, 2020 6:49 pm
Forum: HARDWARE DISCUSSIONS
Topic: TF536 + 68000 relocator and ROM board project.
Replies: 18
Views: 271

Re: TF536 + 68000 relocator and ROM board project.

@exxos What model eeprom do you use for your dualtos?
by stephen_usher
Sun Sep 27, 2020 2:32 pm
Forum: HARDWARE DISCUSSIONS
Topic: TF536 + 68000 relocator and ROM board project.
Replies: 18
Views: 271

Re: TF536 + 68000 relocator and ROM board project.

OK, not strictly the project, but I decided that my dev machine needed a bit of a sprucing up, so I gave the case a good clean and then a quick, light spray job. IMG_2032.jpg Before IMG_2034.jpg During IMG_2035.jpg After OK, now the keyboard looks awful, but the retr-brightening of that will have to...
by stephen_usher
Sun Sep 27, 2020 1:11 pm
Forum: HARDWARE ISSUES
Topic: 520STFM: After replacing memory: White screen of death.
Replies: 31
Views: 298

Re: 520STFM: After replacing memory: White screen of death.

I know, I know... But the socket was a passive component... how could that possibly hurt? ;)
by stephen_usher
Sat Sep 26, 2020 11:41 pm
Forum: HARDWARE ISSUES
Topic: 520STFM: After replacing memory: White screen of death.
Replies: 31
Views: 298

Re: 520STFM: After replacing memory: White screen of death.

I rather think, there was a short under the socket... was it original "funky" socket, a modified modern one, or a modern one on the adapter board? No, I put a foam pad underneath (approximately 2mm thick) to make sure that there was no possibility that the underside of the conversion board would ge...

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